Unit 3: The Elements Ionic and Covalent Compounds Bonding (Ch 7, 8, & 9) October 3 – October 21 Science Interactive Notebook Grant Union High School 2011-2012 Science GEMS of Wisdom Writing – a way to clarify your thoughts Collaboration – a way to share your thoughts about Inquiry – a way to expand your thoughts Reading – a way to gain new knowledge to think GEMS: Scientists & Discoveries, Types of Problems to Solve, Formulas & Constants, Specialized Vocabulary, Major ideas & Facts and Discoveries, Types of Problems to Solve, Formulas & Constants, Specialized Vocabulary. Science GEMS of Wisdom Writing – a way to clarify your thoughts Collaboration – a way to share your thoughts about Inquiry – a way to expand your thoughts Reading – a way to gain new knowledge to think GEMS: Scientists & Discoveries, Types of Problems to Solve, Formulas & Constants, Specialized Vocabulary, Major ideas & Facts and Discoveries, Types of Problems to Solve, Formulas & Constants, Specialized Vocabulary Science GEMS of Wisdom Writing – a way to clarify your thoughts Collaboration – a way to share your thoughts about Inquiry – a way to expand your thoughts Reading – a way to gain new knowledge to think GEMS: Scientists & Discoveries, Types of Problems to Solve, Formulas & Constants, Specialized Vocabulary, Major ideas & Facts and Discoveries, Types of Problems to Solve, Formulas & Constants, Specialized Vocabulary Interactive Notebook Table of Contents Pg Date Left Side Items CK Pg Date Right Side Items 0 GEMS of Wisdom 1 Table of Contents 2 Score Sheet 3 Scoring Rubrics/Safety Contract 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 CK Interactive Notebook Score Sheet Unit: Quizzes/Formatives Date Name of Special Assignment Quarter Score/Max Score Name Retake Needed (yes or no) Date Scored Score/Max Peer Initial Peer Initials Parent Initial Teacher Initials Five Point Scoring Rubric 5 Points—(a WOW product) • all of the requirements are evident and EXCEEDED • the product is VERY neatly done and EXTREMELY well organized • the product shows LOTS of creativity and is colorfully illustrated • completed on time 4 Points—(What is EXPECTED) • all the requirements are evident • the product is neatly done and well organized • the product shows creativity and is colorfully illustrated • completed on time 3 Points—(Almost What is EXPECTED) • the requirements are evident (maybe 1 or 2 are missing) • the product is neatly done and organized • the product shows some creativity and is illustrated • completed on time 2 Points—(Sort of What is EXPECTED) • the requirements are evident (maybe 3 or 4 are missing) • the product is done and sort of organized • the product shows little creativity and is illustrated • completed on time 1 Points—(Two or More parts is missing) • MANY of the requirements are NOT PRESENT • The product is VERY POORLY done and POORLY organized • The product shows little TO NO creativity and THE illustrations IS POORLY DONE 0 Points—(Does not meet Standards) • Unscorable or no product I understand that I am responsible for my personal safety, as well as others in the class. I will follow the safety rules below and additional instructions given by my teacher. I understand that the following behaviors will result in a “time out” from lab, a referral, a parent conference, detention, or removal from the class: Failure to abide by class safety rules Behavior that causes injury to myself or another person Intentional damage or theft of classroom materials or equipment I will behave responsibly at all times. Understand and follow written and verbal instructions Avoid eating, drinking or chewing gum in the classroom or lab at all times Avoid any actions (horseplay, running) that might injure myself or another student Perform only authorized experiments I will work safely at all times. Wear closed toed shoes and tie my hair back in lab Understand emergency procedures Know location and use of safety equipment Wear safety goggles or other protective equipment when instructed to do so Dispose of chemicals and broken glass properly Wash hands after working with hazardous materials Report accidents or spills to the teacher immediately I will be cautious when working with laboratory equipment. Understand the proper use and care of equipment Use equipment only for its purpose as specified Treat all lab equipment – carefully I will be especially aware and cautious when dealing with heat or flames. Follow specific directions when using matches, candles, a hotplate, or burner Know the proper use of hot plates and Bunsen burners before using them Not leave hot objects unattended Keep flammable materials (alcohol, hairspray) away from flames I will be a good citizen in the classroom. Clean my work area and return supplies & equipment Dispose of all chemicals/specimens according to instructions Not touch equipment or supplies until instructed Stay out of off-limits areas Take responsibility for broken glassware, equipment, or spills Student Signature _______________________________ Parent’s Review __________________________________ California Standard Chemical Bonds 2. Biological, chemical, and physical properties of matter result from the ability of atoms to form bonds from electrostatic forces between electrons and protons and between atoms and molecules. As a basis for understanding this concept: a. Students know atoms combine to form molecules by sharing electrons to form covalent or metallic bonds or by exchanging electrons to form ionic bonds. b. Students know chemical bonds between atoms in molecules such as H2 , CH4 , NH3 , H2 CCH2 , N2 , Cl2 , and many large biological molecules are covalent bonds. c. Students know salt crystals, such as NaCl, are repeating patterns of positive and negative ions held together by electrostatic attraction between ions. d. Students know the atoms and molecules in liquids move in a random pattern relative to one another because the intermolecular forces are too weak to hold the atoms or molecules in a solid form. e. Students know how to draw Lewis dot structures. f. * Students know how to predict the shape of simple molecules and their polarity from Lewis dot structures. g. * Students know how electronegativity and ionization energy relate to bond formation. h. * Students know how to identify solids and liquids held together by van der Waals forces or hydrogen bonding and relate these forces to volatility and boiling/ melting point temperatures. Think Pair Share – What are some meanings for the term bonding __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ Metallic Ionic Covalent Bonding Introduction (215-275 textbook) Bonding occurs in order to become more stable. When a bond is formed energy is released because the resulting compound is more stable and at a lower energy state. When energy is released the term exothermic is used. Exo means______________. When bonds are broken energy is absorbed and the term endothermic is used. Endo means._________ A chemical bond results from the simultaneous attraction of electrons by two nuclei. Bonding only involves electrons. Atoms bond together to form OCTETS (eight valence electrons) the most stable state. The exceptions are hydrogen and helium which need only two electrons to fill their outer orbitals (shells) Standards Review Chemistry 2a. Students know atoms combine to form molecules by sharing electrons to form covalent or metallic bonds or by exchanging electrons to form ionic bonds depending on the atom’s electronegativity. Electronegativity - the affinity for electrons. Highest: Fluorine 4.0. A covalent bond between non-metals appears as a shared pair of electrons contained in a region of overlap between two atomic orbitals, in the localized electron model. Atoms (usually nonmetals) of similar electronegativities can form covalent bonds to become molecules. In a covalent bond, therefore, bonding electron pairs are localized in the region between the bonded atoms. In metallic bonds between metals valence electrons are not localized to individual atoms but are free to move to temporarily occupy vacant orbitals on adjacent metal atoms. For this reason metals conduct electricity well. This kind of bonding is also called the sea of electrons. Ionic bonding between metals and non-metals; occurs when an electron from an atom with low electronegativity (e.g., a metal) is removed by another atom with high electronegativity (e.g., a nonmetal), the two atoms become oppositely charged ions that attract each other. Metals tend to lose electrons and form positive ions called cations. Ions formed are smaller than the neutral atoms because they have lost electrons: Ionic radii < than atomic radii. Nonmetal tend to gain electrons and from negative ions, called anions. Ions formed are larger than the neutral atoms because anions gain electrons: Ionic radii > atomic radii. Chemical bonds between atoms can be almost entirely covalent (nonpolar), almost entirely ionic or in between these two extremes. The triple bond in nitrogen molecules (N2) is nearly 100 percent covalent as are other diatomic molecules. A salt such as sodium chloride (NaCl) has bonds that are nearly completely ionic. However, the electrons in gaseous hydrogen chloride are shared somewhat unevenly between the two atoms. This kind of bond is called polar covalent. Ionic bonds - formed between metal and nonmetal; created by a transfer of electrons; electronegativity difference > 1.7 Covalent bond - formed by the sharing of electrons between nonmetals; electronegativity difference < 1.7. Nonpolar covalent bonds have electronegativity differences <0.3 and Polar covalent bonds have electronegativity >0.3 and <1.7 Diatomic molecules are considered to have NONPOLAR covalent bonding. i.e. N2 Exception to 1.7 rule: METAL hydrides are ionic! ex. NaH Electrostatic Forces and Crystalline Structure Order the elements by increasing electronegativity Na, Rb, O, F Order the elements by decreasing electronegativity Br, I, F, Sr, Ba Electron affinity and Electronegativity Elements with a high electron affinity also have high electronegativities. One term, electron affinity, relates to attraction to gain an electron this is affinity. The other term electronegativity refers to the pull of electrons once a bond has formed. California Standard 2c. Students know salt crystals, such as NaCl, are repeating patterns of positive and negative ions held together by electrostatic attraction Description The energy that holds ionic compounds together, called lattice energy is caused by the electrostatic attraction of cations, which are positive ions, with anions, which are negative ions. To minimize their energy state, the ions form repeating patterns that reduce the distance between positive and negative ions and maximize the distance between ions of like charges. Prepare a labeled diagram to illustrate the description and how water dissolves ionic crystal lattice. Lewis Dot Diagrams and Bonding Draw the Lewis Dot Diagram below the following elements: 1. Magnesium 2. Potassium 3. Nitrogen 4. Neon 5. Aluminum 6. Sulfur 7. Lithium 8. Argon 9. Helium 10. What is an ionic bond? 11. What kinds of elements do ionic bonds form between? 12. Would Potassium (K) form an ionic bond with Fluorine (F)? Why or Why not? 13. Would Calcium (Ca) form an ionic bond with Neon (Ne)? Explain why or why not. 14. Would Nitrogen (N) form an ionic bond with Oxygen (O)? Why or Why not? 15. Would Calcium become an anion (-) or a cation (+)? Explain why. 16. Would Phosphorus (P) become an anion (-) or a cation (+)? Explain why. 2e. Students know how to draw Lewis dot structures A Lewis dot structure shows how valence electrons and covalent bonds are arranged between atoms in a molecule. Knowledge of the periodic tables allows the determination of the number of valence electrons for each element in Groups 1 through 3 and 13 through 18. Carbon, for example, would have four valence electrons. Lewis dot diagrams represent each electron as a dot or an x placed around the symbol for carbon, which is C. A covalent bond is shown as a pair of dots, or x’s, representing a pair of electrons or a line. For example, a Lewis dot diagram for methane, which is CH4, would appear as shown in Figure 3. DIRECTIONS: For each of the following, draw the electron dot structure and identify the charge (oxidation State) of the ion it will form. 1. Ba 2. O 3. Ga 4. Cl 5. He 6. P 7. Tl 8. Li 9. Al 10. K 11. Ca 12. Ar SECTION 2. Predict the chemical formulas for each of the following ionic compounds. Example: Aluminum reacts with oxygen in air to form a whitish coating. Predict the formula for the aluminum oxide formed. 13. K and O 15. Hg+2 and P 14. Al and S SECTION 3. CIRCLE THE ELEMENT IN EACH OF THE FOLLOWING IONIC COMPOUNDS WITH THE HIGHEST ELECTRONEGATIVITY. 16. MgCl2 17. AlN 18. SO4-2 SECTION 4. CIRCLE WHICH ELEMENT IN THE FOLLOWING PAIR THAT IS MOST LIKELY TO LOSE AN ELECTRON BECAUSE IT HAS A LOWER IONIZATION ENERGY. 19. As or Se 20. Kr or Ne 21. Li or F 22. H or He 23. Fr or Rb 24. B or O 25. C or Ge 26. Br or Sc 27. Be or Mg NAMING – IONIC COMPOUNDS. BINARY TWO ELEMENTS, TERNARY MORE THAN TWO ELEMENTS Compound Name Classification Chemical Formula Fe(OH)3 Pb3N4 Al2(SO4)3 Hg(OH)2 COMPOUNDS CRISS-CROSS METHOD Write the correct formula of the ionic compounds formed between the positive and negative ions. Cl K Ca Al Na Cu+1 Fe+3 NH4 O N P KCl K3P Potassium Chloride Potassium Phosphide S Write formula and name the ionic compounds formed CO3 K Ca Al Na Cu+1 Fe3+ NH4 NO3 SO4 PO4 OH Ionic Bonding Review 1. Key Idea/s: 1d. Students know how to use the periodic table to determine the number of electrons available for bonding. b. Students can determine the number of valence electrons present in a given atom based on the element’s location in the Periodic Table. How do we know how many valence electrons are in elements 2. Key Idea/s: Students can explain that only the outermost electrons [or valence electrons] are involved in bonding. What are valence electrons? 3. Key Idea/s: Students know that either positive or negative ions form and what these ions are called How does an atom become a positive ion? How does an atom become a negative ion? How do ions form neutral compounds? When do ionic compounds form How many valence electrons do elements desire? Examples: 2a has________ 3a has________ 4a has________ 5a has________ 6a has________ Which elements do not follow this trend? What kind of elements form ionic bonds? The number of valence electrons are used to determine what? 4. Key Idea/s: Ionic Radii are different from Atomic radii Explain why cations get smaller than their atomic form and anions get bigger than their atomic form 5. Key Idea/s: 2a. Students know atoms combine to form molecules by exchanging electrons to form ionic bonds. 6. Key Idea/s: 2c. Students know salt crystals, such as NaCl, are repeating patterns of positive and negative ions held together by electrostatic attraction. Discuss how dissolution breaks ionic bonds. 7. Key Idea/s: Students know the characteristics of ionic compounds What characteristics do ionic compounds share? 8. Key Idea/s Students can explain how electrical conductivity occurs How do ionic compounds conduct electricity? 9. Key Idea/s: Students can determine the bonding capacities of each atom[or element] by examining the combining ratios of the elements in the compounds it forms How many potassium ions are needed to balance the charge of one sulfide ion? 10. Key Idea/s: What are polyatomic ions? Predict the formulas for calcium chloride and potassium phosphate? Examples: 11. Key Idea 2e. Students know how to draw Lewis structures Draw KCl Draw MgCl2 12. Key idea Students know how to name ionic compounds Name MgO Na2SO4 MElizabeth/HS_Chem_Ionic_Bond_Review/2010 Standards Review Chemistry 2b. Students know chemical bonds between atoms in molecules such as H2, CH4, NH3, H2CCH2, N2, Cl2, and many large biological molecules are covalent. Organic and biological molecules consist primarily of the non-metals: carbon, oxygen, hydrogen, and nitrogen. These elements share valence electrons to form bonds so that the outer electron energy levels of each atom are filled and have electron configurations like those of the nearest noble gas element. Noble gases, or inert gases, are in the last column on the right of the periodic table and have complete outer shells filled. Non-metals forming bonds with other non-metal elements tend to form covalent bonds. Non-metals bonded together form covalently bonded molecules. For example: Nitrogen has one lone pair and three unpaired electrons and therefore can form covalent bonds with three hydrogen atoms to make four electron pairs around the nitrogen. Carbon has four unpaired electrons and combines with hydrogen, nitrogen, and oxygen to form covalent bonds sharing electron pairs. Diatomics: H2, N2, F2, O2, I2, Cl2, Br2 (Mnemonic for memorization: Have No Fear Of Ice Cold Beverages or the diatomic 7) 1. What is a covalent bond? 2. What kinds of elements does it form between? 3. Would Strontium (Sr) form a covalent bond with Chlorine (Cl)? Why or why not? 4. Would Carbon (C) form a covalent bond with Neon (Ne)? Explain why or why not. 5. Would Carbon (C) form a covalent bond with Oxygen (O)? Why or Why not? 6. Show how Chlorine would bond to Chlorine what type of bond would be formed. 7. Show how Carbon would bond to Hydrogen to form methane (CH4). How to draw Lewis structures for molecules that contain no charged atoms 1) Count the total valence electrons for the molecule: To do this, find the number of valence electrons for each atom in the molecule, and add them up. 2) Figure out how many octet electrons the molecule should have, using the octet rule: The octet rule tells us that all atoms want eight valence electrons (except for hydrogen, which wants only two), so they can be like the nearest noble gas. Use the octet rule to figure out how many electrons each atom in the molecule should have, and add them up. The only weird element is boron - it wants six electrons. 3) Subtract the valence electrons from octet electrons: Or, in other words, subtract the number you found in #1 above from the number you found in #2 above. The answer you get will be equal to the number of bonding electrons in the molecule. 4) Divide the number of bonding electrons by two: Remember, because every bond has two electrons, the number of bonds in the molecule will be equal to the number of bonding electrons divided by two. 5) Draw an arrangement of the atoms for the molecule that contains the number of bonds you found in #4 above: Some handy rules to remember are these: o Hydrogen and the halogens bond once. o The family nitrogen is in bonds three times. So does o The family oxygen is in bonds twice. boron. o The family carbon is in bonds four times. A good thing to do is to bond all the atoms together by single bonds, and then add the multiple bonds until the rules above are followed. 6) Find the number of lone pair (nonbonding) electrons by subtracting the bonding electrons (#3 above) from the valence electrons (#1 above). Arrange these around the atoms until all of them satisfy the octet rule: Remember, ALL elements EXCEPT hydrogen want eight electrons around them, total. Hydrogen only wants two electrons. Other methods can be used: 1) take total number of valence electrons and divide by 2 to find how many unshared and shared pairs, and then arrange. Practice Naming Covalent Compounds Prefix Number 1. Name the following molecules. 1 SF6 2 3 C4H10 4 5 CCl4 6 7 BH3 8 9 H2 10 2. Write the following formulas from the names. Carbon tetrabromide Heptanitrogen nonasilicide Antimony pentasulfide Disulfur decafluoride In your own words, write the steps you would take to draw dot structures for molecules. Then draw the following: __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ H2S CCl2Br2 O3 N2 H2O2 O2 Covalent Compounds Worksheet 1) 2) 3) 4) Based on the properties of the following materials, determine whether they are made of primarily ionic compounds or covalent compounds: a) telephone receiver: ______________________________________ b) concrete: ______________________________________________ c) gasoline: ______________________________________________ d) candy corn: ____________________________________________ Name the following covalent compounds: a) SiF4 __________________________________________________ b) N2S3 _________________________________________________ c) HBr __________________________________________________ d) Br2 __________________________________________________ Write the formulas for the following covalent compounds: a) diboron hexahydride ____________________________________ b) nitrogen tribromide ______________________________________ c) sulfur hexachloride ______________________________________ d) diphosphorus pentoxide __________________________________ Write the empirical formulas for the following compounds: To find the empirical formula divide by the smallest subscript number. This becomes the mole ratio of the elements and is represented by subscripts in the empirical formula. a) C2H4O2 _______________________________________________ b) boron trichloride ________________________________________ c) methane ______________________________________________ d) C6H12O6 ______________________________________________ 5) List three differences between ionic and covalent compounds: 6) Explain why ionic compounds are formed when a metal bonds with a nonmetal but covalent compounds are formed when two nonmetals bond. Positive ion Negative ion Formula Formula Mass Molar Mass 1. Sodium Iodide Na+ I- NaI 22.99+126.9=149.89 g 2. Silver( I ) sulfide Ag+ S2- Ag2S Name of Ionic Compound 3. Barium sulfate 4. Lithium sulfide 5. Sodium hydroxide 6. Zinc sulfate Zn2+ 7. Iron(III) phosphate Fe3+ 8. Nickel (II) hydroxide Ni2+ 9. Cr3+ Chromium (III) oxide 10. Iron (III) sulfate 11. Copper (II) nitrate 12. Copper (II) carbonate 13. Magnesium phosphide 14. Aluminum nitrate Compare and Contrast Covalent and Ionic Bonds 1. Define the following: a. Electronegativity b. Ionization Energy c. Electron d. Covalent Bond e. Ionic Bond f. Valence Shell g. Lone Pair h. Bonding Pair i. Nonmetal j. Metal 2. Using 9 of the 10 definitions you just wrote, compare and contrast covalent and ionic bonds. __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ Worksheet: Introduction to Bonding1 For each of the following statements, write ionic, covalent or metallic bonds. ______________ electrons are shared ______________ electrons delocalized ______________ electrons are transferred ______________ crystal lattice ______________ luster ______________ nonconductors in the solid, molten, and dissolved state ______________ malleable and ductile ______________ high melting and boiling points ______________ volatile liquids and gases ______________ weaker forces between atoms ______________ hard—difficult to crush What is the difference between a cation and an anion? In a polar covalent bond, the electrons are shared ____________. In a nonpolar covalent bond, the electrons are shared ____________. Predict what type of bond will form between the following pairs of atoms by stating element type (metal, metalloid, nonmetal) F and F Na and O Cl and Cl Ti and O Fe and Fe Mg and O O and H Ca and S Ag and Ag 5.5 Modified 10/5/11 by MElizabeth Be and Cl 1 CHEMISTRY: A Study of Matter, © 2004, GPB, Note Taking Guide: Episode 5012 A chemical bond - forms when 2 or more atoms rearrange ____________ _____________ to increase ________________. ionic bond - forms when valence _____________ are _____________ from one atom to another forming salts. Ionic bonds usually form between metal and nonmetal elements. cation – atom __________ electrons to become ______ charged anion - atom __________ electrons to become ______ charged In ionic compounds the ions are arranged in a ___________ ___________. __________ forces hold the ions together (these are electrostatic forces). Properties of ionic compounds: high ____________ and ___________ points ___________ - not easily ______________ _____________ electricity when ___________ or______________ because the ions are free to __________. Does not conduct electricity when a solid Covalent bond - ______________ are _____________, forming _______________ held together by covalent bonds. Occurs usually with non-metal elements. Covalent compounds have ____________ forces holding the _____________ together. Properties of covalent compounds: • lower ____________ and ___________ points • Many covalent compounds are _____________ liquids or gases. • ____________– easier to ___________ • are not ________________ of electricity Compound Solid Conductivity Dissolved in Water Conductivity Bond Type Table Salt (NaCl) Para dichloro benzene Copper Sulfate (CuSO4) Ethanol (C2H2OH) Sugar (sucrose) Selzer (NaHCO3) Electronegativity - property that tells how strong an atom’s ____________ is for an _____________. Since oxygen has a ______________ electronegativity than hydrogen, oxygen holds onto shared electrons ____________, giving the oxygen a __________ negative charge and the hydrogen a partial _____________ charge. 2 CHEMISTRY: A Study of Matter© 2004, GPB, 5.1 polar covalent bonds: • electrons are shared _________________, creating partially charged ends or _______. nonpolar covalent bonds: • electrons are shared ________________ because atoms have the same electronegativities Electonegativity difference: Greater than or equal to 1.7 Between 1.7 and 0.3 Less than or equal to 0.3 Examples: Type of Bond Mg and F? S and O? Program 501, problem set 1: What type of bond will form between . . . Li and Cl? C and O? Na and Cl? Cl and Br? S and H? Al and Al metallic bond – occurs between metal elements; electrons are ________________ (creates a “____ of ___________”) properties of metals: 1. _______________________________________________________________ 2._______________________________________________________________ 3._______________________________________________________________ 4._______________________________________________________________ Summary ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________ ___________________________________________________________ The Chemistry Quiz CR1._____ CR2._____ 1._____ 2._____ 3._____ 4._____ 5._____ Identify the type of element whether metal, metalloid, and non-metal and whether it will form a cation, anion, or if an ionic form is usually not present and draw its atomic Lewis dot structure. O non-metal, forms an anion (O-2) N H F Xe Ca S Mg Identify the type of elements that form the following bond types Ionic_______________________________________________ Covalent ____________________________________________ Metallic_____________________________________________ Identify the type of covalent or ionic bond present between the following elements and draw their Lewis Dot Structures 1. O2 2. NH3 3. F2 4. N2 5. H2O 6. Cl2 7. CaCl2 2d. Students know the atoms and molecules in liquids move in a random pattern relative to one another because the intermolecular forces are too weak to hold the atoms or molecules in a solid form The term intramolecular force refers to bonding between atoms in compounds: ionic, covalent, and metallic bonds The term intermolecular forces refers to attractions between compounds such as dipole-dipole (water), hydrogen bonds which are easily broken and formed. In any substance at any temperature, the forces holding the material together are opposed by the internal energy of particle motion, which tends to break the substance apart. In Notice how both the particles in a solid and liquid are close together. If the liquid and solid states are so similar to each other on the molecular scale because they experience intermolecular forces, in what way do they differ? The main point of difference is the relative movement of molecules in relation to neighboring molecules. In a solid, each molecule can vibrate and rotate in place, but cannot change places or move past other molecules. That is, they can wiggle around, but they can’t go anywhere. In a liquid, by contrast, molecules stay close to each other but they readily move past each other. A human analogy is helpful here3. Imagine that each student on your campus is a molecule. When you are sitting in a classroom, you and the other students are collectively acting as a solid. You can move about in your seat, turn around and the like. But, you do not readily change seats with other students during the class period. The students are solid. Now imagine a crowded, really crowded, dance floor. You are just as close to your neighbors as you were in lecture, if not closer, but now you are free to move about and change who you are near. The gaseous state is represented by the students moving about between classes. Each goes his or her own way, briefly interacting but mainly moving independently of one another. When enough energy is added to the solid, the kinetic energy of the atoms and molecules increases sufficiently to overcome the attractive forces between the particles, and they break free of their fixed lattice positions. This change, called melting, forms a liquid, which is disordered and non-rigid. The particles in the liquid are free to move about randomly although they remain in contact with each other. The particles in a gas are free to move about randomly INTERMOLECULAR FORCES _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ 3 http://employees.oneonta.edu/viningwj/Chem112/Chapter%2011_Forces_Between_Molecules_and_the_Liquid_State_1_9.pdf Naming Mixed Ionic and Covalent Compounds Name the following compounds. Remember, they may be either ionic or covalent compounds, so make sure you use the right naming method! 1) NaF __________________________________________ 2) NF3 __________________________________________ 3) Li2O __________________________________________ 4) Al2S3 __________________________________________ 5) MgSO4 __________________________________________ 6) SiH4 __________________________________________ 7) KNO3 __________________________________________ 8) P2O5 __________________________________________ 9) CH4 __________________________________________ 10) Ca(OH)2 __________________________________________ Write the formulas for the following compounds. Remember, they may be either ionic or covalent compounds, so make sure you use the right method! 11) lithium chloride __________________________________________ 12) nitrogen trichloride __________________________________________ 13) sodium oxide __________________________________________ 14) dinitrogen trioxide __________________________________________ 15) ammonia __________________________________________ 16) diboron dihydride __________________________________________ 17) potassium phosphide _________________________________________ 18) oxygen difluoride __________________________________________ 19) magnesium nitrate __________________________________________ 20) aluminum carbonate __________________________________________ What type of elements give off valence electrons to achieve a configuration of a noble gas? How is a covalent bond formed? Write the Lewis structure for NH3 What type of elements receive valence electrons to achieve a configuration of a noble gas? How is an ionic bond formed? Write the Lewis structure for CO2 Which group of metals is the most chemically active? Write the Lewis structure for F2 Write the Lewis structure for C2H4 Which group of nonmetals is the most chemically active? Write the Lewis structure for O2 The composition of a compound contains only C, O, and H atoms. What type of bond does the compound have? According to the periodic table, which two elements in each set of elements will likely form an ionic bond? Write the Lewis structure for H2O Given the chemical formula of a compound, how will you tell whether the compound is an ionic compound or molecular compound? Of the seven diatomic molecules, which ones contains A double bond? Write the Lewis structure for N2 A 1 14 17 18 B 2 3 17 18 Elements in the same group have similar physical and chemical properties because they have the same number of _____________? What type of elements have atoms arranged in crystal structure? Solid, liquid or gas? A triple bond? Which groups on the periodic table would form ions with the following charges: a) 1+ c. 2+ b) 1- d. 2- Show how you determine the mass of one mole of CO2 In the periodic table, what group of elements has the most stable valence electron configuration in the ground state? Using the electronegativity Show how you determine the values on p 263, how would mass of one mole of you know if the bond between Mg (C2H3O2)2 two atoms is ionic? In a binary ionic compound, one of the elements is Cl. Which of the following would the other element most likely to be? Given different pairs of atoms, how would you decide which has the most polar bond? Show how you determine the mass of one mole of Fe(NO3)3 The Lewis structure of an atom has eight dots. Name the elements with the same Lewis structure. Given several bars of different metals each containing one mole. Identify the metals with the following approximate masses. Cl I Mg Br What are the seven diatomic molecules? a) 27 g b) 65 g c) 59 g d) 40 g Which part of the periodic table are these located? Which one has a larger ion than its neutral atom? metals __________ a. Ca b. F nonmetals _________ c. Zn d. Cs metalloids _________ What type(s) of elements would make a. ionic bond b. covalent bond CHEMICAL BONDING AND ATOMIC STRUCTURE VIDEO NOTES Learning Objectives Visualize chemical bonds as electrostatic forces between atoms Compare behavior of valence electrons in metallic and covalent bondings Recognize that the making and breaking of bonds involves energy changes Compare the structure of atomic, ionic, and molecular crystals Use types of bonding to account for physical and chemical properties Appreciate the importance of the bonding capacity of carbon Use electronegativity to account for trends in bonding in the periodic table Before Viewing 1. What are the laws of electrostatics as applied to charged bodies. 2. What are valence electrons? After Viewing 1. Explain why a football field was used to describe the relative size of an atom? 2. What are the three kinds of bonds? 3. What common properties of Fe and Cu can be explained by the metallic bond? 4. How can you account for differences in the conductivity of iron and copper? 5. What kind of bond would you expect between atoms of two different metals? Explain 6. What kind of bond would you expect between two different non-metals? Explain 7. Explain how the bonds transmit electricity and heat differently. 8. What does molten mean? 9. What does sublimation mean (it happens to iodine crystals) 10. In what ways can atoms of elements achieve the configuration of noble gases? 11. Use atomic structures to account for the increase in electronegativity across a period; its decrease from the top to bottom of a group. The Alkaline Earth Elements Background Information The arrangement of the elements in the periodic table is one of the most important achievements in modern chemistry. The physical and chemical properties of elements change in a regular pattern as you go both across the rows and down the columns of the periodic table. As a result, when elements close to each other in a row or column are compared, they have many of the same properties. However, when elements farther away from each other in a row or column are compared, they have more dissimilar properties. The elements in Group 2 of the periodic table are known as the alkaline earth elements. Like all members of a group, or family, of elements, they have certain properties that change in a regular pattern within the group. One of these properties is the ability to form a precipitate, or solid substance, as a result of a chemical reaction. The precipitate cannot dissolve in water and eventually settles to the bottom of the container. In this investigation, you will compare the abilities of the alkaline earth elements to form precipitates as a result of a chemical reaction. Question: Will the ability of the alkaline earth elements to form precipitates increase or decrease as you move from top to bottom? Hypothesis: Materials (per group) Safety goggles Spot plate Sheet of notebook paper Procedure 1. Place the spot plate in the center of a sheet of notebook paper so that there are 4 spots running down and 3 spots running across. See Figure 1. 2. Along the side of the notebook paper next to each of the four spots, write the names of the four alkaline earth elements that are present in each nitrate compound listed in the materials you are using. Write them in the same order in which they are listed. See Figure 1. 3. Along the top of the notebook paper next to each of the three spots, write the names of the three substances that are combined with potassium in the materials you are using. See Figure 1. Dropper bottles of: magnesium nitrate calcium nitrate strontium nitrate barium nitrate potassium carbonate potassium sulfate potassium chromate 4. Put on your safety goggles. Place 3 drops of potassium carbonate in each of the four spots under the word "carbonate." Place 3 drops of potassium sulfate in each of the four spots under the word "sulfate." Place potassium chromate in each of the four spots under the word "chromate." Be very careful not to mix the liquid from one spot with the liquid from another. 5. "Shake the dropper bottle of magnesium nitrate and place 3 drops in each of the three spots in the row labeled "magnesium." Observe each spot carefully and record the result in the Data Table. Repeat this procedure using the dropper bottles containing calcium nitrate, strontium nitrate, and barium nitrate. Be very careful not to mix the liquid from one spot with the liquid from another. 6. After recording your results, wash your spot plate thoroughly with soapy water and a brush. Observations DATA TABLE (2 points) (Use ppt for a precipitate and NR for no reaction.) Alkaline earth Metal Carbonate Sulfate Chromate Magnesium Calcium Strontium Barium Conclusion: (8 points) (In the form of a paragraph.) 1. Restate your hypothesis. 2. Was your hypothesis supported or denied? Explain. 3. Was there evidence of a chemical reaction occurring in any of the spots? Explain your answer. 4. Which alkaline earth element formed the smallest number of precipitates? 5. Which alkaline earth element formed the greatest number of precipitates? 6. What is the relationship between the number of precipitates formed and the location of the alkaline earth element on the periodic table? 7. If the ability of an alkaline earth element to form a precipitate is an indication of its ability to chemically react with other substances, which is the most reactive element? The least reactive? 8. List the alkaline earth metals in order of their chemical reactivity, starting with the most reactive. 9. How does the order of the elements you listed in question 8 compare to their order in the periodic table? Application and Critical Thinking (4 points) (Answer question below.) 1. Group 1 in the periodic table is known as the alkali metals. Based on your investigation of' the Group 2 elements, predict the comparative reactivity of the elements in Group 1 of the periodic table. 2. If you had a solution containing a mixture of magnesium, strontium, and barium, how could you separate the three elements (Hint: Review the information in the Data Table.) Vocabulary and Basic Concepts and Properties Fill in the following blanks using the work bank. Metallic Neutral Nucleus Protons Affinity Charge Conductivity Covalent Crystal lattice Force Ionic Ionization Malleability substances Lowest 1. A chemical bond in an attractive _______________________ that holds atoms together. 2. Chemical bonding is the process of atoms combining to form new __________________________. 3. Matter tends to exist in its ______________________________ energy state. 4. A(n) __________________________ bond is a bond in which one atom donates electrons to another atom. 5. When the number of protons equals the number of electrons an atom has a _________________________ charge. 6. Ions are atoms with a positive or negative _______________________________. 7. _______________________________ is the process of removing electrons from atoms to form ions. 8. Electron_________________________________ is the tendency of an atom to gain electrons when forming bonds. Challenge: What is the term for an atom’s tendency to take electrons:_________________________ 9. A bond in which atoms share electrons is called a _________________________ bond. 10. In a(n) ____________________________ bond many electrons are share by many atoms. 11. Metallic bonds are ____________________________________ thus metals are able to be pounded into many shapes. 12. Ionic compounds have a low _____________________________ in the solid state, and a higher _________________________(same work) in the molten state. Indicate whether the following statements are true (T) or false (F). If the statement is false, re-write the statement to make it true. 1. Chemical bonding is the process of atoms combining to form new substances. 2. Valence electrons are in the innermost energy level. 3. Matter in its lowest energy state tends to be more stable. 4. Particles with a positive or negative charge are called ions. 5. One property common to metals is ductibility. 6. Covalent molecules tend to have higher melting and boiling points compared to ionic compounds. 7. Covalent molecules conduct electricity in all states. 8. Hydrogen bonding intermolecular forces are stronger than London Dispersion intermolecular forces. 9. Ionic compounds typically exist in the gaseous phase at room temperature. 10. When an atom loses on or more electrons it becomes negatively charged and we call it a cation. 11. Polar molecules have a permanent dipole moment. 1. Chemical compounds are formed when atoms are bonded together Breaking a chemical bond is an endothermic process. Forming a chemical bond is an exothermic process. Compounds have less potential energy than the individual atoms they are formed from. 2. Two major categories of compounds are ionic and molecular (covalent) compounds. 3. Compounds can be differentiated by their chemical and physical properties. Ionic substances have high melting and boiling points, form crystals, dissolve in water (dissociation), and conduct electricity in solution and as a liquid. Covalent or molecular substances have lower melting and boiling points, do not conduct electricity. Polar substances are dissolved only by another polar substance. Non-polar substances are dissolved only by other nonpolar substances. 4. Chemical bonds are formed when valence electrons are: Transferred from one atom to another – ionic. Shared between atoms – covalent. Mobile in a free moving “sea” of electrons – metallic. 5. In multiple (double or triple) covalent bonds more than 1 pair of electrons are shared between two atoms. 6. Polarity of a molecule can be determined by its shape and the distribution of the charge. Polar molecules must have polar covalent bonds. Polar molecules are asymmetrical. Nonpolar molecules are symmetrical and/or have no polar covalent bonds. 7. When an atom gains an electron, it becomes a negative ion, anion, and its radius increases. 8. When an atom loses an electron, it becomes a positive ion, cation, and its radius decreases. 9. Atoms gain a stable electron configuration by bonding with other atoms. Atoms are stable when they have a full valence level. Most atoms need 8 electrons to fill their valence level. H and He only need 2 electrons to fill their valence level. The noble gasses (group 18) have filled valence levels. They do not normally bond with other atoms. 10. Electron-dot diagrams (Lewis structures) represent the valence electrons in elements, compounds and ions. Electrons in Lewis structures are arranged by their orbitals. The first two electrons are placed together in the “s” orbital. The remaining electrons are spread among the 3 “p” orbitals. The “s” orbital must be filled first. Then each “p” orbital must have one electron before another “p” orbital gains a second. The filling of electrons in a dot diagram is accomplished by putting one dot on each of four sides before doubling up. 11. Electronegativity indicates how strongly an atom of an element attracts electrons in a chemical bond. These values are based on an arbitrary scale. Electronegativity can also be described as electroaffinity. 12. The electronegativity difference between two bonded atoms can determine the type of bond and its polarity. 0.0 - 0.4 = non-polar covalent 0.4-1.7 = polar covalent 1.7+ = ionic 13. Bonding guidelines: Metals react with nonmetals to form ionic compounds (salts). Nonmetals bond with nonmetals to form covalent compounds (molecules). Ionic compounds with polyatomic ions have both ionic and covalent bonds. 14. Intermolecular forces allow different particles to be attracted to each other to form solids and liquids. Hydrogen bonds are an example of a strong IMF between atoms. Hydrogen bonds exist between atoms of hydrogen and oxygen, fluorine, or nitrogen. Substances with hydrogen bonds tend to have much higher melting and boiling points than those without hydrogen bonds. 15. Physical properties of a substance can be explained in terms of chemical bonds and intermolecular forces. These include conductivity, malleability, solubility, ductility, hardness, melting point and boiling point. Unit 3 Bonding Study Guide Chemistry Standard Set 2 Key Vocabulary Terms 1. 2. 3. 4. 5. 6. 7. 8. Ionic Bond Covalent Bond Metallic Bond Oxidation State Coefficient Subscript Superscript Metal 9. Non-metal 10. Neutrality 11. Electrostatic Attraction 12. Cation 13. Anion 14. Shared Pairs 15. Unshared Pairs 16. Outer Electrons/Valence Electron Concepts 1. 2. 3. 4. Orbitals – Filled – octet rule. Energy – energy to form bonds, bond energy Crystal Lattice – Alternating positive and negative ions to form ionic solids Properties of Covalent, Ionic, and Metallic Compounds Covalent – non-metals, lower melting points, non-conductor of electricity Ionic – metal and non-metals, higher melting points, conductor of electricity Metallic – metals, conductor of electricity and heat, malleability, ductility, reacts with acid 5. Neutrality in atoms and in the formation of formulas (sum of positive charge = sum of negative charge) 6. Nomenclature- primarily ionic (nonmetal ending –ide) and some covalent (e.g., mono, di , and tri) 7. Formation and Dissolving Items for Memorization Polyatomic Ions Nitrate ion Sulfate ion Ammonium ion Phosphate ion Hydroxide ion Carbonate ion NO3-1 SO4-2 NH4+1 PO4-3 OH-1 CO3-2 Diatomic Molecules Hydrogen H2 Nitrogen N2 Chlorine Cl2 Iodine I2 Bromine Br2 Fluorine F2 Oxygen O2 Transition Metal Oxidation States Iron Fe II and III Copper Cu I and II Zinc Zn II Gold Au I and III Mercury Hg I and II Lead Pb II and IV Skills 1. Ability to draw Lewis Dot Structures Atoms (e.g., Na, Ba, Al, C, N, O, Cl, and Ne) Covalent Compound (e.g., N2, O2, Cl2, and H2) Polyatomic Structure (e.g., H2O, CO2, and CH4) 2. Ability to inventory compounds: Number and Type of Atoms (e.g., Al2(CO3)3, ( NH4)3PO4, and Ba(OH)2) 3. Ability to name ionic compounds given the formula and write the formula given a name (e.g., magnesium bromide, calcium hydroxide, iron III sulfate, and gold I phosphate) 4. Ability to predict bond types (i.e., ionic, covalent, and metallic) Atomic Structure Review Worksheet 1. The 3 particles and respective charges of the atom are: a. ______________________ b. ______________________ c. ______________________ 2. The number of protons in one atom of an element determines the atom’s_______________________ , and the number of electrons determines ______________________ of and element. 3. The atomic number tells you the number of ______________________ in one atom of an element. It also tells you the number of ______________________ in a neutral atom of that element. The atomic number gives the “identity “ of an element as well as its location on the Periodic Table. No two different elements will have the ______________________ atomic number. 4. The _________________________________ of an element is the average mass of an element’s naturally occurring atom, or isotopes, taking into account the ______________________ of each isotope. 5. The ____________________________________ of an element is the total number of protons and neutrons in the ______________________ of the atom. 6. The mass number is used to calculate the number of ______________________ in one atom of an element. In order to calculate the number of neutrons you must subtract the ______________________ from the ______________________ . 7. Give the symbol and number of protons in one atom of: Lithium __________________ Bromine __________________Iron ______________________ Copper __________________ Oxygen __________________ Mercury __________________Krypton __________________ Helium __________________ 8. Give the symbol and number of electrons in a neutral atom of: Uranium __________________ Chlorine __________________Boron __________________ Iodine __________________ Antimony __________________ Xenin __________________ 9. Give the symbol and number of neutrons of the most common isotope in one atom of: (To get “mass number”, you must round the “atomic mass” to the nearest whole number) Show your calculations. Barium __________________ Bismuth __________________ Carbon __________________ Hydrogen __________________ Fluorine __________________ Magnesium __________________ 10. Name the element which has the following numbers of particles: a. 26 electrons, 29 neutrons, 26 protons _____________________ b. 53 protons, 74 neutrons _____________________ c. 2 electrons (neutral atoms) _____________________ d. 20 protons _____________________ e. 86 electrons, 125 neutrons, 82 protons (charged atom) _____________________ f. 0 neutrons _____________________ 11. If you know only the following information can you always determine what the element is? (Yes/No). a. number of protons ___________ b. number of neutrons___________ c. number of electrons in a neutral atom___________ d. number of electrons___________ PRACTICE TEST 1. During a flame test, ions of a specific metal are heated in the flame of a gas burner. A characteristic color of light is emitted by these ions in the flame when the electrons a) gain energy as they return to lower energy levels b) gain energy as they move to higher energy levels c) emit energy as they return to lower energy levels d) emit energy as they move to higher energy Levels 2. The high electrical conductivity of metals is primarily due to a) high ionization energies b) filled energy levels c) mobile electrons d) high electronegativity’s 3. Which statement best describes the density of an atom’s nucleus? a) The nucleus occupies most of the atom’s volume but contains little of its mass. b) The nucleus occupies very little of the atom’s volume and contains little of its mass. c) The nucleus occupies most of the atom’s volume and contains most of its mass. d) The nucleus occupies very little of the atom’s volume but contains most of its mass. 4. Which Group of the Periodic Table contains atoms with a stable outer electron configuration? a) 1 b) 16 c) 8 d) 18 5. An atom of carbon-12 and an atom of carbon-14 differ in a) atomic number b) mass number c) nuclear charge d) number of electrons 6. Which list of elements contains two metalloids? a) Si, Ge, Po, Pb b) Si, P, S, Cl c) As, Bi, Br, Kr d) Po, Al, I, Xe 7. Which is the negatively charged particle located outside the nucleus of an atom? (1) electron (2) neutron (3) silicon (4) Which of the atoms pictured is not likely to form an ion? (1) C (2) Na (3) O (4) they are all equally likely to form an ion proton 8. Which of the atoms pictured is likely to form an anion? (1) C (2) Na (3) O (4) they are all equally likely to form an ion 9. In the periodic table of the elements, elements in Group 1 have how many outer electrons? (1) 0 (2) 1 (3) 4 (4) 8 10. Which type of nuclear radiation (beta particles, gamma rays, or alpha particles) can be blocked by…? a) a piece of paper b) a block of wood c) a piece of lead _____________ ___________ ____________ 11. Elements from which two groups in the periodic table would most likely combine with each other to form an ionic compound? A. 1 and 2 B. 1 and 17 C. 16 and 17 D. 17 and 18 12. The diagram below shows the structure of a brain chemical called acetylcholine: Based on the nature of the elements making up acetylcholine, the bonds present in the compound are most likely… A. nuclear C. hydrogen B. metallic D. covalent 13. Which of the following elements can form an anion that contains 54 electrons, 74 neutrons, and 53 protons? The illustration below shows two atoms of a fictitious element (M) forming a diatomic molecule. 14. What type of bonding occurs between these two atoms? A. covalent B. ionic C. nuclear D. polar 15. When elements from group 1 (1A) combine with elements from group 17 (7A), they produce compounds. Which of the following the correct combining ratio is between group 1 (1A) elements and group 17 (7A) elements? A. 1:1 B. 1:2 C. 2:1 D. 3:2 16. The bonds in BaO are best described asA. covalent, because valence electrons are shared B. covalent, because valence electrons are transferred C. ionic, because valence electrons are shared D. ionic, because valence electrons are transferred 17. The strength of an atom’s attraction for the electrons in a chemical bond is the atom’sA. electronegativity C. heat of reaction B. ionization energy D. heat of formation 18. The chemical bond between which two atoms is most polar? A. C–N B. H–H C. S–Cl D. Si–O 19. When cations and anions join, they form what kind of chemical bond? A. ionic B. hydrogen C. metallic D. covalent 20. Which of the following atoms has six valence electrons? A. magnesium (Mg) B. silicon (Si) C. sulfur (S) D. argon (Ar) 21. Which change in state would involve a decrease in the intermolecular force of attraction holding the water particles together? A. H2O(l) → H2O(s) B. H2O(g) → H2O(l) C. H2O(g) → H2O(s) D. H2O(s) → H2O(l)