PUTTING ATOMS TOGETHER Chapter 7 TERMINOLOGY Molecule – two or more atoms of the same or different elements that are chemically joined together in a unit. nitrogen 20% • Ex. Air = roughly 80% _______________ molecules, _____ oxygen molecules, and trace amounts of H2O and CO2 TERMINOLOGY notation that indicates the type and number Chemical Formula – of atoms in a pure substance above/after in chemistry •Superscript - small numbers written ____________, usually indicates a charge Mg2+ below/after tells us how many • Subscript – small number ___________, atoms there are O2 = 2 oxygen atoms Diatomic Elements – Elements that exist as molecular elements consisting of 2 atoms. *7 DIATOMIC MOLECULES These seven elements occur naturally as molecules containing two atoms. “HONClBrIF” • What element is this? • How many valence electrons does it start off with? • How many does it end up with once it forms a bond? MOLECULAR COMPOUNDS Sharing is caring! What do we call rxn’s that release energy/heat? What do we call rxn’s that require it? TERMINOLOGY Molecular Compounds – Compound consisting of two or more different elements with neutral charges that are bonded together. non-metal • Involves two _______________ (includes hydrogen) elements joining together and sharing valence electrons to fill their ________ energy level their outer __________________ (shell). A simulation of the reaction: 2H2 + O2 2H2O Means electrons “LEAN” or migrate towards one molecule creating partial + and - charges Forces that hold atoms together Represent “potential” energy Illustration to the right hydrogen shows two __________ molecules and a single oxygen _______ molecule. Hydrogen wants to have a full valence ________ shell (first shell 2 can hold a max. of __) meanwhile the oxygen atom also wants to have a full valence shell (2nd shell 8 Therefore a can hold __). sharing of electrons ____________________ occurs. 2H + 1O H2O A key aspect of molecular compounds is the fact they are dependent____ on arrangement ______________________ ____________________. Only certain combinations in __________ are found in nature. fixed _______________________ amounts Ex. O2 = Oxygen Gas, meanwhile O3 = Ozone •The above example highlights the fact that a change in configuration ______________________________________ dramatically changes the compound and how it affects us. ______________________________________________ These molecules can be drawn as Bohr-Rutherford __________________________________________ diagrams or as Lewis dot diagrams ____________________________________ with the shared pair of electrons represented by a _____, 2 pairs by a ______, or 3 sets of shared electrons by _____. The most that will ever be shared is 3. IONIC COMPOUNDS TERMINOLOGY • Def. Ionic Compound: Compound consisting of a positively charged (cation) and negatively charged (anion) ion. metal • Involves a ___________ + a _____________ joining non-metal giving away together, with the metal _____________ its ___________ _________ valence electrons and the __________ non-metal taking them. IONS a particle that has a + or - charge • Def. Ion –_________________________________ 2 forms Cation = Positive 1. _________ Anion = Negative 2. _________ WHY DOES THE METAL ALWAYS GIVE AWAY ITS VALENCE ELECTRONS AND THE NON-METAL ALWAYS TAKE THEM? • Think about this silently (use your notes or textbook as a reference) ANSWER • It is easier for a metal to give up 1 to 4 electrons than try to take enough to fill its valence shell. • For non-metals, they generally only need 1 or 2 extra’s to fill their shells, so it is easier for them to take 2 than give up 6. • Based on strength of nuclear charge • When an atom gains an electron, it becomes negatively charged (more electrons than protons ). anion • This is called an ________ • In the same way that non-metal atoms can gain electrons, metal atoms can lose electrons. • They become positively charged cations ________. IONS Here is a simple way to remember which is the anion and which the cation: This is Ann Ion. Two N’s in ANION for Negative This is a cat-ion. A “T” in CATION for Positive She’s unhappy and negative. He’s a “plussy” cat! IONIC RADIUS • Cations are always smaller than the original atom. • The entire valence shell is removed during ionization. • Conversely, anions are always larger than the original atom. • Electrons are added to the valence shell to fill it up (stabilize it). # of + Charge (Protons) # of - Charge (Electron) Overall Ionic charge Sodium Sodium Chlorine Chlorine Atom, Na Ion, Na+ Ion, Cl- Atom, Cl IONS • Based on the way the periodic table is arranged, we already know/can predict the change of an ion based on the _____________ it belongs to. family • This is all based on its ____________ Valence _________. electron DRAW DIAGRAM FROM TEXT (pg. 260) • Copy the Bohr-Rutherford • Create a Lewis Dot Diagram • Draw a bohr-Rutherford diagram of sodium and chlorine combining to form sodium chloride. • Draw a lewis-dot structure of the same reaction Sodium Ion, Na+ Chlorine Ion, Cl- HW Q 1-8 on page 261 PERIODIC TABLE WORKSHEET REVIEW Metals are located on the left side of the 1. _______ non-metals located on the right periodic table, with __________ staircase that side. They are separated by a “________” touches the __________. metalloids periods and tell us 2. Horizontal rows are known as ________ shells an element the number of Energy ______ levels _____ or ______ has. Families or groups are vertical ________ columns on the 3. ________ periodic table and tell us how many valence electrons an element has. _________ 4. ATOMS have the same number of Protons as atomic _______, number so their charge is neutral, this they do ______ charge information is detailed in the ______. charge because 5. IONS have a positive or negative _______ they have given up their valence _______ electrons _________ or taken valence electrons from an atom of another element in order to fill/empty their outer energy shell. cations (think the t looks 6. Positive ions are known as _______ anions (has two like a +) while negative ions are called _______ n’s for negative). MAGNESIUM ATOM • Symbol = • Period # = • # of energy levels = • Group # = • # of Valence Electrons = • Member of the _____________ Family • Draw a Bohr-Rutherford Diagram LITHIUM ATOM • Symbol = • Period # = • # of energy levels = • Group # = • # of Valence Electrons = • Member of the _____________ Family • Draw a Lewis-Dot Diagram ARGON ATOM • Symbol = • Period # = • # of energy levels = • Group # = • # of Valence Electrons = • Member of the _____________ Family • Number of Neutrons = • Draw a Bohr-Rutherford Diagram • Symbol = • Period # = • # of energy levels = • Group # = • # of Valence Electrons = • Member of the _____________ Family • Number of Neutrons = • Draw a Lewis Dot diagram FLUORINE ATOM ION REVIEW a) An ION of fluorine is going to mimic (look like) an atom Neon of ______. b) An ION of beryllium is going to mimic an atom of Helium __________________. phosphorus has to gain 3 electrons to c) An ION of ____________ -3 mimic argon. Its ionic charge will be ____. d) An ION of Aluminum _________ has to give up 3 electrons in order to mimic an atom of neon. Its +3 charge will be ___. gain ___ 2 electrons to e) An Ion of Oxygen has to ____ neon Its ionic charge will be ___. -2 mimic _____. CALCIUM ATOM • Symbol = • Atomic # = • # of Protons = • # of Electrons = • Ionic Charge = • Atomic Mass (most common isotope) = • Number of Neutrons = • Draw a Bohr-Rutherford Diagram OXYGEN ION • Symbol = • Atomic # = • # of Protons = • # of Electrons = • Ionic Charge = • Atomic Mass (most common isotope) = • Number of Neutrons = • Draw a Bohr-Rutherford Diagram CHLORINE ION • Symbol = • Atomic # = • # of Protons = • # of Electrons = • Ionic Charge = • Atomic Mass (most common isotope) = • Number of Neutrons = • Draw a Bohr-Rutherford Diagram ALUMINUM ION • Symbol = • Atomic # = • # of Protons = • # of Electrons = • Ionic Charge = • Atomic Mass (most common isotope) = • Number of Neutrons = • Draw a Bohr-Rutherford Diagram POTASSIUM ION • Symbol = • Atomic # = • # of Protons = • # of Electrons = • Ionic Charge = • Atomic Mass (most common isotope) = • Number of Neutrons = • Draw a Bohr-Rutherford Diagram QUESTIONS FROM READING 1. How do atoms become more stable? 2. When metals mix with another metal is it called an ________. 3. When metals mix with non-metals it is called an __________ compound. a) What happens with the electrons in these compounds? 4. When two non-metals mix it is called a ____________ compound. a) What happens with the electrons in these compounds? Pop Quiz 1. 2. 3. 4. 5. What is an ion? What do we call positive & negative ions? Describe ionic compounds /2 Describe molecular compounds /2 What type of compounds are the following… how many atoms in each? • • • • Water – H2O Methane – CH4 Table salt – sodium chloride – NaCl Potassium oxide – K2O 6. What element does a Lithium ion mimic 7. Draw a B-R diagram of a fluorine atom 8. Draw a B-R diagram of a magnesium ion BUILDING MOLECULES THINK ABOUT IT If you were told that an ionic compound formed between a single oxygen ion and a single metal ion, which family would you expect the metal to belong to and why? If you were told that an ionic compound formed between two magnesium ions and a single non-metal ion, what element would you expect to see bonded with the magnesium? If nitrogen gas was going to bond with an alkali metal, how many metal ions would you expect to see bonded? THINK ABOUT IT If you were told that an ionic compound formed btw a single oxygen ion and a single metal ion, which family would you expect the metal to belong to and why? Alkaline earth metal, because their charges balance out… Oxygen is two away from being stable, so it wants 2 electrons… making it a negative 2 (-2) Family two elements have 2 valence electrons, so they want to give away 2 electrons, making them positive 2 (+2) THINK ABOUT IT If you were told that an ionic compound formed between two magnesium ions and a single non-metal ion, what element would you expect to see bonded with the magnesium? Carbon! …or some other family 14 non-metal This is because each magnesium releases two electrons (-2 charge) for a total metal charge of negative 4 (-4) You need a non-metal looking for 4 electrons to balance it THINK ABOUT IT If nitrogen gas was going to bond with an alkali metal, how many metal ions would you expect to see bonded? 3! …nitrogen is 3 away from being stable (full valence shell), so it wants to steal 3 electrons. Since alkali metals only have 1 valence electron, nitrogen must bond with 3 atoms of a alkali metal to fill its valence shell IONIC COMPOUNDS Names & Formulas A ionic compound is made up of positive and negative ions (cation and anion) joined together by ionic bonds. A ionic bond result from a transfer of one or more electrons from one atom to another then joint together by electrostatic forces of attraction. For example, the arrangement of Na+ ions and Cl- ions in a crystal of sodium chloride. Each Na+ ion is surrounded by six neighboring Cl- ions, and each Cl- ion is surrounded by six neighboring Na+ ions. REVIEW Compound consisting of a positively charged (cation) and • Def. negatively charged (anion) ion. metal non-metal • Involves a ___________ + a _____________ joining giving away its ___________ valence together, with the metal _____________ non-metal taking them. electrons and the __________ _________ a particle that has a + or - charge Def. Ion –_________________________________ 2 forms Anion = Negative 1.) _________ Cation = Positive 2.) _________ NAMING Ionic compounds are easily identified by the presence metal (first term). Any time you see a metal as of a ___________ the first term, you should automatically be thinking NUMERICAL IONIC! Additionally, there is never a __________________ reference in the compound name (so no PREFIXES _________________). The nice thing about naming Ionic DO NOT need to worry about molecules is we __________ numbers (subscripts). Example K2O 1)Determine how many elements (each capital letter represents a new element) are present in the compound 2 (_______) and locate them on the periodic table. Is there a metal..? If so it must be a Ionic Compound. 2) Identify which of the elements is the metal (it must go Potassium first). __________________ 3) Identify the non-metal element (it goes 2nd). Oxygen ____________________ 4) Write the name of the metal, than the name of the nonmetal (but change the ending of the non-metal to Potassium _____________ oxide “IDE”). ___________ Try these… Li2O Lithium oxide CaS Calcium sulphide MgF2 Magnesium fluoride Be3P2 Berylium phosphide NaCl K3N Sodium chloride Potassium nitride LiBr Na2O Lithium bromide Sodium oxide WRITING CHEMICAL FORMULAS FOR IONIC COMPOUNDS given/taken and electrical Since the electrons are ____________ charges _______ are present we need to reference the Periodic Table in order to determine how many of each element there is going to be. THE CHARGES MUST BALANCE ____________________________! Step 1: Locate the elements in the Periodic Table- ensure one is a metal, and one is a non-metal. Write down their chemical symbol. Step 2: Determine the “charge” each element carries when its forms an ionic bond (remember: how far from STABLE) Step 3: Backcross the “charges“ to SUBSCRIPTS for each +1 -2 element Rb O Ex. +1 -2 Rb O Rubidium “charges it up” _____ _____ “backcross it down” oxide Rb2O1 Compound Sodium chloride Magnesium nitride Calcium fluoride Francium phosphide CHARGE Na+1 Cl-1 Mg+2 N-3 Ca+2 F-1 Fr+1 P-3 FORMULA NaCl Mg3N2 CaF2 Fr3P MOLECULAR COMPOUNDS Names and Formulas NAMING MOLECULAR COMPOUNDS Molecular compounds are made of 2 or more non• Def. metals only. Non-metal atoms SHARE electrons with each other via COVALENT bonds. • This means there is no taking or giving of electrons, therefore there is no _________ IONS These compounds are… a) Soft, do not form crystals b) Have a low melting point c) Do not dissolve in water d) Do not conduct electricity e) Solids, liquids, and gases easily identified • Molecular compounds are _____________________ by the use of PREFIXES. Anytime you notice a numerical prefix in a compound, you should automatically be thinking MOLECULAR and NONMETAL atoms. Mono Di Tri 1 2 3 Tetra Penta Hexa Hepta 4 5 6 7 Octa 8 EXAMPLE H2O STEP 1: Determine how many elements (each capital letter represents a new element) are present in the compound (_______) and locate them on the periodic table. 2 STEP 2: How many HYDROGEN (H) atoms are there? ________ 2 STEP 3: How many OXYGEN (O) atoms are there? 1 ________ STEP 4: Write the corresponding prefixes first (on the smaller lines), then the name of the element on the larger lines, remember to always change the ending of the second element to “IDE” just like we did yesterday with IONIC compounds. ________ Di _______________ hydrogen Mon _____ ____________ oxygen ide TRY THESE N2O BrI Dinitrogen monoxide Bromine monoiodide ICl2 Iodine dichloride S2Cl2 Disulphur dichloride XeF4 Xenon tetraflouride UF6 ClO2 Chlorine dioxide P2O5 Uranium hexaflouride Diphosphorus pentaoxide REMEMBER: first term never includes mon(o) WRITING CHEMICAL FORMULAS FOR MOLECULAR COMPOUNDS • The ______________ in-front of the element tells PREFIX atoms you how many ______________ (units) of that element there are in the formula. These numbers are to be written as SUBSCRIPTS after the elements symbol. • STEP 1 – write the symbol for each element on the top lines • STEP 2 – write the corresponding prefix number as a subscript (below and after) each elements symbol • Ex. Dinitrogen tetraoxide N2 O ___ 4 ___ TRY THESE Notice that the first term sometimes lacks a prefix… what does this mean again? Nitrogen dioxide NO2 Dinitrogen monoxide N2O Sulphur trioxide SO3 Diphosphorus pentasulphide P2S5 WORKSHEET • Work through all the sections • Try to do it without using your notes to see what sections you need to focus on when it comes time to study IONIC – NAMES KBr Al2S3 Potassium bromide Aluminum sulphide MgO ZnS Magnesium oxide AlCl3 Zinc sulphide Aluminum chloride Ionic – Formulas Magnesium Potassium Chloride Nitride MgCl2 K3N Sodium bromide NaBr Aluminum sulphide Al2S3 Aluminum chloride AlCl3 Molecular – Names P2O5 Diphosphorus pentaoxide SO2 AsBr3 Arsenic Sulphur dioxide tribromide P4O6 CO Tetraphosphorus Carbon monoxide hexaoxide Molecular – Formulas silicon dioxide SiO2 carbon disulfide CS2 diboron tetraphosohorus diphosphorus tetrabromide hexaoxide pentaoxide B2Br4 P4O6 P2O5 Mixed – Names CS2 MgI2 Magnesium Carbon disulphide iodide KF N2O4 Potassium flouride Dinitrogen tetraoxide P4O6 Tetraphosphorus hexaoxide Mixed - Formulas Silicon dichloride SiCl2 magnesium chloride MgCl2 diphosphorus trioxide P2O3 potassium nitride K3N dinitrogen tetraoxide N2O4 • Build the molecule using the ball and stick kits • Build the metal atom using the BR kit… how would you turn it into an ion? • Draw a Bohr-Rutherford diagram of the reaction • Draw a Lewis-dot structure of the reaction END OF CHAPTER 7