Learning objectives: After completing this unit of study, you should be able to: • An element’s location on the periodic table gives an indication of its physical and chemical properties. • Elements on the Periodic Table are arranged in order of increasing atomic number. • Elements are classified as metals, nonmetals and metalloids based on their properties and location on the periodic table. • Groups 1, 2, and 13-18 have the same number of valence electrons in the group, and therefore have similar chemical properties. Helium is the exception to this. • Each group shows trends in atomic radius, ionic radius, Electronegativity, first ionization energy, and metallic and nonmetallic properties. • Each period shows trends in atomic radius, Electronegativity, first ionization energy, and metallic and nonmetallic properties. • When an element becomes an anion by gaining electrons, the radius increases. • When an element becomes a cation by losing electrons, the radius decreases. • Some elements exist as two or more forms in the same phase due to differences in molecular or crystal structures, and therefore have different chemical and physical properties. These are called Allotropes. Carbon has the allotropes coal, graphite, diamond, and fullerenes. Oxygen has the allotropes O2 & O3. Learning Guide 1: P.T. Basics 1. Dimitri Mendeleev organized the 1st periodic table by atomic mass. 2. Mosley re-organized the periodic table by atomic number. 3. This was better because there are places on the periodic table that mass goes down, but atomic number ALWAYS INCREASES BY 1. 4. Modern Periodic Law states that elements are organized by atomic number, and properties are determined by number of valence electrons. Learning Guide 1: P.T. Basics Atomic Mass Oxidation States (charge) Symbol Atomic Number Electron Configuration Learning Guide 1: P.T. Basics 6. A PERIOD is a horizontal row on the periodic table. 7. All elements in a period have valence electrons in the same ring. 8. The number of valence electrons go up by one as you go cross a period. Metals, Metalloids & Nonmetals: Learning Guide 1: P.T. Basics 9. Metals are located to the left and below the staircase line. 10. Nonmetals are located to the right and above the staircase line. 11. Metalloids (Semimetals) are located bordering the staircase line. States of Matter at RT Learning Guide 1: P.T. Basics 12. The majority of the elements are SOLID at room temperature. 13. There are 2 elements that are liquids at room temperature: Bromine (Br) & Mercury (Hg). 14. The gases at room temperature are : Hydrogen (H), Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Rn), Flourine (F), Oxygen (O), Nitrogen (N), Chlorine (Cl) Learning Guide 1: P.T. Basics 15. A GROUP is a vertical column on the periodic table. 16. Another name for a group is a family. 17. All elements of a group have the same number of valence electrons. 18. All members of a group have similar reactivity. Learning Guide 1: P.T. Basics Symbol Name Atomic # Period Group Pb Potassium 45 Iron 3 17 Complete chemdo 1 Metals, Metalloids & Nonmetals: METAL NONMETAL Located to the left & below the staircase line Located to the right above the staircase line • • • • • • • • • • • • • • Solid ( except Hg(l) ) Luster (shiny) Malleable ( flattens) Ductile (wire) Conducts electricity Conducts heat Hi density Soft Solid, liquid or gas Dull Brittle Hard Don’t conduct electricity Don’t conduct heat Loses electrons Gains electrons Form cations ( + ion) Form anion (- ion) Ions smaller than atom Ions bigger than atom Good conductor of heat & electricity Poor conductor of heat & electricity Lo Ionization Energy Hi Ionization Energy Lo Electronegativity Hi Electronegativity Most active metal lower left Most active nonmetal upper right Learning Guide 2: M/NM/SM 1. Nonmetal ions are larger than the atoms from which they are formed from because they gain electrons. 2. Metal ions are smaller than the atoms from which they from because they lose electons. Learning Guide 2: M/NM/SM 3. Transition metals are located in groups 3-12. 4,,The transition metals have multiple (more than one) oxidation states. 4. 2 unique characteristics are multiple oxidation states and colored solutions in water. Learning Guide 2: M/NM/SM 5. Metalloids are elements that have properties of both metals and nonmetals. 6. Metalloids border the staircase line. Learning Guide 2: M/NM/SM 7. Noble gases are found in group 18. 8. They are unique because they do not react with other elements (they are snobs). Learning Guide 2: M/NM/SM 9. Allotope: elements that exist as two or more forms in the same phase due to differences in molecular or crystal structures, and therefore have different chemical and physical properties. 10. a. Carbon (C) has the allotropes coal, graphite, diamond, and fullerenes. b. Oxygen has the allotropes O2 & O3. Phosphorus has 3 allotropes Allotropes of Carbon: Metals, Metalloids & Nonmetals: Metals, Metalloids & Nonmetals: Property METAL to left and below staircase line 2/3 of elements SEMIMETAL border staircase line NONMETAL To right & above staircase line 1/3 of elements LOCATION yes maybe no, dull yes Maybe no yes Maybe No, hard & brittle solid solid, liquid & gas LUSTER – SHINY? CONDUCTIVE OF HEAT & ELECTRICITY? MALLEABLE – CAN BEND WITHOUT BREAKING? solid, except Hg(l) PHYSICAL STATE AT RT? Cu, Au, Ag, Pt B, Ge, Si, Sb, Te, At F, C, N, O, Cl… IMPORTANT EXAMPLES: # OF VALENCE ELECTRONS TENDENCY TO LOSE OR TO GAIN ELECTRONS? GENERAL ATOMIC STRUCTURE ARE IE & EN HIGH OR LOW? 1, 2, 3, tend to lose e- forming cations, getting smalller less than 4 valence electrons Low 3, 4,,5 Can gain or lose Around 4 valence electrons Medium 5, 6, ,7 tend to gain e- , forming anions, getting larger more than 4 valence electrons High Metal & Nonmetal LAB METALS • Luster: shiny • Mostly solid • Soft: Malleable – can flatten easily Ductile – can be a wire • Conducts heat & electricity (Cu wire , Ag & Au jewelry) • Reactive ( bubbles w/ HCl, darkens w/ CuCl2) NONMETALS • Dull (not shiny) • Can be solid or liquid or gas • Hard & Brittle ( crushes to a powder easily) • Does NOT conduct • Does NOT react Which elements that you tested were METALS? LIST: Support: Which elements that you tested were NONMETALS? LIST: Support: Which elements that you tested were METALLOIDS? LIST: Support: Complete chemdo 2 Groups/Families of the Periodic Table Nuclear Charge • The charge of the nucleus • The number of protons = atomic number • Greater nuclear charge means greater attraction of nucleus on the electrons • Means smaller radius, harder to lose e- (IE) easier to gain e- (e-neg) Shielding • Kernel electrons interfere with the nuclear attraction for valence electrons. • More energy levels mean that it is easier to remove an e- and harder to gain an e-, because protons are shielded by the kernel e- in between them. Ionization Energy • The amount of energy needed to remove the outermost electron. • More IE = harder to remove an electron • Less IE = easier to remove an electron Learning Guide 3: Trends in Groups & Families nuclear charge 4. As you go left to right across a period, nuclear charge increases, electrons are stronger attracted and more energy is required to remove them Learning Guide 3: Trends in Groups & Families nuclear charge • 5. As you go top to bottom down a group, valence elevtrons are farther from the nuclesu and it is easier energy is required to remove them Atomic Radius DEF: ½ the distance between 2 atoms OR THE RADIUS OF AN ATOM Learning Guide 3: Trends in Groups & Families 7. As you go left to right across a period atomic radius decreases. 8. As nuclear charge increases as you go left to right across a period, the number of protons increase, pulling tighter on electrons and making the radius smaller. Learning Guide 3: Trends in Groups & Families 9. Shielding effect across a period is constant because balance electrons are in the same energy level in the same period. Li Be B C N O F Ne e- config: 2-1 2-2 2-3 2-4 2-5 2-6 2-7 2-8 Across a period sheilding has NO EFFECT!! Learning Guide 3: Trends in Groups & Families 10. As you go top to bottom down a group atomic radius increases. 11. The number of occupied energy levels increases as you go top to bottom down a group. 12. Shielding causes atomic size to INCREASE as atomic number increases down a group. Learning Guide 3: Trends in Groups & Families 13. ION: a charged part of an atom, resulting from the loss or gain of an electron. 14. Ionic Radius: LOSS of electron ion is SMALLER than atom GAIN of electron ion is BIGGER than atom Learning Guide 3: Trends in Groups & Families 15. Metals tend to lose electrons to form an ion with a radius that is smaller than the atom. 16. Nonmetals tend to gain electrons to form an ion with a radius that is larger than the atom. Learning Guide 3: Trends in Groups & Families 17. Electronegativity: A measure of how easily an atom gain gain (attract) electrons. Bigger EN number: easier to gain LOOK ON REF. TABLE S!!!!!!!! 18. Flourine has highest EN value of 4.0 19. Francium has lowest EN of 0.7 Remember ionic radius??? • When an atom forms an ION that is POSITIVE, the IONIC RADIUS is LESS THAN ATOMIC RADIUS, because it LOSES ELECTRONS • When an atom forms an ION that is NEGATIVE, the IONIC RADIUS is BIGGER THAN ATOMIC RADIUS, because it GAINS ELECTRONS Bohr models of 3Li, 9F, 87Fr Pg 14-17 notepacket: • Atomic Radius – distance from nucleus to valence electron • Ionization Energy: energy required to remove the outermost electron • Electronegativity – a measure of ability to gain an electron Periodicity: • FOLLOWS A PATTERN • There are general trends in properties as you move left to right across a period. • There are general trends in properties as you move top to bottom down a group. Periodic Trend in Number of Valence Electrons 1 (IA) 2 (IIA) 13 (IIIA) 14(IVA) 15 (VA) 16 (VIA) 17 (VIIA) 18 (VIIIA) Periodic Trend in Number of Valence Electrons 1.) What is the trend in valence electron number as you go from left to right across any period on the table? 2.) What is the trend in the valence electron number as you go down any group from top to bottom? 3.) What is the trend in the number of energy levels as you go down any group from top to bottom? 4.) Use your answers to #2 & 3 to write a statement explaining the relationship between number of valence electrons and the number of energy levels. Periodic Trend in Atomic Radius 1 (IA) 2 (IIA) 13 (IIIA) 14(IVA) 15 (VA) 16 (VIA) 17 (VIIA) 18 (VIIIA) Periodic Trend in Atomic Radius 1.) What is the trend in atomic radii as you go from left to right across any period on the table? 2.) What is the trend in the number of protons (nuclear charge) as you go from left to right across any period on the table? 3.) Use your answers to #1 & 2 to write a statement explaining the relationship between atomic radii and nuclear charge (# of protons). 4.) What is the trend in atomic radii as you go down any group from top to bottom? 5.) What is the trend in the number of energy levels as you go down any group from top to bottom? 6.) Use your answers to #4 & 5 to write a statement explaining the relationship between atomic radii and the number of energy levels. Ionization Energy: energy required to remove the outermost electron 1 (IA) 2 (IIA) 13 (IIIA) 14(IVA) 15 (VA) 16 (VIA) 17 (VIIA) 18 (VIIIA) Periodic Trend in Ionization Energy 1.) What is the trend in ionization energy as you go from left to right across any period on the table? 2.) What is the trend in the number of protons (nuclear charge) as you go from left to right across any period on the table? 3.) Use your answers to #1 & 2 to write a statement explaining the relationship between ionization energy and nuclear charge (# of protons). 4.) What is the trend in ionization energy as you go down any group from top to bottom? 5.) What is the trend in the number of energy levels as you go down any group from top to bottom? 6.) Define shielding: 7.) Use your answers to #4 & 5 to write a statement explaining the shielding effect on onization energy . Electronegativity – a measure of ability to gain an electron 1 (IA) 2 (IIA) 13 (IIIA) 14(IVA) 15 (VA) 16 (VIA) 17 (VIIA) 18 (VIIIA) Periodic Trend in Electronegativity 1 (IA) 2 (IIA) 13 (IIIA) 14(IVA) 15 (VA) 16 (VIA) 17 (VIIA) 18 (VIIIA) Periodic Trend in Electronegativity 1.) What is the trend in electronegativity as you go from left to right across any period on the table? 2.) What is the trend in the number of protons (nuclear charge)as you go from left to right across any period on the table? 3.) Use your answers to #1 & 2 to write a statement explaining the relationship between electronegativity and nuclear charge (# of protons). 4.) What is the trend in electronegativity as you go down any group from top to bottom? 5.) What is the trend in the number of energy levels and shielding as you go down any group from top to bottom? 6.) Use your answers to #4 & 5 to write a statement explaining the shielding effect of number of energy levels on electronegativity. Periodic Trend in Melting and Boiling Points Data Table 2: Boiling Points and Melting Points of the First 20 Elements Atomic Number 1 2 3 4 5 BP (0C) -252 -269 1327 2507 2527 Mp (0C) -259 -272 179 1287 2037 Atomic Number 6 7 8 9 10 BP (0C) 4347 -196 -183 -188 -246 Mp (0C) 3470 -210 -219 -218 -248 Atomic Number 11 12 13 14 15 BP (0C) 889 1117 2327 2677 280 Mp (0C) 97 650 659 1407 44 Atomic Number 16 17 18 19 20 BP (0C) 445 -34 -186 757 1487 Mp (0C) 119 -101 -189 64 851 Graph Title: Periodic Trend in Melting Point and Boiling Point Y-axis: start at -300, end at 4800, each “bold” line increases by 300. Label: TEMPERATURE (oC) X-axis: _______ start at 0, end at 20, each “bold” line increases by 2 Label: ATOMIC NUMBER Chem Do 3 graph Y-axis: start at 50, increase by 10, stop at 220 X-axis : start at 10, count by .5, stop at 18 Be sure to * write a good title (1pt) * label each axis (1 pt each) * make a key describing the colors (1 pt) Chem Do 3b graphs #6: “Trend in atomic radius down group 2” Y-axis: start at 100, increase by 10, stop at 270 X-axis : start at 0, count by 5, stop at 90 #7: “Trend in ionization energy down group 1” Y-axis: start at 200, increase by 100, stop at 1800 X-axis : start at 0, count by 5, stop at 90 Complete chemdos 3a & 3b Periodic Properties of Elements Alkali Metals Location: group 1 Characteristic Elements: Na, K, Rb, Cs, Fr Reactivity: most active metals (Fr is THE most active metal), never found free in nature, electrolysis of fused salts. lo IE & electronegativity lose e-, IR<AR Alkaline Earth Metals Location: group 2 Characteristic Elements: Be, Mg, Ca, Sr, Ba, Ra Reactivity: very hi, but less than group 1. Also never found free in nature, electrolysis of fused salts lo IE & electronegativity lose e-, IR<AR Transition Metals Location: groups 3-12 Characteristic Elements: Fe, Cu, Cr, Au, Ag, Pt, Pb, Mn, Co… Special Characteristics: hard solids with hi MP, less reactive than groups 1 & 2 multiple oxidation states due to more than one energy level being filled at a time cause: colored solutions in water Why do transition metals produce colored solutions? MULTIPLE OXIDATION STATES! Look at: Fe Cr Ni Cu Alloy Def: solid mixture of metals (homogeneous mixture, ratio can vary) Examples: brass – mixture of zinc & copper bronze – copper & tin sterling silver – silver & copper Halogens Location: group 17 Characteristic Elements: F, Cl, Br, I, At Reactivity: most reactive NONMETALS, Also never found free in nature, electrolysis of fused salts or chemically hi IE & electronegativity (F is highest of 4.0) gain e-, IR>AR Exhibit all 3 states of matter (F & Cl (g), Br (l), I & At (s)) Noble Gases Location: group 18 Characteristic Elements: He, Ne, Ar, Kr, Xe, Rn Reactivity: monatomic because full valence shell of 8 e- (He is full w/ 2 e-) therefore, do not react exception: Xe & Ar w/ F BP increases with increasing size Use the next slide to label the blank periodic table found on page 18 of your packet. Label the name of and color the group(s) as follows: ALKALI METALS - RED ALKALINE EARTH METALS – ORANGE TRANSITION METALS – YELLOW METALLOIDS-GREEN HALOGENS- BLUE NOBLE GASES - PURPLE Groups/Families of the Periodic Table Learning Guide 4: Families of Elements 1. The metals in group 1 are called alkali metals. 2. The metals in group 2 are called alkaline earth metals. 3. Group 1 and 2 metals easily lose electrons and they are never found free in nature. 4. Elements in group 1 & 2 have low IE & low EN. 5. Elements in group 1 form ions with a +1 charge and elements in group 2 form ions with a -1 charge. Learning Guide 4: Families of Elements 6. Reactivity increases as you go down the groups 1 & 2 top to bottom. 7.The most reactive metal is Fr (Francium). 8. Metallic character increases as you go down groups 14,15, 16. (nonmetal metalliodmetal) 9. The nonmetals in groups 14, 15, 16 are C, N, P, O, S, Se. 10. The metalliods in groups 14, 15, 16 are Si, Ge, As, Sb, Te, Po. Learning Guide 4: Families of Elements 11. The metals in groups 14, 15, 16 are Sn, Pb, Bi, Po. 12. Group 17 elements are called halogens. 13. Group 17 is special because it has all three states of matter: solid (I, At), liquid (Br) and gas (F, Cl. 14. The most reactive element of group 17 is F (flourine). Learning Guide 4: Families of Elements 15. Group 18 elements are called noble gases. 16. Oops 17. Because they don’t react with other elements – they are snobs. 18. Elements in the same group/family have similar chemical properties because they have the same number of valence electrons. Learning Guide 4: Families of Elements 19. The number of valence electrons is important because they are the electrons that are involved in forming bonds. 20. Each unpaired electron is a bonding site. 21. When determining similar reactivity and trends, elements within the same group will react the same, due to the same number of valence electrons. Learning Guide 4: Families of Elements For example: a.) if Na (group 1) & Cl (group 17) react to form NaCl Then K (group 1) & Cl (group 17) will form KCl Learning Guide 4: Families of Elements For example: a.) if Mg (group 2) & Cl (group 17) react to form MgCl2 Then Ca (group 2) & Cl (group 17) will form CaCl2 Complete chemdo 4 Reactivity of Metals Demo (pg 21) Complete the following data table by making observations about the physical appearance of the metals shown by the instructor. Include luster(shine), hardness or softness, reaction with air. Physical properties of group IA & IIA metals IA (1) IIA (2) Na Mg K Ca Observe the reactions of each metal as the instructor places it in water. Record your observations below. Na K Reactivity of group IA (1) & IIA (2) metals in water IA (1) IIA (2) Mg Ca Video demos of alkali metals Video of sodium in water Video if potassium in water Video of Cesium in water Video of Francium in water Learning Guide 5: Reactivity 1. As you look down a group the electron configuration gains one more number (ring). 2. As you look down a group the number of valence electrons stays the same. 3. Elements in the same group have similar chemicals properties because they have the same number of valence electrons. Learning Guide 5: Reactivity 4. As you go down a group the elements may change from nonmetal metalloid metal. 5. The metallic characteristics increase as you go down a group. 6. As you go left to right metallic characteristics decrease. 7. Hydrogen may not be considered a member of group 1 because it can also acts as a nonmetal in group 17. Learning Guide 5: Reactivity 8. Hydrogen can have +1 or -1 oxidation states. 9. Group 1 is named alkali metals. 10. Group 2 is named alkaline earth metals. 11. Group 1 & 2 elements are characterized by low electronegativity and high reactivity. 12. Group 1 is more reactive than group 2. Learning Guide 5: Reactivity 13. Groups 14, 15, 16 progress from nonmetal metalloid metal. 14. Group 17 is named halogens. 15. Group 17 is the only group that contains solid, liquid and gas. 16. Group 17elements are characterized by high EN and high IE. Learning Guide 5: Reactivity 17. Since small nonpolar molecules are held in solid and liquid phases by weak forces, BP & MP increase as the number of electrons increase. 18. Groups 1, 2, & 17 are never found free in nature because they are too reactive. They will react with anything in the air quickly. 19. They are reduced to their free state by electrolysis: zap them w/ lots of electricity!! Learning Guide 5: Reactivity 20. Group 18 elements were once called the inert gas group because they do not react with other elements, due to a gull valance shell of 8 electrons. They are now called noble gases. 21. The trend in BP going down group 18 is increasing (look it up on ref. table S: He BP = 4K Rn Bp =211 K Complete Chemdo 5 Never found free in nature: groups 1, 2, 17 Colored ions due to multiple oxidation states: transition metals Strongest Metal: Fr Strongest Nonmetal: F Liquids at RT: Hg & Br Periodic Table Review • Trends across a period L R, due to increased nuclear charge (val. e- in same energy level) pulling valance electrons closer/tighter – Decreased AR, Increased IE & EN • Trends down a group (top bottom), due to shielding: more energy levels between nucleus and valence electrons – Increased AR, Decreased IE & EN