Chapter 2PowerPoint PresentationSlide 3Slide 4Slide 5MetalsNonmetalsMetalloidsSlide 9Slide 10Slide 11Slide 12Slide 13What oxidation state is preferred by elements in these groups?§2.6 Subatomic ParticlesA Lot of Empty SpaceAtomic SymbolsIsotopesIsotopes and Ions§2.8 Atomic MassSlide 21Calculate the average atomic mass of Ge.The Mass Spectrometer§2.9 The Mole§2.9 How Big is a Mole?Slide 26Slide 27Mole Problem SolvingAvogadro’s NumberAtoms and elementsChapter 2We cover only §2.6 – 2.9periodsgroupsmetalsnonmetalsmetalloidsMetalsSolids at room temperature (except Hg)ShinyConduct heat and electricityMalleableDuctileLose electrons to form cations in reactionsAbout 75% of all elementsFound to the left of the periodic tableColorless (except Cu and Au)NonmetalsCan exist in all 3 statesPoor conductors of heat and electricitySolids are brittleGain electrons in reactions to become anionsFound to the right of the periodic table (except H)S(s)Br2(l)Cl2(g)MetalloidsAll metalloids are:oshiny (like metals)obrittle (like nonmetals)osemiconductorsthey gain electrons (like nonmetals)they lose electrons (like metals).Metalloidsarsenicboronsiliconantimonytelluriumgermaniumliquidsat 25 °Cgasesat 25 °Cmain group elementstransition metalslanthanidesactinidesnoble gasesalkali metalscoinage metalshalogensalkaline earth metalsWhat oxidation state is preferred by elements in these groups?+1+2Cu +1, +2Ag +1Au +1, +3-10-2§2.6 Subatomic ParticlesA Lot of Empty SpaceIf the atomic nucleus were the size of this ball bearing, the atom would be the size of this stadium.Atoms have so much empty space that 50 trillion neutrinos pass through a human being every second.Atomic SymbolsAtomic Number (Z):Equal to the number of protons in the nucleusDefines the elementMass Number (A):Neutrons plus protonsIsotopes have different number of neutronsAtomic Symbol (X):XAZIsotopesAll isotopes of an element have:othe same chemical reactivity;othe same number of protons;odifferent numbers of neutrons, and ∴ different masses.>90% of known isotopes are radioisotopes, and every element has at least one radioisotope.Identify an isotope by mass number (protons + neutrons).XA1ZXA2ZIsotopes and IonsSymbol # Protons # Neutrons # Electrons Net Charge26 33 +376 54 -285 125 86Fe59263+23Te128522-52At21085--1§2.8 Atomic MassMeasuring mass is relative. To measure an object’s mass is to compare it to a cylinder in France.12C, defined as exactly 12 atomic mass units (amu), is the reference for atomic masses. ∴ 1 amu = [12C mass] / 1212§2.8 Atomic MassAtomic masses on the periodic table are averages. No actual U atom has a mass of 238.03 amu. Average atomic mass is calculated from the mass and abundance of each isotope.92238.03UCalculate the average atomic mass of Ge.Isotope Atomic Mass Relative Abundance70Ge 69.924 amu 20.5 %72Ge 71.922 amu 27.4 %73Ge 72.923 amu 7.78 %74Ge 73.921 amu 36.5 %76Ge 75.921 amu 7.83 %= (69.924 amu)(0.205)+ (71.922 amu)(0.274)+ (72.923 amu)(0.0778)+ (73.921 amu)(0.365)+ (75.921 amu)(0.0783) = 72.6 amu32Ge72.64The Mass Spectrometer34.9689 amu75.77%36.9659 amu24.23%§2.9 The MoleA mole (mol) ≡ the number of atoms in exactly 12 g of pure 12C. The mole allows (grams) ⇆ (number of particles) conversions.1 mol = 6.02214 × 1023 particles6.02214 × 1023 is Avogadro’s number or NA§2.9 How Big is a Mole?All the human beings on the planet put together have roughly 1 mole of bacteria in their guts.The University of Hawai’i estimated there are 7.5 × 1018 grains of sand on Earth.The journal Nature estimated there are 3 × 1023 stars in the universe.One mole of periods (.) lined up side by side would equal the radius of our galaxy.One mole of seconds ≈ 1 quadrillion years1 mole = 6.02214 × 1023§2.9 The MoleAn element’s atomic mass provides 2 pieces of information:1. The average mass of an atom:1 Au atom = 196.97 amu2. The mass in grams of 1 mole of an atom:1 mol Au = 196.97 g79Au196.97With the mass of a pure compound we can find the number of atoms in the sample, and vice versa.§2.9 Counting Atoms by Molesmass molesnumber of atomsatomic massormolar massAvogadro’s numberMole Problem SolvingWhat is the mass of 13 atoms of rhodium?As expected for such a small number of atoms, the mass is miniscule.13 atoms Rh 1 mol Rh6.022 ⨯ 1023 atoms Rh102.9 g Rhmol Rh= 2.221 ⨯ 10-21 g RhAvogadro’s NumberIf 100 (short) tons of Cu were used to make the Statue of Liberty, how many atoms does it contain? 1 kg = 2.205 lb.100 tons2000 lb1 ton1 kg2.205 lb = 9 × 1029 atoms 103 g1 kg1 mol63.55 g6.022 × 1023 atoms1