metals : left side of Table; form cations

1. lustrous (shiny) malleable (can hammer into shape) ductile (can pull into wire) good conductors (heat and electricity) Regions of the Table metals: left side of Table; form cations properties:

2. -- Because of their low ionization energies, they are often oxidized in reactions. (i.e., they lose e–) -- Metallic character of the elements increases as we go down-and-to-the-left. increasing metallic character

3. Regions of the Table (cont.) nonmetals: right side of Table; form anions good insulators; gases or brittle solids properties: neon sulfur iodine bromine Ne S8 I2 Br2 -- memorize the HOBrFINCl twins (or…Hans and Franz, the ClOBrHIFN twins) “Wer sindsie?” “Die ClOBrHIFNZwillinge!”

4. nonmetals metals computer chips Si and Ge Si and Ge Regions of the Table (cont.) metalloids (semimetals): “stair” between metals and nonmetals (B, Si, Ge, As, Sb, Te, Po, At) properties: in-between those of metals and nonmetals; “semiconductors” computer chips

5. (i.e., a “basic” oxide) Reactivity Trends metal oxide + water metal hydroxide MgO(s) + H2O(l) Mg(OH)2(aq) metal oxide + acid salt + water CaO(s) + 2 HNO3(aq) Ca(NO3)2(aq) + H2O(l) metal + nonmetal salt 2 Al(s) + 3 Br2(l) 2 AlBr3(s)

6. (i.e., an “acidic” oxide) Reactivity Trends (cont.) nonmetal oxide + water acid CO2(g) + H2O(l) H2CO3(aq) nonmetal oxide + base salt + water CO2(g) + 2 KOH(aq) K2CO3(aq) + H2O(l)

7. 2 NaCl(l) 2 Na(l) + Cl2(g) Group Trends Alkali Metals -- the most reactive metals (one e– to lose) -- obtained by electrolysis of a molten salt e.g., chloride ion is oxidized and sodium ion is reduced

8. -- react with hydrogen to form metal hydrides: 2 M(s) + H2(g) 2 MH(s) -- react with water to form metal hydroxides: 2 M(s) + 2 H2O(l) 2 MOH(aq) + H2(g) -- react w/O2: Li yields Li2O, others yield (mostly) peroxides (M2O2) 2 M(s) + O2(g) M2O2(s) Potassium in water, forming flammable hydrogen and soluble potassium hydroxide.

9. Alkaline-Earths -- not as reactive as alkalis (two e– to lose) compared to alkalis: harder, denser, higher MPs -- Ca and heavier ones react w/H2O to form metal hydroxides Ca(s) + 2 H2O(l) Ca(OH)2(aq) + H2(g) -- MgO is a protective oxide coating around substrate Mg Mg ribbon MgO

10. Hydrogen -- a nonmetal, but belongs to no family -- reacts w/other nonmetals to form molecular (i.e., covalent) compounds The Hindenburg (She burned up in May 1937, killing 36 passengers.) (She was scuttled in June 1919, along with 71 other German ships.)

11. -- HF(aq) = weak acid; HCl(aq) HBr(aq) HI(aq) = strong acids Halogens -- At isn’t considered to be a halogen; little is known about it -- at 25oC, F2 and Cl2 are gases, Br2 is a liquid, I2 is a solid -- their exo. reactivity is dominated by their tendency to gain e– A small amount of a halogen is mixed with a noble gas to fill halogen lamps. The halogen sets up an equilibrium with the tungsten filament to prevent the heated tungsten from being deposited on the inside of the bulb. -- Cl2 is added to water; the HOCl produced acts as a disinfectant

12. professional-grade Rn detector Fan for Rn mitigation Noble Gases -- all are monatomic; have completely-filled s and p orbitals -- He, Ne, and Ar have no known compounds; Rn is radioactive -- Kr has one known compoud (KrF2); Xe has a few (XeF2, XeF4, XeF6)

13. Ca Cl Cl– Ca2+ Ionic Radius smaller Cations are _______ than parent atoms; anions are ______ than parent atoms. larger Ca atom Ca2+ ion Cl– ion Cl atom 17 p+ 20 p+ 17 p+ 20 p+ 17 e– 18 e– 20 e– 18 e– EX. Compare the sizes of Fe, Fe2+, and Fe3+. Then compare Br with Br–. Fe > Fe2+ > Fe3+ Br– > Br

14. Linus Pauling quantified the electronegativity scale. electronegativity increases Electronegativity electronegativity: the tendency for a bonded atom to attract e– to itself Electronegativity increases going... up and to-the-right. Most electronegative element is... fluorine (F).

15. “Oh, man… I forgot which ones the most electronegative elements are.” F = 4.0 O = 3.5 N = Cl = 3.0 “Shee-oot… Ow teh ye… FO’ NCl.” H = 2.1 Others: C = 2.5