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

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

nonmetals: right side of Table; form anions properties: good insulators; gases or brittle solids Br 2 I2I2 S8S8 Ne bromineiodinesulfurneon Regions of the Table (cont.) -- memorize the HOBrFINCl twins (or…Hans and Franz, the ClOBrHIFN twins) “Wer sind sie?” “Die ClOBrHIFN Zwillinge!”

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

Reactivity Trends metal oxide + watermetal hydroxide MgO(s) + H 2 O(l) Mg(OH) 2 (aq) metal oxide + acid salt + water CaO(s) + 2 HNO 3 (aq) Ca(NO 3 ) 2 (aq) + H 2 O(l) metal + nonmetal salt 2 Al(s) + 3 Br 2 (l) 2 AlBr 3 (s) (i.e., a “basic” oxide)

Reactivity Trends (cont.) nonmetal oxide + water acid CO 2 (g) + H 2 O(l) H 2 CO 3 (aq) (i.e., an “acidic” oxide) nonmetal oxide + base salt + water CO 2 (g) + 2 KOH(aq) K 2 CO 3 (aq) + H 2 O(l)

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 2 NaCl(l) 2 Na(l) + Cl 2 (g)

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

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

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

Halogens -- At isn’t considered to be a halogen; little is known about it -- at 25 o C, F 2 and Cl 2 are gases, Br 2 is a liquid, I 2 is a solid -- their exo. reactivity is dominated by their tendency to gain e – -- Cl 2 is added to water; the HOCl produced acts as a disinfectant -- HF(aq) = weak acid; HCl(aq) HBr(aq) HI(aq) = strong acids 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.

professional-grade Rn detector 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 (KrF 2 ); Xe has a few (XeF 2, XeF 4, XeF 6 ) Fan for Rn mitigation

Ca atomCa 2+ ion Cl atom Cl – ion 20 p + 20 e – 20 p + 18 e – 17 p + 17 e – 17 p + 18 e – Ca Ca 2+ Cl Cl – Ionic Radius Cations are _______ than parent atoms; anions are ______ than parent atoms. EX. Compare the sizes of Fe, Fe 2+, and Fe 3+. Then compare Br with Br –. smaller larger Fe > Fe 2+ > Fe 3+ Br – > Br

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

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