metals: left side of Table; form cationsproperties:

Regions of the Table

ductile(can pullinto wire)

malleable(can hammerinto 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

Br2I2S8Nebromineiodinesulfurneon

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 metalsand nonmetals

properties: in-between those of metalsand 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 + 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)

(i.e., a“basic”oxide)

Reactivity Trends (cont.)

nonmetal oxide + water acid CO2(g) + H2O(l) H2CO3(aq)

(i.e., an“acidic”oxide)

nonmetal oxide + base salt + water

CO2(g) + 2 KOH(aq) K2CO3(aq) + H2O(l)

Group TrendsAlkali 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) + Cl2(g)

-- react with hydrogen to form metal hydrides:

-- react with water to form metal hydroxides:

-- react w/O2: Li yields Li2O, others yield (mostly) peroxides (M2O2)

2 M(s) + H2(g) 2 MH(s)

2 M(s) + 2 H2O(l) 2 MOH(aq) + H2(g)

2 M(s) + O2(g) M2O2(s)

Potassium in water, forming flammable hydrogenand soluble potassium hydroxide.

Alkaline-Earths

-- not as reactive as alkalis (two e– to lose)

-- Ca and heavier ones react w/H2O to form metal hydroxides

-- MgO is a protective oxide coating around substrate Mg

Ca(s) + 2 H2O(l) Ca(OH)2(aq) + H2(g)

compared to alkalis: harder, denser, higher MPs

Mg ribbon MgO

The Hindenburg

Hydrogen

-- a nonmetal, but belongs to no family

-- reacts w/other nonmetals to form molecular (i.e., covalent) compounds

(She was scuttled inJune 1919, along

with 71 otherGerman ships.)

(She burned upin May 1937,

killing36 passengers.)

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–

-- Cl2 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 ahalogen is mixed with anoble gas to fill halogenlamps. The halogen setsup an equilibrium withthe tungsten filamentto prevent the heatedtungsten from being

deposited on theinside of the bulb.

professional-gradeRn 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 (KrF2); Xe has a few (XeF2, XeF4, XeF6)

Fan forRn mitigation

Ca atom Ca2+ ion Cl atom Cl– ion 20 p+ 20 e–

20 p+ 18 e–

17 p+ 17 e–

17 p+ 18 e–

Ca Ca2+ Cl Cl–

Ionic RadiusCations are _______ than parent atoms;anions are ______ than parent atoms.

EX. Compare the sizes of Fe, Fe2+, and Fe3+.

Then compare Br with Br–.

smallerlarger

Fe > Fe2+ > Fe3+

Br– > Br

electronegativity: the tendency fora bonded atom toattract e– to itself

up and to-the-right.

electronegativity increases

Electronegativity

Electronegativity increases going...

Most electronegative element is... fluorine (F).

Linus Paulingquantified the

electronegativityscale.

“Oh, man… I forgot which ones themost electronegative elements are.”

“Shee-oot… Ow teh ye…

FO’ NCl.”

F = 4.0O = 3.5

N = Cl = 3.0

C = 2.5 H = 2.1Others: