CHE 2C Properties

alkaline earth metals

Be, Mg, Ca, Sr, Ba, Ra (radioactive)

alkaline earth metal properties

doesn’t include Be

+2 oxidation state

low density, mp, and bp

insoluble

produced by reduction

Be

higher mp

harder

unreactive to air & water

smaller

high ionization energy

tends to be covalent, not ionic

limited tendency to form Be^+2

BeCl = unique structure

Group 13 (Icosagens)

Al, Ga, In, Tl

Group 13 properties

common oxidation states: +1, +3 (inert pair effect)

relatively soft metals

good conductors

relatively reactive

form dimers (especially Al)

Al

most abundant metal in Earth’s crust

strong, light

forms alumina (Al2O3)

formed by electrolysis

reducing agent

Ga

Gallium

obtained by smelting

higher density liquid state like water

attacks metals by diffusing into their crystal lattice

applications: electronics, LEDs, transistors, semiconductors, amplifiers, solar cells

In

Indium

squeals when bent

can be a strong oxidizing/reducing agent depending on ox. state

applications: electrodes in LCDs and touch-screens, coatings, alloys, solders, electrical components, transistors, optical devices

Tl

Thallium

name = Greek word “twig”

very toxic (poison historically)

applications: superconductor, lamps, electronics, photoelectric cells, pharmaceutical industry, glass manufacturing

inert pair effect

occurs in Group 13, 14, 15, 16

expected charge of +3, +4, +5, +6 respectively

two s-electrons (ns2) do not become involved in the chemistry of the atom, and become inert similar to core electrons

• this is the reason p-electrons are removed from the cation

nonmetal charge

negative

metal charge

positive charge (groups 13-16 have two different charges because of inert pair effect)

semimetals

act as both, both positive and negative charges

Helium

escapes atmosphere but found trapped in some locations

fuel diluent (H2 and O2 are too high of a flame risk, so He is used to dilute gases for safety)

superfluidity: does not experience viscosity

multiple liquid phases are possible

neon

odorless, colorless

emits light under current

argon

3rd most common gas that comprises air

applications: inert gas for welding, some light bulbs, radioactive dating (K-Ar)

krypton

Hexagonal close-packed crystal structure

product of fission

used to measure worldwide nuclear activity

xenon

more readily oxidized than other noble gases

halogen lamps

flash tubes

radon

found in some hot springs

connected to lung cancer

product of radioactive processes deep in the earth

Group 17 (Halogens)

F, Cl, Br, I, At

Group 17 properties

produced industrially by electrolysis or oxidation

halogen denoted by X

ns2np5

F- is most reactive because it is the least polarizable

iodine is the least reactive

form oxyacids with oxygen

Hypo(hal)ous acid

HOX

ox state = +1

(hal)ous acid

HOXO

+3

(hal)ic acid

HOXO2

+5

per(hal)ic acid

HOXO3

+7

Group 16 (Chalcogens)

O, S, Se, Te, Po

Oxygen

ox.states: 0 (O2), -1 (peroxides), -2 (most common)

Sulfur

S8 most common, S, S2, S6, Sn (2000-5000) also exist

many sulfur oxides (dioxide and trioxide = most common)

many sulfur oxoanions exist (common = sulfite, sulfate, and thiosulfate)

applications: skunk smell; sulfuric acid = fertilizer, wastewater processing, mineral processings; vulcanized rubber used for tires includes sulfur bonds

Group 15 (Pnictogens)

N, P, As, Sb, Bi

Group 15 properties

multiple ox. states

ns2np3

Nitrogen

N2(g) is nearly inert

prevents explosions and human overdose on O2

reactions are fast

high volume expansion

applications: propellants, DNA, nitrogen fixation processes, fertilizer, laughing gas

Phosphorus

+3, +5

white phosphorus (P4) and red P (P4-like polymer) are common allotropes of phosphorus

white P forms oxides in oxygen

some P oxides from acids in water

applications: ATP and ADP, fertilizer

Arsenic

metalloid with various allotropes

used to strengthen alloys

semiconductor

toxic and found in groundwater

applications: pesticides, herbicides, insecticides

Antimony

mined in China

applications: solders, bullets, bearings, fire retardants

Bismuth

white, silver-pink hue

highest atomic mass element that is stable

relatively low toxicity as a heavy metal and thus subs for lead

applications: Pepto-Bismol, cosmetics, pigments

Group 14 (Tetragens)

C, Si, Ge

carbon

strong bonds

cyclic and acyclic structures

bonds with itself and other atoms

forms single and multiple bonds

allotropes: graphite, diamonds, Buckminsterfullerenes, nanotubes, graphene

diamond is the hardest naturally occurring substance

highest sublimation point of all elements

Si

many oxides of silicon (silicates)

zeolites = aluminosilicates

major component of glass

silicone = oils, rubber, implants, high-temp lubricants

component of dust and sand

Germanium

chemically similar to Sn and Si

mined from sphalerite

applications: semiconductor in transistors, fiber optics, solar cells

B

• electron deficient, can have an incomplete octet

• metalloid

• covalent

• forms dimers

• forms covalently bonded allotropes

• behaves more like Si than Al

• +3 ox. state

• hard, brittle, not very reactive

• used as dopant in semiconductor industry

  • used in glassware due to resistance to thermal shock

actinides

5f series (elements 89-102)

• high density

• metallic appearance

  • variety of possible oxidation states

lanthanides

atomic numbers 57-70

• soft metals

• lustrous nature

• higher binding energy

• dissolve quickly in acid, produce lots of energy with hydrogen

representative elements

elements present in s- and p- blocks except inert gases

group

vertical column

period

horizontal row

active metals

metals that react strongly or quickly with other substances

ex. Li, Na, K, Rb, Cs (aka. alkali)