Descriptive Chemistry

CHE 2C Descriptive Chemistry by Samantha Hugo
Noble Gases: odorless, colorless, and monoatomic. Their filled electron shell makes
them rather unreactive. Low mp, low bp, low interatomic forces. At STP, they are
nearly ideal gasses.
Monoatomic, almost make no compounds
Inert, ox state = 0
- Escapes atmosphere but found trapped in some places (Texas)
- Used to dilute gases for safety
- No viscosity
- Multiple liquid phases
- Odorless, colorless
- Emits light under currents
- Third most common gas in the air
- Inert gas for welding
- In some light bulbs
- Radioactive dating (Ar-K)
Hcp packing structure
Product of fission
Used to measure the worldwide nuclear activity
Easier to oxidize than the other noble gasses
In halogen Lamps
In flash tubes
Found in some hot springs
Could be connected to lung cancer
Product of radioactive processes deep in the earth
NG are not completely inert, compounds with noble gasses can form under specific
- Needs a readily ionizeable noble gas atom. Larger NG, more likely it will form
compounds (Xe is the best, Rn is too radioactive to form stable compounds)
High EN to bond with NG (O or F are good)
Halogens are referred to as X. Produced industrially through electrolysis or
oxidation. Electron configuration = ns2np5. F is the most reactive because it
is the most polarizable. I is the least.
F is most reactive, At is the least
Activity Series: More reactivity can replace less reactive in solution
F2 is the best ox agent
HF is etch glass
Colorless, corrosive, nonmetal
Found in nature
Combined with metals or as pure elements (diatomic)
Astatine is not of practical importance because it short lived and radioactive.
Halogens form with oxygen to form oxy acids
HOX is hypohalous acid
HOXO is halous acid
HOXO2 is halic acid
HOXO3 is perhalic acid
Group 16: Chalcogens
O2 and O3 are elemental forms. O3 (ozone) protects from the energy (hv) of harmful
UV rays. Energy produced is transferred to N2 in the atmosphere in the form of
kinetic energy.
Common oxidation states of oxygen are O: O2, +1: peroxides (O22- anion), and +2:
most common.
Oxygen has two common allotropes O2 (oxygen) and O3 (ozone)
Sulfur has many elemental forms, S8 is the most common. The smell of skunks is
because of sulfur. Sulfuric acid is used as a fertilizer, wasterwater processing, and
mineral processing. Vulcanized rubber used for tires have sulfur bonds. Sulfur is
used in hair care products because hair contains S-S bonds.
Polymorphs: same bonds, different crystal structures
Selenium and Tellurium applications: semiconductors, alloys, glass coloring.
Polonium is radioactive. Simple cubic packing structure. Po is in tobacco and may be
tied to cancer. Very lethal.
Group 15: Pnictogens
Exist in multiple oxidation states. Ns2np3
N is either extremely stable or extremely reactive.
N2(g) is nearly inert. Used as inert atmosphere for water and oxygen sensitive
materials. In air, it prevents explosions by reactions with O2(g) by acting as a
diluent. Prevents humans from ODing on O2(g)
Nitroglycerin and TNT are nitrogen containing explosives. Exothermic, stable
products, fast, and high volume expansion. DNAand nitrogen fixation processes
contain nitrogen. NH3 is a fertilizer. N2O is laughing gas and a propellant for
whipping cream.
+3 and +5 ox states
P5 and P2O5 are common compounds
Biological compounds: ATP and ADP
- Metalloid with various allotropes
- Used to strengthen alloys
- Semiconductor
- Toxic and notoriously in groundwater
- Pesticides, herbicides, and insecticides
- Mined in China
- Solders, bullets, bearings, fire retardants
- White, silver/ pink hue
- Highest atomic mass element that is stable
- Low toxicity as a heavy metal, therefore can substitute for lead
- Pepto-Bismol, cosmetics, pigments
Group 14: Tetragens
- Forms strong bonds
- Cyclic and Acyclic structures
- Bond with itself and other atoms
- Single and multiple bonds
- Allotropes are graphite and diamonds, Buckminster Fullerenes, Nanotubes,
and Graphene.
- Diamonds are hardest naturally occurring substance
- Highest sublimation points of all elements
Graphene: one atom thick sheet of carbon
Can form double, triple, ring, chain, and branched chain bonds
Diamond is a pure carbon, Crystalline (single molecule), covalent molecules,
tetrahedral, high mp, brittle
- Buckyballs= fullerenes. Spherical carbon
- Nanotubes (carbon fiber): long tubes of individual molecules
- In glass
- Oils, rubber, implants, and high temp lubricants
- Components of dust and sand
- Similar to Sn and Si
- Mined from Sphalerite
- Semiconductor in transistors, fiber optics, and solar cells
Group 13:
Boron is electron deficient, incomplete octet. Metalloid/ could be nonmetal.
Covalent bonds, but numeroud analogues with transition metals in structure and
cluster chemistry.
Form dimmers, covalently bonded allotropes, like carbon. Form clusters with 5-12 B
atoms. Behaves more like Si than Al. +3 is most common ox state. Hard, brittle, and
unreactive. Used as a dopant in the semiconductor industry. Resists to thermal
shock .
- All possess +1/+3 oxidation states.
- High charge density, high polarizing power, covalent bonds
- Ns2np1
- All can possess +3 ox state, all but B and Al can be +1
8.3% of earth’s crust
light alloys
good in industry
Chapter 22
Group 1 has the biggest atomic radius, easiest to ionize (lowest IE). Low
First member is the lightest and has different features than the rest of the
Cations are smaller, anions are larger.
Polarizing power is related to charge density (p): charge/ unit volume
Increase in charge density, increase in polarizing power (greater ability to
distort electron cloud of an anion towards itself)
Alkali Metals:
 Mostly water soluble, very active
 Big atomic radii= low density, float on H2O.
 Weak metallic bonding
 Soft metals, low MP
 All good reducing agents (good at oxidizing)
 Very reactive
 Ns1
 Produce H2 with water
 Can make several compounds with oxygen
 Shiny soft metals with low mps
 Not found in nature as free elements
 Very reactive
 Form alkaline solution in water
Alkaline Earth Metals:
 Slightly soluble in water.
 Basic, alkaline
 More metallic than group 1
 Form mostly ionic compounds
 Decrease ionic size, increase ionic charge
 Ns2, easy to lose
 Reactive
 Good reducing agent
 All but Be forms hydroxides because Be is a semimetal
 Lusterous, silvery metals
 Reactive
 Not found in nature as free elements