Transcript Chemical Groups & Families

Chemical
Groups and
Families
Group 1-Alkali Metals
Li
Na
 shiny solids, malleable, ductile
 good conductors of electricity
 low densities, low melting points
K
 soft enough to be cut with a knife
Rb
 reacts readily with air and water
 intense chemical reactivity
Cs
 reactivity increases as you go down the
group
Fr
 Na and K most abundant of family (rank
7th and 8th by mass in earth’s crust)
 Never found as free elements in nature
Called “Alkali” because they
form basic solutions when react
with water
Na + H2O
NaOH + H2
Group 2-Alkali Earth
Metals
Be
Mg
Ca
Sr
Ba
Ra
 higher densities and melting points
than group 1
 also form basic solutions with water
 almost as reactive as group 1
 Ca, Sr, Ba and Ra react w/water
 also not found in nature in elemental
state
 Ca & Mg most abundant of family (rank
5th and 6th by mass in earth’s crust)
 Be differs from others: very high
melting point and as strong as steel
Transition Metals
Transition Metals as a Group
 Play an important role in living
organisms; Co found in vitamin B12, Fe is
an essential part of hemoglobin
 Many also valuable as strong,
structurally useful materials; Fe primary
building material, Cr protective coating
on metals, Ag and Au used for coins and
jewelry
 Vary greatly in abundance; Fe and Ti
rank 4th an 10th by mass in Earth’s crust.
Pt and Ir are very rare
Transition Metals as a Group
 Properties vary from family to family
 Most have high densities (this is why
they are called the “heavy metals”)
 Most have high melting points
 Most are good conductors of electricity
 Most are malleable
Many form more than one ion
BRITTLE
DUCTLE
LOW MELTING PTS
Inner Transition Metals
Lanthanides
 Elements of the 4f series
 Very similar to one another because they all
have the same number of valence electrons
 All readily form 3+ ions (ALL considered part of
group 3)
 Soft, silvery metals
 Only somewhat less reactive than group 2
 React with air and slowly with water
 Widely distributed in nature, but generally
occur together; hard to separate
 Little commercial importance
Lanthanides
 Europium is used in television tubes to
produce the red color
Lanthanium used in studio carbon arc
lighting and projection lenses in movie
industry
Cerium-catalyst used in self cleaning
ovens
Ytterbium used to strengthen stainless
steel knifes
Promethium used as a nuclear powered
battery
Actinides
 Elements of the 5f series
 All Isotopes of these elements are
RADIOACTIVE
 Only Th and U occur in nature
 All others are artificial, produced by
nuclear bombardment reactions
Plutonium salts used for coloring glass
and enamels
Americium used in smoke alarms
Uranium nitrate compound used in
photographic toners
BORON Group
B
Al
Ga
 All form 3+ ions
 Al is most important; 3rd most abundant
element in Earth’s crust
 Most Al occurs in ores and compounds
in nature; has to be extracted
In
 Al has low density, but when alloyed
with other metals is quite strong and does
not corrode
Tl
 Many commercial uses
 Boron used for heat resistant glass and
eye disinfectant
 Ga used in cell phones
Bauxite: Aluminum ore
NITROGEN Group
N
 N and P are non-metal; As and SB are
semi-metals and Bi is a metal
P
 N makes up approx 80% earth’s
atmosphere
As
Sb
Bi
 N a gas at STP
 P compounds with O very important;
phosphoric acid
 As used shotgun pellets and metal
mirrors
 Sb used as a solder and ceramic glazes
 Bi used as an antacid
CARBON Group
C
 Carbon is a non-metal; Si and Ge are
semi-metals and Sn and Pb are metals
Si
 Carbon widely distributed throughout
the Earth’s crust
Ge
 Compounds of C and H are called
hydrocarbons; fuels
Sn
 Compounds of C called “organic”
Pb
 CO2 byproduct of human respiration and
necessary for plant growth
 Si 2nd most abundant element in Earth’s
crust; sand
 Si also major component of sand
CARBON Group (con’t)
C
Si
Ge
Sn
Pb
 Si and Ge are semi-metals; semiconductors; used to make transistors,
solar cells and computer chips
 Sn and Pb very common and used for
hundreds of years
 Sn used to coat steel cans
 Pb used in pipes and car batteries
 Compounds containing lead ions have
been linked to cancer, so not used as
much any more
OXYGEN GROUP
O
 Oxygen most abundant element on
earth
S
The largest source of elemental oxygen
is atmosphere
Se
Oxygen also found in compounds called
oxides
Te
Elemental oxygen exists as both O2 and
O3 (ozone). Ozone has strong, irritating
odor and is considered a pollutant. It
attacks structural materials and
plant/animal tissue.
Po
Ozone absorbs high energy UV radiation
from sun
OXYGEN GROUP
O
 Sulfur occurs pure in nature-known as
brimstone
S
Also occurs in compounds such as FeS2
known as “fools gold”
Se
Many sulfur compounds have unpleasant
odor. Sulfur compound added to natural
gas to detect leaks
Te
Po
Largest use of sulfur is production of
Sulfuric acid. Sulfuric acid has many
uses, most commonly lead storage
batteries
Selenium copies used in photocopiers
Polonium used in radioactive power
Halogens
F
Cl
Br
I
At
 Name Halogen comes from Greek for
“Salt Former”; reaction of most metals
with halogens form salts
 Highly reactive with metals and most
non metals
 Do not occur as free elements in nature
 F very corrosive gas; most reactive of
all non-metals
 Cl most industrially used
 At is very rare; all isotopes are
radioactive
NOBLE GASES
He
Ne
Mostly non-reactive
 Ar most abundant; 1% of Earth’s
atmosphere
Ar
 Discovered after many of other
elements because they do not form
compounds
Kr
 Some Xe compounds have been formed,
but they are not very stable
Xe
Rn
HYDROGEN
H
 Typically shown listed with Group 1 but
actually a non-metal, colorless, odorless
gas
So light it escapes the gravitational pull
of the earth, so rare in atmosphere
Most of Earth’s hydrogen found
combined with oxygen in water
Also frequently combined with carbon.
Hyrocarbons-class of compounds
containing hydrogen and carbon. All fuels
are hydrocarbon (coal, petroleum, natural
gas) as well as plants and animals. (Term
“Fossil Fuels” refers to petroleum that is
broken down dinosaurs)
H
 9th most abundant element on Earth’s
surface. (Crust, water, atmosphere)
Most abundant element in universe
Elemental hydrogen obtained
commercially from hydrocarbons
Largest commercial use is in
manufacture of ammonia (NH3) which is
used in fertilizers
Also used to prepare organic
compounds like Methanol and Ethanol.
Methanol is used as a fuel in race cars.
Ethanol is currently used as a fuel in
some corn producing states.
Currently investigating using H fuel cells
to power cars