Elements and Their
Properties
What Makes an Element Reactive?
• An incomplete valence electron level.
• All atoms (except hydrogen & helium) want to
have 8 electrons in their very outermost energy
level (This is called the rule of octet.)
• Atoms bond until this level is complete. Atoms
with few valence electrons tend to lose them
during bonding.
•Atoms with 5, 6 or 7 valence electrons tend to
gain electrons during bonding.
Metals
• Metal: Elements are usually solids at room
temperature.
• Mercury is an exception.
• They are good conductors of heat and
electricity.
• They have luster (reflect light).
• Metals are malleable, meaning they can be
hammered and rolled into sheets.
• Metals are ductile, meaning they can be
drawn into wire.
• Most elements are metals.
Ionic Bonding in Metals
• Atoms of metals usually have one to three
electrons in their valence shell.
• Because of this, they tend to give valence
electrons away when bonding with a
nonmetal.
•This forms an ionic bond.
•This makes them both stable.
Metallic Bonding in Metals
• Metallic bonding is not ionic, because no
electrons are given, taken, or even shared (a
covalent bond).
• The valence electrons flow freely among the
positively charged nuclei and form a cloud
around the ions of the metal.
• Metals are good conductors of electricity
because the valence electrons are weakly
held.
• http://www.drkstreet.com/resources/metallic-bondinganimation.swf
Alkali Metals
•The alkali family is found
in the first column of the
periodic table.
•Atoms of the alkali
metals have a single
electron in their
outermost energy level,
in other words, 1 valence
electron.
•They are shiny, have the
consistency of clay, and
are easily cut with a
knife.
Alkali Metals
•They are the most
reactive metals.
•They react violently with
water.
•Alkali metals are never
found as free elements in
nature. They are always
bonded with another
element.
•http://www.youtube.com/watch?v=YvSkXd_VVYk&NR
=1&feature=fvwp
Uses of Alkali Metals
Alkali metals and their compounds are necessary
for living things to stay healthy.
• Potassium and sodium compounds are
necessary for the nervous system and muscular
system to function correctly.
• Lithium is sometimes used to treat imbalances in
the brain.
• Rubidium and Cesium compounds are used in
photocells.
Radioactive
• Francium, the last element of the alkali metals is
rare and radioactive.
• A radioactive element is one in which the nucleus
breaks down and give off particles and energy.
• Francium is so rare that only 25 to 30 grams of it
are in Earth’s crust at a time (within uranium
minerals.
• It has never been isolated as the pure element.
• As it is so radioactive, any amount formed
would decompose to other elements.
Alkaline Earth Metals
• Alkaline earth metals are
the second column on the
periodic table (Group 2)
• They are reactive metals
that are always combined
with nonmetals in nature.
• Several of these elements
are important mineral
nutrients (such as Mg and
Ca).
• Many are used in the
production of fireworks.
Alkaline Earth Metals in Your Body
• Calcium phosphate is necessary for healthy
bones.
• Barium sulfate is used as a tracer for finding
problems in the digestive tract because it
absorbs x-rays so well.
• Radium is found with uranium and was once
used as a radioactive treatment for cancer.
Transition Metals
• Elements in groups
3-12
• Less reactive, harder
metals
• Includes metals used in
jewelry and construction
• Metals in this family are
used as metals.
Transition Metals
• The compounds of
transition metals are usually
brightly colored and are
often used to color paints.
• Transition elements have 1
or 2 valence electrons,
which they lose when they
form bonds with other
atoms. Some transition
elements can lose electrons
in their next-to-outermost
level.
Transition Metals
• Transition elements have
properties similar to one
another and to other
metals, but their
properties do not fit in
with those of any other
family.
• Many transition metals
combine chemically with
oxygen to form
compounds called oxides.
Iron oxide—rust—on iron
Iron, Cobalt, Nickel
• The three are called
the iron triad because
they are used to
make steel and other
metal alloys.
• Iron is the most
widely-used metal.
• Nickel is added for
strength and as
plating for shine.
• Cobalt added to glass
or glaze gives it a
blue color.
Copper, Silver, Gold
• In Group 11
• They are stable, very malleable, and can be found
in their purest form in nature.
• Used in the past as coin metals—too expensive
now.
• Most coins are now copper and nickel alloys
(mixtures of metals).
• Copper used for wiring due to its ability to conduct.
• Silver compounds were once used to help develop
photographs (before the digital age).
• Silver and gold are used in jewelry due to their
beauty, resistance to corrosion, and relative rarity.
Copper, Silver, Gold
Zinc, Cadmium, Mercury
• In Group 12
• Zinc and cadmium are often used as plating materials
(coating) over other metals because they have protective
qualities.
• Cadmium is used in rechargeable batteries.
• Mercury is used in thermometers, thermostats, batteries,
and CFL bulbs.
• They are all toxic.
– Mercury is also a bi-product of coal burning and other
industry. The sludge can leach into groundwater.
Mercury poisoning can lead to neurological damage
and death.
– While zinc is a necessary element for the body, too
much is dangerous.
Zinc, Cadmium, Mercury
How a mercury thermostat works
Rare Earth Elements
• The thirty rare earth
elements make up the
lanthanide (row 1) and
actinide (row 2) series.
• One element of the
lanthanide series and most
of the elements in the
actinide series are called
trans-uranium, which
means synthetic or manmade.
• Magnets made from rare
earth elements are some of
the strongest.
Rare Earths: Lanthanides
• Atomic numbers 58 – 71
• La, Ce, Pr, and Sm bonded with carbon are
used in the motion picture industry
for making special lenses and
lamps.
• Eu, Gd, and Tb are used in nuclear reactors
and also to produce the colors in televisions
when an electron beam hits them.
Rare Earths: Actinides
• Atomic numbers 90 103
• All are radioactive and
unstable
• Difficult to study
• Thorium is used to
make high-quality,
distortion-free camera
lenses.
• Uranium is used in
nuclear reactors and in
nuclear weapons.
• Uranium glass glows
under black light.
METALS IN THE CRUST
• Many of the metals we use are found in
ores within Earth’s crust.
• To separate a metal from other elements,
chemicals and heat must be added.
• Adding heat is called roasting.
• Chemicals and heat together are called
smelting.
• The process of mining and smelting is quite
expensive.
• Google Earth
Nonmetals
• Nonmetals :
1. are elements that usually are gases or
brittle solids at room temperature.
2. do not usually conduct heat or electricity
well.
3. are generally dull in luster.
4. are found in the upper right hand corner
of the periodic table, plus hydrogen.
Bonding in Nonmetals
• Electrons in nonmetals are strongly
attracted to the nucleus.
• Because of this, the electrons don’t move
away as easily, so they don’t conduct
electricity well.
• They can form both ionic bonds—where
electrons are given or taken—or covalent
bonds—where electrons are shared
between atoms.
• When nonmetals bond with a metal, ionic
bonds are formed.
• When nonmetals bond with other
nonmetals, covalent bonds are formed.
• Hydrogen belongs to a
Hydrogen family of its own.
• Hydrogen is a diatomic,
reactive gas. Two atoms of
it H bond together in
nature.
• Hydrogen was involved in
the explosion of the
Hindenberg. It is very
reactive—group 1.
• Hydrogen is promising as
an alternative fuel source
for automobiles
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wp
Hydrogen
• Hydrogen can gain an electron when it
bonds with an alkali metal or an alkaline
earth metal to form hydrides.
• Hydrogen only needs 2 electrons to fill up
its single valence shell, so, technically, it
can’t reach the “rule of octet.”
• Halogens are in group
17 and have 7 valence
electrons, which
explains why they are
the most active nonmetals. Always found
combined with other
elements in nature.
• They are very reactive
diatomic nonmetals.
Halogens
Halogens
• Halogen atoms only need to gain 1 electron
to fill their outermost energy level.
• They react with alkali metals to form salts.
• Fluorine is the most reactive element of all
elements.
• It is used in compounds to:
• prevent cavities
• etch glass
• It was once used in a compound with
carbon (fluorocarbon) in refrigeration and
as a propellant in aerosol cans, but it was
found to damage the ozone layer.
Halogens
• Chlorine, the most abundant
halogen, is extracted from
seawater.
• Used as a disinfectant—
bleach.
• Bromine is the only nonmetal
that is liquid at room
temperature and is also
extracted from seawater.
• Used as a disinfectant
• Bromine compounds are used
as cosmetic dyes.
Halogens
• Iodine is solid, shiny, and purple and vaporizes
when heated—sublimation.
• Iodine is necessary for producing thyroxin in the
body and helps keep the thyroid gland healthy.
• Astatine is radioactive with no known uses
(because it’s rare).
Noble Gases
• Noble gases exist by themselves in nature
due to their valence level meeting the rule of
octet without bonding.
• They can be forced to bond with other
elements in a laboratory.
• Helium is a stable gas.
• Used in blimps and balloons
• Used in certain welding applications
generally where the metals welded are not
iron.
• Neon and argon are used in “neon” signs.
• Argon and krypton are used in electric light
bulbs to produce light in lasers.
Section 3: Mixed Groups
Metalloids
• Groups 13 through 16 have some metals, some
metalloids, and some nonmetals—often within
one family.
• A metalloid is a type of matter that can have
metallic and nonmetallic properties.
• They can form ionic or covalent bonds.
• They can conduct electricity better than
nonmetals, but not as well as some metals.
• Except for aluminum, they touch the zigzag
line on the periodic table.
Boron Family
• Elements in group 13
have 3 valence electrons.
• Includes metals and one
metalloid—Boron.
• Aluminum, the most
abundant metal in Earth’s
crust, was once
considered rare and
expensive-- not a
“disposable metal.”
Carbon Family
• Elements
in group
14 a
have 4
• This family
includes
valence
electrons.
non-metal
(carbon),
• Contains
elements
important
metalloids,
and metals.
to
life--andhas
computers.
• Carbon
many
forms, some
which
• Carbon
is theofbasis
forare
an
•Radioactive
entire
branch of chemistry
•Diamond
(organic
chemistry).
•Graphite
• Silicon
and Germanium are
•Buckminsterfullerene
important
semiconductors
used in computer chips.
• Semiconductors will conduct
electricity under certain
conditions.
Carbon Family•
Silicon dioxide is found in
Earth’s crust—in sand and
rocks.
• Its structure is crystal, similar to
a diamond.
• Silicon, a metalloid, occurs as
2 allotropes.
– An allotrope are different
forms of the same element,
where the atoms arrange in
different ways.
– Silicon can occur as a hard,
gray substance or a brown
powder.
Carbon Family
• Tin is used to coat other metals (tin cans) and
in alloys, like bronze.
• Germanium, the other metalloid in the carbon
family, is used with silicon in making
semiconductors.
Carbon Is Amazing!
• Carbon has several
allotropes, including:
–
–
–
–
Graphite
Diamond
Buckminsterfullerine
Nanotubes
• What makes an
allotrope an allotrope
is how the atoms of
an element come
together as a larger
mass.
Carbon Family
Ant (carbon-based
organism) holding
microchip (probably
made of germanium or
silicon)
Nitrogen Family •
Elements in group 15
have
5
valence
electrons.
• Antimony, a metalloid, and
• They tend
to share
bismuth,
a metal
are able to
electrons
whenpoint
they of
bond.
lower
the melting
other
metals.
• This
family includes non• Bismuth
is metalloids,
used in fire-and
metals,
sprinkler
metals.heads because of
this.
• Nitrogen makes up over
75% of the atmosphere.
• Nitrogen and phosphorus
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are both important in living
xuU&feature=related
things.
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j0A
• The red stuff on the tip of
matches is phosphorus.
Oxygen Family
• Elements in group 16 have
6 valence electrons.
• Oxygen, as O2, is necessary for
respiration, and O3 helps protect Earth from radiation.
• Many things that stink,
contain sulfur (rotten eggs,
garlic, skunks, etc.).
• Most elements in this family
share electrons when forming compounds.
• Oxygen is the most abundant element in the earth’s
crust. It is extremely active and combines with almost
all elements.
• Selenium is needed by
the body’s immune
system in small
amounts. It is also used
in photocopiers due to
its conductive
properties, and in solar
cells.
• Selenium is used as a
key ingredient in some
dandruff shampoos.
Oxygen Family
Synthetic Elements
• New elements have been made by humans.
• They are made by bombarding existing elements
with particles that have been accelerated at high
rates of speed in a particle accelerator.
– Uranium is bombarded with neutrons to make
neptunium.
– Neptunium disintegrates into synthetic
plutonium.
– Plutonium can be synthesized into americium.
– Americium is used in smoke detectors.
Synthetic Elements
• Making elements is expensive, however, the
value of them in medicine and other applications
often offsets the cost.
• In 1999, element 114 was discovered and held
together for 30 seconds—which is a long time for
most synthetic elements!
• Plutonium and 9 other “synthetic” elements have
since been found naturally in very small amounts
on Earth. All, except francium, were synthesized
before they were found in nature!
• Technically then, elements 1-98 are naturally
occurring.
Transuranium Elements
• Elements having more than 92 protons (more
than uranium) are called transuranium
elements.
• All of them are unstable, and many of them
disintegrate (decay) quickly into other elements.
This means they are all radioactive.