Transcript File ch 17 elements and their propertiesx

Elements and Their
Properties
Chapter 17
METALS
Chapter 17 Section 1
Metals
are located on the left
side of the periodic table and
are generally shiny, malleable,
ductile, and good conductors
Properties of Metals

Except for mercury, metals are solids at room
temperature.

Metallic luster is the shiny property of metal.

Metals are malleable, which means they can be
hammered or rolled into sheets.

Metals are ductile, which means they can be drawn into
wires.

The properties of metals make them suitable for many
uses.
Metals and the periodic table
 Most
elements are metals.
 Except for hydrogen, all the elements
in groups 1 through 12 are metals.
 The elements under the stair-step line
in groups 13 through 15 are also
metals.
Bonding in metals
– metals tend to give up
electrons easily in chemical reactions because they are not
strongly held by the protons in the nucleus.
Bonding with nonmetals


Ions are charged particles with
more or fewer electrons than
the neutral atom. Both metals
and nonmetals become more
chemically stable when they
form ions.
A metal ion and a nonmetal ion
join to create an ionic bond.
Metallic Bonding

Metallic bonding is bonding
with other metals.

Positively charged metallic ions
are surrounded by a sea of
electrons.

Because the outer-level
electrons are weakly held and
travel relatively freely, metals
are good conductors of heat
and electricity.
The Alkali Metals

Group 1 on the periodic table

Shiny, malleable, ductile and good conductors of heat and
electricity.

Softer than most other metals

The most reactive metals.

Alkali metals do not occur naturally in their elemental
forms because they are so reactive.

One electron in the outer energy level which is easily
given up with an alkali metal combines with a nonmetal.
Lithium, sodium, and
potassium
Rubidium, cesium
and francium
 We

A radioactive element
is one in which the
nucleus breaks down
and gives off particles
and energy.

Francium is
radioactive and
extremely rare.
need sodium
and potassium to
stay healthy
 Lithium
compounds
are sometimes used
to treat bipolar
disorder.
The Alkaline Earth Metals
 Group
2 of the periodic table
 Not found as free elements in nature
 Two electrons in the outer energy level
which are given up when combining
with a nonmetal.
 Some are used to color fireworks.
Colors of elements in Fireworks
Magnesium
• Magnesium’s
lightness and
strength make it a
good material for
many common
items.
• Most living things
depend on
chlorophyll, a
magnesium
containing
compound.
Calcium
• Seldom used
as a free
metal
• Calcium
compounds
are essential
for life
Other alkaline
earth metals
• Barium sulfate
is used to
diagnose
digestive
disorders
• Radium is
radioactive and
is found
associated with
uranium. It was
once used to
treat cancers.
The Transition Elements

Transition elements are in groups 3 through 12

Considered to be in transition between the main
group elements.

The main group elements are groups 1 and 2 and
groups 13 through 18.

Transition elements often form colored
compounds (i.e. gems, colored glass)
Iron, cobalt and
nickel
Copper, silver and Zinc, cadmium, and
gold
mercury
• Sometimes called the
iron triad
• The most common
magnetic elements
• Used in steel and
other metal mixtures
• Iron is the 2nd most
abundant metal in
Earth’s crust and the
most widely used of
all metals.
• Nickel is also used to
give a shiny
protective coating to
other metals.
• Found as free
• Group 12
elements in nature
• Zinc and cadmium
• Known as the coinage
are often used to
metals
coat metals such
• The US stopped
as iron.
making coins with
gold in 1933 and with • Mercury is the
silver in 1964 due to
only metal that is
the expense.
a liquid at room
• Used in medals,
temperature
electrical wiring, film
and photo paper, and
jewelry.
The Inner Transition Elements –
disconnected from the rest of the periodic table
The lanthanides
 Numbers
 Called
58 to 71
the
lanthanide series
because they follow
the element
lanthanum
The actinides

Numbers 90 to 103

Called the actinide series
because they follow the element
actinium

They are unstable.

Rare or nonexistent in nature

Thorium and uranium are the
only actinides found in the
Earth’s crust in usable quantities.
Metals in Earth’s Crust

Earth’s hardened outer layer is called the crust.

Metals that are found in Earth’s crust are minerals.

Ores are mixtures of minerals, clay, and rock that occur naturally in Earth’s
crust.

Most metals must be mined and separated from their ores.

Metal that has been refined into pure form can later be alloyed with other
metals.

Mining is expensive. If the cost of removing the waste rock becomes greater
than the value of the desired material, the mineral mixture is no longer
classified as an ore.

Chromium is important because it is used to harden steel.
Nonmetals
Chapter 17 Section 2
Nonmetals are located on the
right side of the periodic table
and are generally dull, brittle,
and poor conductors.
Properties of Nonmetals

Usually gases or solids at room temperature.

Solid nonmetals are not malleable or ductile.

Solid nonmetals are powdery or brittle.

Poor conductors of heat and electricity (i.e. air)

Electrons are not as free to move as in metals.
Nonmetals and the periodic table

All, except hydrogen, are found to the right of the
stair-step line.

Noble gases (group 18) are the only group of
elements that are all nonmetals.

Group 17 elements are called the halogens. All
halogens, except astatine, are nonmetals.

Other nonmetals are found in groups 13 – 16.
Bonding in nonmetals
 Nonmetals
become negative ions when
they gain electrons from metals. (ionic
bonding)
 Nonmetals bonding with other
nonmetals usually share electrons and
form covalent bonds.
Hydrogen
 About
90% of all atoms in the universe are
hydrogen atoms.
 Most hydrogen on Earth is found in water.
 Hydrogen forms a diatomic molecule (two
atoms of the same element in a covalent
bond).
 Highly reactive!
The Halogens
Group 17 on the periodic table.
 Very reactive.
 Compounds have many uses.
 When a halogen gains an electron from a metal, an ionic
compound called salt is formed (i.e. NaCl).
 In gaseous state, halogens form reactive diatomic molecules and
can be identified by distinctive colors.


Chlorine – greenish-yellow

Bromine – reddish-orange

Iodine - violet
Flourine
Chlorine and
Bromine
• Most chemically • Chlorine is the
active of the
most abundant
nonmetals
halogen
• Many uses (i.e. • Obtained from
fluoride,
seawater
etching glass,
• Bromine is the
frosting inside
only nonmetal
of lightbulbs)
that is a liquid
• Used to create
at room
semiconductors
temperature.
• Also obtained
from seawater.
Iodine and
Astatine
• Iodine is obtained
from seawater.
• Essential for
production of
thyroxin hormone –
prevents goiter
• Astatine is
radioactive and
rare.
• Astatine is being
investigated as a
possible treatment
for cancer.
The Noble Gases

Exist as isolated atoms.

Stable because their outermost energy levels are full.

Helium is less dense than air, but does not burn in oxygen.
This makes it useful for blimps and balloons.

Electrical current will cause the noble gases to glow.
Some are used in brightly colored signs (i.e. neon and
argon).

Helium neon lasers produce beams of intense, red light.
Mixed Groups
Chapter 17 Section 3
Some groups on the periodic
table contain metalloids –
elements that have some
properties of metals and some
properties of nonmetals.
Properties of Metalloids
 Metalloids
are elements that have some
properties of metals and some properties of
nonmetals.
 Metalloids
can form ionic bonds and
covalent bonds.
 Groups
13 – 17 are mixed groups and
contain metals, nonmetals, and metalloids.
The Boron Group

Boron is the first element in group 13. It is a
metalloid.

Aluminum is the most abundant metal in Earth’s
crust.

Gallium is a metal used in electronic components.

Boron is the only metalloid in group 13. All other
elements are metals.
The Carbon Group – each element in the carbon
family has 4 electrons in its outer energy level.
Carbon
• Nonmetal
• Occurs as an
element in coal
and as a
compound in oil,
natural gas and
foods.
• All organic
compounds
contain carbon.
Allotropes of
Carbon
Graphite and
Diamond
• Allotropes are
different
molecular
structure of the
same element
(i.e. graphite and
diamond,
buckyballs)
• Graphite is an
excellent
lubricant
• Diamond is
transparent and
extremely hard
Buckyballs
• Discovered in the
mid 1980s.
• Soccer-ballshaped
• Used to
synthesize
nanotubes.
• Tens of thousands
of nanotubes
could be stacked
to get the
thickness of one
sheet of paper.
Silicon and germanium

Silicon is a metalloid. Second only to oxygen in
abundance in Earth’s crust.

Silicon is found in sand and almost all rocks and soils.

Silicon has two allotropes.

Main conductor of semiconductors.

Germanium is the second metalloid in group 14.

Also used in semiconductors.
Tin and Lead
 Tin
is a metal used to coat other metals.
 Tin
also combines with other metals to
make bronze and pewter.
 Lead
 No
was once widely used in paint.
longer used – highly toxic.
 Used
in car batteries.
The Nitrogen Group –
makes up group 15. Each
element has 5 electrons in its outer energy level. Form covalent
compounds with other nonmetallic elements.
Arsenic, antimony, and
bismuth
Nitrogen and Phosphorous

Nitrogen is a nonmetal.

Arsenic is a metalloid.

Nitrogen is the fourth most abundant
element in your body.

Antimony is a metalloid.

Forms diatomic molecules.

Bismuth is a metal.

Antimony and Bismuth are used
with other metals to lower their
melting points.

Bismuth is used in automatic firesprinkler heads.

Arsenic compounds are toxic.

Phosphorous is a nonmetal.

3 allotropes

Used for many things (i.e. water
softeners, fertilizers, match heads
and fine china)
The Oxygen Group – group 16
Oxygen

Sulfur is a nonmetal that has several
allotropes.

Sulfur combines with metals to form
sulfides that are used as pigments in
paints.
Living things require O2 for
respiration.

During electrical storms some
oxygen molecules change into
ozone molecules (O3).
Selenium (nonmetal) is needed in
trace amounts in your diet. Toxic if
too much gets into your system.

Tellurium and polonium are
metalloids in group 16.

Nonmetal

Exists in the air as diatomic
molecules.


Other Group 16 Elements
Discovering and Making Elements
 The
first elements known were those
that occur naturally in their elemental
forms (i.e. gold, lead, tin and carbon).
 Most elements were discovered after
the birth of modern chemistry in the
1700s.
Synthetic elements

By 1935 only 4 elements with less than 92 protons were missing from the periodic
table.

Elements created in the lab are called synthetic elements. They are created by
smashing existing elements with particles accelerated in a heavy ion accelerator.

Why make elements?
•


used in nuclear reactors and for medical purposes.
Transuranium elements?
•
Have more than 92 protons.
•
Found toward the bottom of the periodic table.
•
ALL of the transuranium elements are synthetic and radioactive.
Seeking Stability
•
By studying how the synthesized elements form and disintegrate, scientists can gain an
understanding of the forces holding the nucleus together.