Transcript The Elements

The Elements
Representative and
Transition Elements
Section 15-1 and 15-2
Groups 1 and 2
• Always found in nature combined
with other elements
• Active metals
– Readiness to form new substances
• All metals except hydrogen
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Alkali Metals
•
•
•
•
Silvery solids
Low densities
Low melting points
Increase in reactivity as you
move from top to bottom
– Most reactive is Francium
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3
Alkali Metals
• Uses:
– Lithium—batteries
– Sodium—table salt
– Sodium and Potassium—dietary
requirements
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4
Alkali Earth Metals
• Each is denser, harder, and has
a higher melting point than the
alkali metal in same period
• Reactive, but not as reactive as
alkali metals
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Alkali Earth Metals
• Uses:
– Beryllium—found in gems emerald
and aquamarine
– Magnesium—found in chlorophyll
of green plants
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Groups 13 thru 18
• Not all solid metals
• A single group can contain
metals, nonmetals, and
metalloids
• A single group can also have
members that are solids, liquids,
and gases
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Group 13—Boron Family
• All metals except boron (brittle,
black metalloid)
• Used to make a variety of
products
– Cookware—boron
– Soft-drink cans—aluminum
– Computer chips--gallium
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Group 14—Carbon
Group
• Carbon—nonmetal
– Diamond and graphite
– Found in all living things
• Silicon & Germanium—metalloid
– Semiconductors
– Computer chips
• Tin & Lead
– Two heaviest elements in group
– Lead—x-ray aprons, car batteries
– Tin—pewter, toothpaste, coating for steel
cans
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Group 15—The Nitrogen
Group
• Nitrogen & Phosphorus
– Nonmetals
– Required by living things
– Part of DNA
• Nitrogen
– 80% of air you breathe
– Get nitrogen for body from eating plants
• Phosphorus
– White phosphorus—can’t be exposed to
air—it will explode !!
– Red phosphorus—used for head of
matches
– Also needed for healthy teeth and bones
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Group 16—the Oxygen
Family
• Oxygen
– 20% of Earth’s atmosphere
– Required for combustion
– Ozone shields organisms from radiation
• Sulfur
– Solid, yellow nonmetal
– Used to make sulfuric acid
• Paint, fertilizer, detergent, rubber
• Selenium
– Conducts electricity when exposed to
light
– Used in solar cells, photographic
materials
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Group 17—The Halogen
Group
• All metals except for astatine
(radioactive metalloid)
• Means “salt-former”
– Example, table salt—sodium
chloride
• Most reactive is fluorine
• Least reactive is iodine
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Group 18—The Noble
Gases
• Rarely combine with other elements
• Great for signs
– Each glows a different color light when electricity
is passed through
• Helium
– Less dense than air
– Great for balloons
• Argon
– Most abundant
• Krypton
– Used to illuminate landing strips
• Radon
– Radioactive; produced naturally
– Harmful; can cause lung cancer
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Transition Elements
• Groups 3-12
• All metals
• Most found combined with other
elements in ores
• Few found as pure elements
(gold and silver)
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Iron Triad
• Elements in period 4
– Iron, cobalt, nickel
• Have magnetic properties
• Industrial magnets—alloy of nickel,
cobalt, aluminum
• Nickel used in batteries
• Iron is necessary in hemoglobin to
transport oxygen in body
• Iron also combined with other metals
to produce steel
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Uses of Transition
Elements
• Tungsten—highest melting point
of any metal
– Used as filament in light bulbs
• Mercury—lowest melting point
– Used in thermometers and
barometers
– Only metal liquid at room
temperature
– Poisonous to living things
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Uses of Transition
Elements
• Chromium—comes from Greek
word for color, chroma
– Used in paints
• Platinum group
– Ruthenium, rhodium, palladium,
osmium, iridium, and platinum
– Can be used as catalysts
– Used to produce electronics
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Lanthanides
• Also called rare earth elements
• Usually found in combination with
oxygen in Earth’s crust
• Soft metals than can be cut with
a knife
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Actinides
• All radioactive
• Thorium, protactinium, uranium are
only ones found naturally on Earth
• Plutonium—used to fuel nuclear
power plants
• Americium—used in smoke detectors
• Californium-252—used to kill cancer
cells
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