Element Classes

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Element classes

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CA Standards

Students know how to use the periodic table to identify alkali metals, alkaline earth metals, transition metals, metals, semimetals (metalloids), nonmetals, halogens and noble gases.

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Alkali Metals

All alkali metals have 1 valence electron

Alkali metals are NEVER found pure in nature; they are too reactive

Reactivity of these elements increases down the group

Potassium, K reacts with water and must be stored in kerosene

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Alkaline Earth Metals

All alkaline earth metals have 2 valence electrons

Alkaline earth metals are less reactive than alkali metals

Alkaline earth metals are not found pure in nature; they are too reactive

The word “alkaline” means “basic”

common bases include salts of the metals

Ca(OH)2

Mg(OH)2

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Properties of Metals

Metals are good conductors of heat and electricity

Metals are malleable

Metals are ductile

Metals have high tensile strength

Metals have luster

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Transition Metals

Copper, Cu, is a relatively soft metal, and a very good electrical conductor.

Mercury, Hg, is the only metal that exists as a liquid at room temperature

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Properties of Metalloids

They have properties of both metals and nonmetals.

Metalloids are more brittle than metals, less brittle than most nonmetallic solids

Metalloids are semiconductors of electricity

Some metalloids possess metallic luster

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Silicon, Si – A Metalloid

Silicon has metallic luster

Silicon is brittle like a nonmetal

Silicon is a semiconductor of electricity

Other metalloids include:

Boron, B

Germanium, Ge

Arsenic, As

Antimony, Sb

Tellurium, Te

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Nonmetals

Nonmetals are poor conductors of heat and electricity

Nonmetals tend to be brittle

Many nonmetals are gases at room temperature

Carbon, the graphite in “pencil lead” is a great example of a nonmetallic element.

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