Periodic Table Families (IB Chem HL1 Unit 6)

Group

elements with the same number of valence electrons and therefore similar chemical and physical properties; vertical column of elements (“family”)

Period

elements with the same outer shell; horizontal row of elements

Periodicity

regular variations (or patterns) of properties with increasing atomic weight. Both chemical and physical properties vary in a periodic (repeating pattern) across a period.

Periodic Groups

• alkali metals

• alkaline earth metals

• transition metals

• halogens

• noble gases

• lanthanides

• actinides

Alkali Metals

• group 1 on the periodic table

• called alkali metals because the all react with water to form an alkali solution of the metal hydroxide and hydrogen gas

• react by losing outer electron to form the metal ion

• good reducing agents (because they can readily lose an electron)

Alkaline Earth Metals

• group 2 on the periodic table

• abundant metals in the earth (Ca and Mg especially)

• not as reactive as alkali metals

• higher density and melting point than alkali metals

Transition Metals

• variable valency and oxidation state

• forms colored compounds

• forms complex ions

• catalytic behavior

Halogens

• group group 7 on the periodic table

• react by gaining one electron to form halide ion

• good oxidizing agents (because they readily gain an electron)

Noble Gases

• group 0 (or 8) on the periodic table

• sometimes called rare gases or inert gases

• relatively nonreactive (inert)

• gases at room temperature

Lanthanides

• part of the “inner transition metals”

• soft silvery metals

• tarnish readily in air

• react slowly with water

• difficult to separate because all have two effective valence electrons

Actinides

• radioactive elements

• part of the “inner transition metals”