Atoms’ families Remember that columns are groups or families They have similar properties (e.g reactivity, density, etc.) because they have the same arrangement of valance electrons Three big groups… metals, nonmetals and metalloids (semiconductors)

Metals To the left of the stair-step Tend to give away electrons and form positive ions Good conductors of heat and electricity Can be stretched and shaped Most are solids (1 liquid) U stream: Physical Science Series: Atomic Structure and the Periodic Table

Nonmetals To the right of the stair step line Tend to gain electrons and form negative ions Poor conductors of heat and electricity (good insulators) Are brittle…can’t be shaped Mix of solids and gases (1 liquid) U stream: Physical Science Series: Atomic Structure and the Periodic Table

Metalloids Between the other two on table, touch the stair-step line Also called semiconductors Mixture of properties U stream: Physical Science Series: Atomic Structure and the Periodic Table

Families have names, too Group 1: Alkali metals –Soft, shiny –React violently with water – –Braniac # –1 valence electron (+1 ion) Group 2: Alkaline Earth Metals –Less reactive than alkali metals –2 valence electrons (+2 ion) – Transition metals –Groups 3 – 12 –Have multiple ions (+1, +2, +3, +4)

Families have names, too Group 17: Halogens –Very reactive –7 valence electrons (-1 ion) – f4 Group 18: Noble gases –Don’t react at all –No charge! Outer energy level is full. –Exist as single atoms, e.g. Ar or He (others exist as compounds, because they react with their elements, e.g. O 2 )