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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 valence 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 (ductile) and shaped (malleable) • 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 – http://www.youtube.com/watch?v=QSZ-3wScePM – Braniac http://www.youtube.com/watch?v=m55kgyApY rY – 1 valence electron (+1 ion) • Group 2: Alkaline Earth Metals – Less reactive than alkali metals – 2 valence electrons (+2 ion) – http://www.youtube.com/watch?v=8GOPQVsbiGk • 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) – http://www.youtube.com/watch?v=u2ogMUDBa 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. O2)