Ch. 3: “Atoms & the Periodic Table”

Ch. 3: “Atoms & the Periodic Table” Section 3: “Families of Elements”

1. Classify the following based on their position on the periodic table. a. Fe • transition metal b. K • alkali metal c. Sr • alkaline-earth metal d. Pt • transition metal

2. Predict whether cesium forms Cs+ or Cs2+ ions. • Cesium is an alkali metal, so it has one valence electron that is removed to form a Cs+ ion.

3. Describe why chemists might sometimes store reactive chemicals in argon, Ar. To which family does argon belong? • Reactive chemicals might react with oxygen or water vapor in the air. They will not react with argon because it is inert. • Argon is a noble gas.

4. Determine whether the following substances are likely to be metals or nonmetals: a. a shiny substance used to make flexible bed springs • metal b. a yellow powder from underground mines • nonmetal c. a gas that does not react • nonmetal d. a conducting material used within flexible wires • metal

5. Describe why atoms of bromine, Br, are so reactive. To which family does bromine belong? • Bromine, a halogen, is one electron short of having 8 valence electrons. It will readily react with an element that can supply that electron.

6. Predict the charge of a beryllium ion. • Beryllium is an alkaline-earth metal. Therefore, it has two valence electrons that can be removed to form a Be2+ ion.

7. Identify which element is more reactive: lithium, Li, or barium, Ba. • Lithium is an alkali metal and is more reactive than an alkaline-earth metal such as barium.

8. Critical Thinking: How can you determine if a metal is an alkali, alkaline-earth, or transition metal? • Check the reactivity of the metal against the reactivities of other alkali, alkaline-earth, and transition metals. The element belongs to the group that is most similar to the element chemically.

Ch. 3: “Atoms & the Periodic Table”