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

2. 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

3. 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.

4. 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.

5. 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
d. a conducting material used within flexible wires

6. 5. Describe why atoms of bromine, Br, are so reactive
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.

7. 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.

8. 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.

9. 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.