7.1

Write the symbol for the ion formed when each of the following elements loses its valence electrons. a. aluminum b. lithium c. barium d. potassium e. calcium f. strontium

a. Al+ b. Li+ c. Ba+ d. K+ e. Ca+ f. Sr+

To which group in the periodic table does each of the following elements belong? How many valence electrons do atoms of each element have? a. nitrogen b. lithium c. phosphorous d. barium e. bromine f. carbon

a. Group 5A; 5 valence electron b. Group 1A; 1 valence electron c. Group 5A; 5 valence electrons d. Group 2A; 2 valence electrons e. Group 7A; 7 valence electrons f. Group 4A; 4 valence electrons

State the number of electrons either lost or gained in forming each ion. a. Br- b. Na+ c. As3- d. Ba2+ e. Ca2+ f. Cu+ g. H- h. Cu2+

a. 1 b. 1 c. 3 d. 2 e. 2 f. 1 g. 1 h. 2

What is a valence electron?

The electrons in the highest occupied energy level of an element's atoms

How many electrons must an atom of each element lose to obtain a noble-gas electron configuration? a. Ca b. Al c. Li d. Ba

a. 2; a calcium atom has two valence electrons, which it can lose b. 3; an aluminum atom has 3 valence electrons, which it can lose c. 1; a lithium atom has 1 valence electron, which it can lose d. 2; a barium atom has 2 valence electrons, which it can lose

How many electrons must be gained by each of the following atoms to achieve a stable electron configuration? a. N b. S c. Cl d. P

a. 3; a nitrogen atom has 5 valence electrons. It achieves an octet by gaining 3 electrons. b. 2; a sulfur atom has 6 valence electrons. It achieves an octet by gaining 2 electrons. c. 1; a chlorine atom has 7 valence electrons. It achieves an octet by gaining 1 electron. d. 3; a phosphorous atom has 5 valence electrons. It achieves an octet by gaining 3 electrons.

What is the formula of the ions formed when atoms of the following elements gain or lose valence electrons and attain noble-gas configurations? a. sulfur b. sodium c. fluorine d. phosphorous

a. A sulfur atom has 6 valence electrons and gains 2 electrons to attain a noble-gas configuration. The formula of the ion formed is S2-. b. A sodium atom has 1 valence electron and loses one electron to attain a noble gas configuration. The formula of the ion formed is Na+. c. A fluorine atom has 7 valence electrons and gains 1 electron to attain a noble-gas configuration. The formula of the ion formed ins F-. d. A phosphorus atom has 5 valence electrons and gains 3 electrons to attain a noble-gas configuration. The formula of the ion formed is P3-.

Name each ion in Problem 36. Identify each as an anion or a cation.

a. anion b. cation c. anion d. cation e. cation f. cation g. anion h. cation

Describe two ways that an ion forms from an atom.

an atom or group of atoms loses or gains electrons