Chapter 2 - Atoms, Molecules, and Ions - Questions and Exercises - Exercises - Page 85: 2.60

(a) representative (b) transition metal (c) representative (d) inner transition metal

(a) Br, or bromine, is a representative element because it is a main-group element, meaning it is in the "A" group elements. Bromine is in group 7A of the periodic table. (b) Platinum, or Pt, is a transition metal because it is in the middle section of the periodic table called the "B" section. Platinum is in group 8B of the periodic table. (c) Rubidium, or Rb, is a representative element because it is a main-group element, meaning it is in the "A" group elements. Rubidium is in group 1A of the periodic table. (d) U, or uranium, is an inner transition metal because it is in the series called the actinide series. Any element that follows either lanthanum or actinium is considered an inner transition metal.