Chapter 2 - Atoms, Molecules, and Ions - Questions and Exercises - Exercises - Page 85: 2.53

(a) Rubidium (Rb) (b) Ruthenium (Ru) (c) Iodine (I) (d) Xenon (Xe)

(a) Elements in the same group are in the same column on the periodic table. The fifth period is the row that begins with rubidium (Rb) and ends with xenon (Xe). The element in this row that is in the same column as sodium (or Na) is rubidium (Rb). (b) Elements in the same group are in the same column on the periodic table. The fifth period is the row that begins with rubidium (Rb) and ends with xenon (Xe). The element in this row that is in the same column as Fe (or iron) is ruthenium (Ru). (c) Elements in the same group are in the same column on the periodic table. The fifth period is the row that begins with rubidium (Rb) and ends with xenon (Xe). The element in this row that is in the same column as bromine (or Br) is iodine (I). (d) Elements in the same group are in the same column on the periodic table. The fifth period is the row that begins with rubidium (Rb) and ends with xenon (Xe). The element in this row that is in the same column as Ne (or neon) is xenon (Xe).