Massspectrometry is more often applied to molecules than to atoms. We will see in Chapter 3 that the molecular weight of a molecule is the sum of the atomic weights of the atoms in the molecule. The mass spectrum of H2 is taken under conditions that prevent decomposition into H atoms. The two naturally occurring isotopes of hydrogen are 1H (atomic mass = 1.00783 amu; abundance 99.9885%) and 2H (atomic mass = 2.01410; abundance 0.0115%). (c) Which peak will be the largest, and which the smallest?
The elements of Group 14 show an interesting change in properties moving down the group. Give the name and chemical symbol of each element in the group and label it as a nonmetal, metalloid, or metal.

Key Concepts
Group 14 Elements
Classification of Elements
Trends in the Periodic Table
For each of the following elements, write its chemical symbol, locate it in the periodic table, give its atomic number, and indicate whether it is a metal, metalloid, or nonmetal: (a) radon (b) tellurium (c) cadmium (d) chromium (e) barium (f) selenium (g) arsenic.
For each of the following elements, write its chemical symbol, determine the name of the group to which it belongs (Table 2.3), and indicate whether it is a metal, metalloid, or nonmetal: (a) polonium (b) strontium (c) neon (d) rubidium (e) sulfur.
The structural formulas of the compounds n-butane and isobutane are shown below. (b) Determine the empirical formula of each.
The structural formulas of the compounds n-butane and isobutane are shown below. (c) Which formulas—empirical, molecular, or structural—allow you determine these are different compounds?
Ball-and-stick representations of benzene, a colorless liquid often used in organic chemistry reactions, and acetylene, a gas used as a fuel for high-temperature welding, are shown below. (a) Determine the molecular formula of each.