Question

Which of the following properties are better considered characteristic of the free isolated atoms, and which are characteristic of the bulk metal: (a) electrical conductivity, (b) first ionization energy, (c) atomic radius, (d) melting point, (e) heat of vaporization, (f) electron affinity?

Short answer

In summary, the properties more characteristic of free isolated atoms are (b) first ionization energy, (c) atomic radius, and (f) electron affinity. The properties more characteristic of bulk metals are (a) electrical conductivity, (d) melting point, and (e) heat of vaporization.

Step-by-step solution

(a) Electrical conductivity

Electrical conductivity is the measure of a material's ability to conduct an electric current. Free isolated atoms do not possess this property as they lack the mobile electrons required for the movement of electrical charge. In contrast, bulk metals have free electrons that can move through the crystal lattice, enabling conductance. Thus, electrical conductivity is more characteristic of bulk metals.

(b) First ionization energy

The first ionization energy is the energy required to remove an electron from a neutral atom in its gaseous state. This property relates to individual atoms, as it describes their electron behavior. Therefore, first ionization energy is more characteristic of free isolated atoms.

(c) Atomic radius

The atomic radius is the measure of the size of an atom. It can be determined by measuring the distance between the nuclei of two bonded atoms and dividing by two. This property is directly related to individual atoms, as it represents the atomic size. Thus, the atomic radius is more characteristic of free isolated atoms.

(d) Melting point

The melting point is the temperature at which a substance changes from a solid to a liquid state. Melting points are relevant to bulk materials, where the intermolecular forces need to be conquered. Hence, the melting point is more characteristic of bulk metals.

(e) Heat of vaporization

The heat of vaporization is the amount of energy required to convert a substance from its liquid state to a gaseous state at a constant temperature. This property applies to bulk materials, as it refers to the energy needed to break intermolecular forces in a group of molecules or atoms. Therefore, the heat of vaporization is more characteristic of bulk metals.

(f) Electron affinity

Electron affinity is the amount of energy released or spent when an electron is added to a neutral atom, forming a negative ion. This property relates to individual atoms because it describes their behavior when gaining an electron. Consequently, electron affinity is more characteristic of free isolated atoms. In summary, the properties that are more characteristic of the free isolated atoms are first ionization energy, atomic radius, and electron affinity. The properties that are more characteristic of the bulk metal are electrical conductivity, melting point, and heat of vaporization.