Question

Explain the physical properties of metals with suitable examples

Answer 1

The physical properties of metals are:-

Malleable and ductile:

1. The layers of metal ions present in the structure of metals slide over each other whenever a certain force is applied.
2. This tells us that the layers of the metal can be hammered and made flat, and they can also slide over each other in order to make thin wires.
3. This change in the shape of the metals is possible due to the metallic bonding.
4. For example, thin sheets of Aluminium(Al) are used as Aluminium foils (malleable), and Copper(Cu) can be converted into wires.

Good conductors of heat and electricity:

1. Due to the presence of free electrons, the conduction of electricity is possible in metals.
2. As the molecules in metal are closely packed to each other, the conduction of heat is also possible.
3. For example, Silver(Ag) are good conductor of heat, and Copper(Cu) is used as a wire for conducting electricity as it is a good conductor of electricity.

Metals are lustrous:

1. Due to the presence of free electrons in the metals, they are lustrous.
2. These free electrons move freely in the metal, as a result, causing any light which is incident on them to get reflected back.
3. Rather than being diffused this reflection is a specular reflection and due to this reason, the metal surface appears shiny or lustrous.
4. For example, Gold(Au) is polished as a result it is lustrous.

Metals are hard:

1. Metals have a lot of free electrons.
2. These electrons thus create a huge electron pressure. ( On the order of ${10}^{5}atm$).
3. As a result, we require a force greater than this internal pressure to cut through the metal.
4. This is the reason why metals are hard, except for Sodium(Na) and Potassium(K) which can be cut through using knives.
5. For example, Chromium(Cr) is a very hard metal$(687-6500Mpa)$.

Metals are solid at room temperature:

1. Metal has large intermolecular forces between its atoms.
2. As a result the interstitial spaces get reduced and a definite shape is acquired by them.
3. Thus we need a large amount of kinetic energy to overcome this attractional force in order to change the state which is not possible at room temperature.
4. Hence metals are solid at room temperature except for Mercury(Hg) and Gallium(Ga) which are liquid at room temperature.
5. For example, Iron(Fe) is solid at room temperature.

Metals have high densities:

1. The elements of the metal due to the electrostatic attraction between them are tightly packed in the lattice.
2. This results in the metal ions in the formation of a three-dimensional packed crystal shape to the metal.
3. Thus metal atoms stay close to each other in large numbers.
4. This is why metals have high density, except for Lithium(Li) which has the least density among other metals.
5. For example, Osmium(Os) has the highest density of $22.59g/c{m}^3$ among the metals.

Metals are sonorous:

1. Due to the very low electronegativity, electron bonding in metals is highly delocalized.
2. This means that when we hit it, the electron cloud moves extremely easily because very little energy is dissipated.
3. As a result of this the incoming kinetic energy is easily propagated in the form of a wave, which creates a sound.
4. For example, Aluminium(Al) and Copper(Cu) are sonorous, that is they produce sound on hitting.

Metals have a high melting point and boiling point:

1. In a metal, the molecules are held together by a strong molecular force of metallic bond which forms a hard lattice structure.
2. This metallic bond is formed as a result of the force of attraction of metal ions and delocalized electrons.
3. In order to break this structure, a lot of energy is required which ultimately results in higher melting and boiling points.
4. For example, Tungsten(T) has the highest melting and boiling points of $3695\mathrm{K}$and $6203\mathrm{K}$ respectively.

Therefore, metals have a lot of physical properties like, being malleable and ductile, hard, lustrous, having high melting and boiling points, having high densities, being sonorous, good conductors of electricity and heat, and are also solid at room temperature.