Metallic crystals

Metallic crystals are crystalline solids formed by atoms of the same metallic element, held together by a metallic bond.

Metallic bond : In a solid metal, the valence electrons are delocalised over the entire crystal, leaving behind positively charged metal ions. Metallic crystals are therefore often described as an array of positive ions immersed in a sea of mobile electrons; the attractive interactions between the cations and the mobile electrons constitute the metallic bonds. (For more details refer to section 1.9.2.)

Metallic crystals have the following properties:

i. Metals are malleable -- they can be hammered into thin sheets.

ii. Metals are ductile -- they can be drawn into wires.

iii. Metals have good electrical and thermal conductivity. The delocalised electrons move freely through the crystal under an applied electrical potential or a temperature difference, which is what makes both kinds of conduction possible.

Examples: metals such as Na, K, Ca, Li, Fe, Au, Ag, Co, etc.

The properties of the different types of crystalline solids are summarized in Table 1.1.

Table 1.1 : Properties of four types of crystalline solids