Читать книгу Foundations of Chemistry - Philippa B. Cranwell - Страница 83

Metallic bonding occurs in metals and alloys when metal atoms are bonded to other metal atoms. When metal atoms join together, their outer (valence shell) electrons are lost, leaving positively charged metal ions. The electrons form a ‘sea’ of negative charge surrounding the positive metal ions. The interaction between the sea of electrons and the positive metal centres holds the atoms together in the bulk metal. A representation of the bonding in sodium is shown in Figure 2.2. Sodium is in Group 1 and has only one outer electron that is easily lost. The positive sodium ions form a regular ordered array surrounded by the sea of negative electrons.

The valence shell is the outermost shell in an atom that contains electrons.

An ion is an atom that has lost or gained one or more electrons to form a charged species. A positive ion is called a cation, and a negative ion is called an anion.

Figure 2.2 Bonding in sodium metal.