Metallic bonding

Nature of science:

Use theories to explain natural phenomena—the properties of metals are different from covalent and ionic substances and this is due to the formation of non-directional bonds with a “sea” of delocalized electrons. (2.2)

• A metallic bond is the electrostatic attraction between a lattice of positive ions and delocalized electrons.
• The strength of a metallic bond depends on the charge of the ions and the radius of the metal ion.
• Alloys usually contain more than one metal and have enhanced properties.

Applications and skills:

• Explanation of electrical conductivity and malleability in metals.
• Explanation of trends in melting points of metals.
• Explanation of the properties of alloys in terms of non-directional bonding.

Guidance:

• Trends should be limited to s- and p-block elements.
• Examples of various alloys should be covered.

• The availability of metal resources, and the means to extract them, varies greatly in different countries, and is a factor in determining national wealth. As technologies develop, the demands for different metals change and careful strategies are needed to manage the supply of these finite resources.

Utilization:

• Syllabus and cross-curricular links:
• Option A.6—use of metals in nanotechnology
• Biology topic 2.2—water

Aims:

• Aim 1: Global impact of value of precious metals and their extraction processes and locations.
• Aim 7: Computer simulations could be used to view examples of metallic bonding.