Why do metals have high melting points?

Metals have high melting points due to the strong metallic bonds that hold their atoms together.

Metals are made up of a lattice of positive ions surrounded by a 'sea' of delocalised electrons. This structure is often referred to as a 'metallic lattice'. The strong electrostatic attraction between the positive ions and the delocalised electrons is what forms the metallic bond. This bond is very strong and requires a lot of energy to break, which is why metals have high melting and boiling points.

The strength of the metallic bond varies between different metals, which is why different metals have different melting points. For example, tungsten has one of the highest melting points of any metal because it has a very strong metallic bond. This is due to the large number of delocalised electrons in tungsten, which increases the strength of the electrostatic attraction between the positive ions and the electrons.

In contrast, metals like mercury have relatively low melting points because they have fewer delocalised electrons and therefore weaker metallic bonds. However, even metals with low melting points still require a significant amount of energy to melt compared to many non-metals.

In summary, the high melting points of metals can be attributed to the strong metallic bonds that hold their atoms together. The strength of these bonds is determined by the number of delocalised electrons, with more electrons leading to stronger bonds and higher melting points.