Metallic Bonding

Second in this "series" about bonding is metallic bonding!

Metallic bonds exist between metal atoms. WOW. Bet you didn't see that one coming.

Metallic bonds are different from ionic and covalent bonds not only in that no non-metal ions are involved, but in that electrons aren't shared or transferred between individual atoms. Instead, the nuclei of the metal atoms, roughly lined up in rows, are surrounded by a "sea" of delocalised electrons.

This type of bonding is responsible for the properties which exist in most metals.

Hardness: The metallic bonds between the positively-charged nuclei and the negatively-charged electrons which surround the nuclei are extremely strong, resulting in the metal being hard.

Malleability and ductility: Unlike ionic bonding, if the metal is bumped, the nuclei can slide over each other while maintaining the sea of delocalised electrons. Therefore, the bonds between nuclei and electrons are not broken. This allows the metal to be pulled and stretched in different ways without the metal breaking or snapping. Solder is a good example of this.

How come steel isn't so easy to bend? Most of the time, metals are mixed together to form alloys, which are better at retaining their shape than metals consisting of only one kind of element. This is because different types of metal atoms are differently sized, due to the differing numbers of protons and neutrons in the nuclei of the atoms.

In the above example, because the Pb atom is much bigger than the Fe atoms, it makes it difficult for the two layers of atoms to slide over each other. This is why alloys are less malleable than pure metals, and why pure gold is so malleable while jewellery gold is much less malleable and therefore suitable for wearing.

They're shiny! The reason why metals is so shiny is due largely to the sea of delocalised electrons. These delocalised electrons are pretty good at reflecting light, resulting in metals being shiny.

High melting and boiling points: Because metallic bonds are so strong, a lot of energy is required to break them. Therefore, metals have high melting and boiling points.

High conductivity: Due to the sea of freely-moving delocalised electrons which can carry an electrical charge, metals make great conductors.

Next up is covalent bonding! Stay tuned for the next episode!

(... episode?!)