bonding Flashcards
(18 cards)
What do metals consist of?
Metals consist of giant lattices of metal ions (cations) in a sea of delocalised electrons.
What is metallic bonding?
Metallic bonding is the strong electrostatic attraction between cations and the delocalised electrons.
What are some physical properties of metals?
Metals typically have high melting temperatures, good electrical conductivity, good thermal conductivity, malleability, and ductility.
How does the number of outer-shell electrons affect electrical conductivity?
The electrical conductivity of a metal generally increases as the number of outer-shell electrons increases.
What are delocalised electrons?
Delocalised electrons are outer-shell electrons that are free to move throughout the metal structure and are not confined between any pair of cations.
What must be overcome to melt a metal?
To melt a metal, it is necessary to partially overcome the forces of attraction between the cations and the delocalised electrons.
Why are melting temperatures of metals typically high?
Metals have a giant lattice structure where many forces must be overcome, requiring a large amount of energy, resulting in high melting temperatures.
What should be included in a diagram of metallic bonding for an exam?
Include a key showing ions and electrons.
What is the bonding arrangement in diamond?
In diamond, each carbon atom forms four sigma bonds to four other carbon atoms in a giant three-dimensional tetrahedral arrangement. All bond angles are 109.5°.
Why is diamond extremely hard?
Diamond is extremely hard because of the very strong C-C bonding throughout the structure.
What is the melting temperature of diamond?
Diamond has a very high melting temperature because a great number of strong C—C bonds have to be broken to melt it.
What nickname is sometimes given to diamond and why?
Diamond is sometimes referred to as ‘ice’ due to its properties rather than its appearance.
How does diamond conduct heat?
Diamond conducts heat well due to the network of strong covalent bonds, making it one of the best conductors of heat.
What is the structure of graphite?
Graphite has a layered structure where each carbon atom is bonded to three others by sigma bonds, forming interlocking hexagonal rings.
What is the role of p-orbitals in graphite?
The fourth electron on each carbon atom is in a p-orbital, allowing for overlapping p-orbitals that produce a cloud of delocalised electrons.
Why is graphite used as a solid lubricant?
Graphite can be used as a solid lubricant since the layers slide easily over one another.
How does graphite conduct electricity?
Graphite is a fairly good conductor of electricity, with delocalised electrons free to flow parallel to its layers.
What is graphene?
Graphene is pure carbon in the form of a very thin sheet, one atom thick, bonded in the same way as in graphite.
