Covalent Bonding Flashcards
Covalent bonds:
Sharing electrons
Why do electrons share a pair of electrons:
As this way both atoms feel they have a full outer shell, and that makes them happy
What does each covalent bond provide:
One extra shared electron for the atom
What does each atom involved in covalent bonding have to do:
Make enough covalent bonds to fill up its outer shell
What happens when atoms make covalent bonds with one or more other atoms:
They form a molecule
What do simple molecule covalent substances atoms in these substance make:
Very strong covalent bonds to form small molecules of two or more atoms
What are the forces of attraction like in simple molecular covalent substances:
Forces of attraction between the molecules are very weak
What is the boiling and melting point like in a simple molecular covalent substance:
Very low melting and boiling point because the molecules are easily parted from each other
What are most simple molecular substances at room temperature:
Gases or liquids
What do simple molecular substances don’t do:
Don’t conduct electricity, as there are no ions
What are Giant molecular covalent substances similar to:
Ionic lattices except that there are no charged ions
How are atoms bonded in a giant molecular substance:
All atoms are bonded to each other by strong covalent bonds
What is the melting and boiling point like in Giant molecular substances:
Have very high melting and boiling points
Do Giant Molecular substances conduct electricity:
Don’t conduct electricity (except for graphite) - not even when molten
What are giant molecular substances usually like in water:
Insoluble
What makes diamond really hard:
Each carbon atom forms four covalent bonds in a rigid giant covalent structure, which makes diamond really hard.
Why dosen’t diamond conduct electricity:
As there are no free electrons
What is diamond:
The hardest natural substance
Why is graphite useful as a lubricant:
Each carbon atom only forms three covalent bonds, creating sheets of carbon atoms which are free to slide over each other.
How is graphite a good conductor of electricity:
As only three out of each carbons four outer electrons are used in bonds, there are lots of spare delocalised electrons. These electrons can move, so graphite is a good conductor of electricity.
As graphite is a good conductor of electricity this means that:
Graphite can be used in electrodes
What do diamond and graphite have in common:
Both made of carbon
Both giant covalent
Properties of diamond:
Hardest natural substance
Can’t conduct electricity - no free electrons
Insulator
4 bonds
Crystalline
Properties of graphite:
Layers can slide
Good conductor of electricity - delocalised electrons that can move
3 bonds
