Chemistry 4.1 Flashcards
Covalent bonding
Electrostatic attraction between the nuclei of bonded atoms and a shared pair of electrons
Reason for low melting point for simple molecular substances
Weak intermolecular forces between molecules are easy to break/overcome
Electrical conductivity in simple molecular substances
No charged particles, molecules are neutral. Electrical conductivity requires charged particles which are free to move.
Why is C60 fullerene’s boiling point not as low as other simple molecular substances?
It has a high molecular mass, molecules are large and heavy. Intermolecular forces are fairly strong and require quite a bit of energy to break.
Why is C60 fullerene soft and slippery?
Molecules can roll over each other easily due to the weak forces between molecules.
Is C60 fullerene simple molecular or giant covalent?
Simple molecular
What type of elements use covalent bonding?
Only non-metals
Properties of covalent bonding
Low MP/BP
Insulator
Structure of diamond
Giant lattice. Every carbon makes 4 covalent bonds. Tetrahedral lattice/structure. Carbon atoms are fixed strongly in place.
Why does diamond sublime at a very high temperature?
Giant covalent structure, giant lattice so there are lots of covalent bonds. The covalent bonds are very strong. Takes large amounts of energy to overcome/break all the bonds.
Why is diamond used for cutting tools? Make reference to its structure and bonding.
It is very hard. Every carbon makes 4 covalent bonds, tetrahedral structure/lattice. Carbon atoms are fixed strongly in place. Lots of strong covalent bonds.
Use for diamond
Drill bits/cutting tools
Electrical conductivity of diamond
Can’t conduct electricity. No freely-moving charged particles. No delocalised electrons because they are all stuck in covalent bonds. All atoms are neutral.
Structure of Graphite
Each carbon atom bonded to 3 others leaving 1 free delocalised electron per carbon atom. Layers of hexagons. Covalent bonds within layers are strong. Layers are attracted to each other by weak intermolecular forces/ weak intermolecular forces between layers. Delocalised electrons.
Why does Graphite sublime at a very high temperature?
Giant covalent structure. Giant lattice so there are lots of covalent bonds. Covalent bonds are very strong so take large amounts of energy to overcome/break.
Why is Graphite soft and slippery/ why can Graphite be used as a lubricant?
Made up of layers of flat sheets which are attracted to each other by weak intermolecular forces, meaning the layers can slide over each other easily and easily break apart.
Electrical conductivity of Graphite
It can conduct electricity. Its structure contains delocalised electrons because each carbon atom has 3 bonds with others so 1 electron per carbon atom is not used in covalent bonds. These electrons are delocalised and are free to move and conduct electricity.
Structure of silicon dioxide
Each silicon atom forms 4 covalent bonds and each oxygen atom forms 2 covalent bonds. Tetrahedral shape (like diamond).
Why does silicon dioxide melt at a very high temperature?
Giant covalent structure so lots of covalent bonds in giant lattice. Covalent bonds are very strong so require lots of energy to overcome/break.
Electrical conductivity of silicon dioxide
Doesn’t conduct electricity. None of its electrons are free to move, all used up in covalent bonds (each silicon atom makes 4 bonds, each oxygen atom makes 2 bonds). No delocalised electrons.
Use of silicon dioxide
Anti-caking agent
What has similair properties to diamond?
Silicon dioxide because of its similair structure and bonding.
