Crystal Types and Bonding

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  • Created by: ava.scott
  • Created on: 13-04-14 14:14

Ionic Lattices

e.g. sodium chloride

Melting Points

Very high; the electrostatic forces between ions are very strong, and require alot of energy to break.

Electrical Conductivity

Only conducts when molten or dissolved, because then the charged ions are free to move.

Strength

Weak- very brittle. When hit, oppositley charged ions line up and repel eachother.

Solubility

Very soluble- charged ions are attracted to the dipoles of water.

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Simple Molecular

e.g. iodine

Melting Point

low- only weak Van der Waal forces holding molecules together.

Electrical conductivity

None- there are no charged particles to carry a current.

Strength

Weak- only VDW forces to break.

Solubility

Little, as there is no charged or polar molecules.

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Simple Molecular exception- WATER

water/ice

Melting Point-

higher than expected due to hydrogen bonds, which need to be broken.

Electrical conductivity-

Good- molecules are polar so can carry charge.

Strength-

Ice is very strong, as the hydrogen bonds become still and rigid.

Solubility-

universal solvents itself, but polar, so dissolves well in other solvents.

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Giant covalent- diamond

Melting Point

extremely high, as covalent bonds throughout which need huge amounts of energy to break.

Electrical conductivity

no charged particles so not a conductor. the carbon atoms are saturated iwth 4 other carbon atoms

Strength

extremely strong- covalent bonds

Solubility-

None- not polar, and too big. The covalent bonds are way stronger than any water dipole.

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Giant covalent- Graphite

Melting Point

Very high- covalent bonds need to be broken.

Electrical conductivity

Good conductor- the carbon atoms are only bonded to three others, so there are delocalised electrons to carry current.

Strength

Brittle- individual layers are strong, but only weak forces between layers so they can easily slip.

Solubility

None- not polar.

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Metallic

Melting Point

Varies, but generally high. The more electrons an atom commits to the sea of delocalised electrons, the higher the melting point will be. Aluminium contributes 3 electrons, whereas Lithium only commits one.

Electrical conductivity

Very good conductors- the delocalised electrons move randomly until a charge is applied, and they all move towards the cathode, carrying the charge in a current.

Strength

Varies, but generally strong- they absorb energy in their malleability because the protons can move around in the sea of electrons.

Solubility

none- not polar.

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