Covalent Substances - Two Kinds

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  • Created by: joshd
  • Created on: 01-04-14 13:21
What do the atoms in simple molecular covalent substances make?
Very strong covalent bonds to form small molecules of two or more atoms.
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What are the forces of attraction like in simple molecular covalent substances?
Very weak.
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What is the result of the feeble inter-molecular forces?
The melting and boiling points are very low, because the molecules are easily parted from each other.
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What are most molecular substances at room temperature?
Gases or liquids.
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Why don't molecular substances conduct electricity?
There are no ions.
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How can you usually tell a molecular substance?
From it's physical state, which is always kinda 'mushy' - i.e, liquid or gas or an easily-melted solid.
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What are similar to ionic lattices, except for?
Giant Molecular Covalent Substances, except there are no ions.
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What are all the atoms bonded by in giant molecular covalent substances?
To each other by strong covalent bonds.
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What do giant molecular covalent substances have?
They have very high melting and boiling points.
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What is an except for the melting and boiling points for giant molecular covalent substances?
Graphite, which don't conduct electricity, not even when molten.
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Describe about solubility and giant molecular covalent substances.
They are usually insoluble in water.
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What are the main examples of giant molecular covalent substances?
Diamond and graphite, which are both made only from carbon atoms.
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What makes diamond really hard? What does this make?
Each carbon atom forms four covalent bonds in a very rigid giant covalent structure. This makes diamonds great as cutting tools. It doesn't conduct electricity because there are no free electrons.
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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. This makes graphite useful as a lubricant.
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How are the layers of graphite held together ?
The layers are held together so loosely that they can be rubbed off onto paper - that's how a pencil works.
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Why can graphite be used in electrodes?
As only three out of each carbon's 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. This means that graphite can be used in electrodes.
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Other cards in this set

Card 2

Front

What are the forces of attraction like in simple molecular covalent substances?

Back

Very weak.

Card 3

Front

What is the result of the feeble inter-molecular forces?

Back

Preview of the front of card 3

Card 4

Front

What are most molecular substances at room temperature?

Back

Preview of the front of card 4

Card 5

Front

Why don't molecular substances conduct electricity?

Back

Preview of the front of card 5
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