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Flashcards in The Lithosphere C5 Deck (10)
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1
Q

Why does graphite conduct electricity?

A

The carbon atoms only have three covalent bonds leaving four spare delocalised electrons to carry charge.

2
Q

What is a use for graphite and why?

A

Pencils.
The covalent bonds are arranged in sheets with weak forces between these sheets, allowing the pencil to rub off in layers.

3
Q

Describe a use for diamond and why this is a good use…

A

Glass-cutting tool. Diamond has a rigid structure with four covalent bonds making it the hardest structure - it can break other substances.

4
Q

Percentage composition describes…

A

The percentages of minerals and elements in rocks.

5
Q

Describe the lithosphere.

A

The crust and part of the mantle just below it make the Earth’s lithosphere. This mostly consists of a mixture of minerals. The elements silicon, oxygen, and aluminium are found in large amounts in the crust.

6
Q

What are the features of diamond?

A

The carbon atoms form four covalent bonds in a very rigid giant covalent structure.
All the bonds give diamond a high melting point.
Diamond does not conduct electricity as it has no free electrons, not even when molten.
Usually insoluble.

7
Q

What are graphite’s features?

A

Graphite is made from carbon.
It only has three covalent bonds creating sheets that can slide over each other - this makes graphite slippery so good as a lubricant.
The lagers can be rubbed off into paper leaving a black mark.
High melting point.
Spare electrons mean that graphite can conduct electricity - used in electrodes.

8
Q

Describe silicon’s features…

A

Most silicon and oxygen in the crust exists as silicon dioxide.
This is what sand is made of.
Each grain of sand is a giant structure of silicon and oxygen.
A similar structure to diamond with four covalent bonds gives it a high melting point and means it cannot conduct electricity.

9
Q

Diamond and graphite are…

A

Minerals of carbon atoms.

10
Q

Describe giant covalent structures.

A

These contain uncharged atoms. The covalent bonds between the atoms are strong. They have high melting points and are usually insoluble in water.