Macromolecules (Giant Covalent Structure)

The ‘lead’ in pencil is made of a mixture of graphite and clay.

If the percentage of graphite is increased, the pencil slides across the paper more easily.

Why is this?

• Graphite conducts electricity.

• Graphite is a form of carbon.

• Graphite is a lubricant.

• Graphite is a non-metal.

The diagram shows a structure of a substance.

What is represented?

• diamond

• silica

• graphite

• ethane

Tags

NGSS.HS-PS1-3

The diagrams show the structures of two forms, P and Q, of a solid element.

What are suitable uses of P and Q, based on their structures?

• use of solid P: drilling

  use of solid Q: drilling

• use of solid P: drilling

  use of solid Q: lubricating

• use of solid P: lubricating

  use of solid Q: drilling

• use of solid P: lubricating

  use of solid Q: lubricating

Rescuers are drilling through fallen rock in order to rescue some men trapped in a cave. The drill needs lubricating from time to time.

The following statements were made about the materials used for the drill tip and the lubricant and the reasons for their use.

Which statements are correct?

• Diamond was used for the drill tip as it does not conduct electricity.

• Diamond was used for the drill tip as it is very hard.

• Graphite was used as the lubricant as it conducts electricity.

• Graphite was used as the lubricant as it is soft and flaky.

Graphite is a form of carbon.

Why can graphite be used as a lubricant?

• Graphite contains delocalised electrons which move throughout the structure.

• Graphite contains weak covalent bonds so the atoms move easily.

• Graphite has a low melting point so it easily turns into a liquid.

• Graphite has weak forces of attraction between layers so they can move.

Tags

NGSS.HS-PS2-6

Which statements are correct about diamond and graphite?

• They are different solid forms of the same element.

• They each conduct electricity.

• They have atoms that form four equally strong bonds.

Tags

NGSS.HS-PS1-3

NGSS.HS-PS2-6

Which substance is not a macromolecule?

• diamond

• graphite

• silicon (IV) oxide

• sulfur

Tags

NGSS.HS-LS1-6

Which substances have similar structures?

• diamond and graphite

• diamond and silicon(IV) oxide

• graphite and poly(ethene

• graphite and silicon(IV) oxide

Tags

NGSS.HS-PS1-3

How many silicon atoms are bonded to each oxygen atom in a crystal of silicon(IV) oxide?

• 1

• 2

• 3

• 4

Which statement about graphite and diamond is correct?

• Diamond has a high melting point but graphite does not.

• Graphite and diamond both conduct electricity.

• Graphite and diamond both have giant structures.

• Graphite is ionic and diamond is covalent.

Tags

NGSS.HS-PS1-3