Diamond and graphite | Combined science | Quizalize & Oak National Academy

Starter quiz

The presence of which type of bond is a key feature in giant covalent structures?

Ionic bonds

Covalent bonds ✓

Metallic bonds
Which property is typical of substances with giant covalent structures?

high melting and boiling points ✓

conductivity in their solid state

low melting and boiling points

soluble in water
What distinguishes a giant covalent structure from a simple molecular structure?

the type of atoms involved

the presence of ionic bonds

the size and regularity of the structure ✓

their electrical conductivity

their solubility in water
Which diagram below shows a model of a giant covalent substance?

sodium chloride (NaCl)

silicon dioxide (SiO₂) ✓

nitrogen (N₂)

iron (Fe)
Which properties are typically found in simple molecular substances but not in giant ionic structures?

high electrical conductivity

inability to dissolve in water ✓

low melting and boiling points ✓

flexibility and malleability
In giant covalent structures, atoms are bonded covalently in a large 3D lattice resulting in high melting and boiling points. Match each part of this sentence to the correct term.

bonding

⇔

covalent ✓

structure type

⇔

giant covalent ✓

property

⇔

high melting and boiling points ✓

structure description

⇔

large 3D lattice ✓

What is an allotrope?

a type of chemical bond

a different structural form of an element ✓

a kind of molecular geometry

a category of organic compounds
What makes diamond so hard?

intermolecular forces

delocalised electrons

hexagonal rings

covalent bonds ✓
Why can graphite be used as a lubricant?

strong covalent bonds within atoms

weak intermolecular forces between layers ✓

delocalised electrons

high melting point

ability to conduct electricity
In diamond, each carbon atom forms ______ covalent bonds.

'4' ✓
True or false? In graphite, each carbon atom is bonded to four other carbon atoms.

True

False ✓
Graphite conducts electricity because it has ______ which can move and carry charge/current.

'delocalised electrons' ✓

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In diamond each carbon atom is bonded to four others with strong covalent bonds to form a giant covalent structure.
Diamond is very hard, has a very high melting point and does not conduct electricity (makes it good for cutting tools).
In graphite, each carbon atom is covalently bonded to three others to form layers of hexagonal rings.
There are only weak forces between the layers in graphite which can easily be rubbed apart (makes it a good lubricant).
Graphite conducts electricity because it has delocalised electrons which can move and carry charge/current.

Students may think all carbon forms are alike, ignoring structure's impact on properties.

Emphasise structure-property relationships. Use models to show how diamond's and graphite's differing bonds affect their characteristics.

Allotrope - A different structural form of an element, e.g. graphite and diamond are allotropes of carbon.
Giant covalent - A large regular arrangement of atoms all joined together by covalent bonds.
Forces of attraction - Forces of attraction refer to any force that causes two or more substances to come together.
Delocalised - Particles are said to be delocalised when they are free to move through a structure (delocalised electrons can carry an electrical current).