2 4 giant structures

Giant covalent structures are macromolecules or giant lattices that consist of a huge number of non-metal atoms with strong covalent bonds in a fixed ratio.

Allotropes are different structural forms of the same element, such as diamond and graphite for carbon.

Diamond does not conduct electricity because all of the outer shell electrons are held in the covalent bonds, and there are no freely moving delocalised electrons to carry the current.

False. Graphite is used in pencils, as an industrial lubricant, in inert electrodes, and in locks. Diamond is used in cutting tools.

In graphite:

False. Diamond is harder than graphite.

Diamond does not conduct electricity, has a high melting point, and is extremely hard.

Graphite conducts electricity and heat, has a high melting point, and is soft and slippery.

Graphite conducts electricity because it has delocalised electrons that can move / flow (throughout the structure)

Diamond is hard because its rigid, tetrahedral structure contains a lot of covalent bonds that require a large amount of energy to break.

Graphite is soft because there are weak intermolecular forces betwen the layers, which allows the layers to slide over each other.

Silicon(IV) oxide is a macromolecular compound that occurs naturally as sand and quartz, with the chemical formula SiO2.

In silicon(IV) oxide, each silicon atom forms covalent bonds with 4 oxygen atoms.

True. Silicon(IV) oxide has a tetrahedral structure similar to diamond.

A macromolecular compound is a substance composed of very large molecules with a repeating structure.

Silicon(IV) oxide has similar properties to diamond, including being very hard, having a very high boiling point, being insoluble in water, and not conducting electricity.

Two common uses of silicon(IV) oxide are making sandpaper and lining the inside of furnaces.

False. Silicon(IV) oxide is cheap since it is available naturally.

Silicon(IV) oxide has covalent bonding.

In silicon(IV) oxide, each oxygen atom forms covalent bonds with 2 silicon atoms.

Another name for silicon(IV) oxide is silicon dioxide or silica.

Metallic bonding is the strong electrostatic force of attraction between delocalised electrons and positively charged metal ions.

Delocalised electrons are electrons in metals that do not belong to any particular metal atom and are free to move throughout the metal lattice.

Metals can conduct electricity because they have free electrons available to move and carry charge.

Metals are malleable and ductile because the layers of positive ions can slide over one another.

True. Alloys are created by mixing a metal with another metal or non-metal.

Metals have high melting and boiling points because they contain many strong metallic bonds, which require a lot of heat energy to overcome.

Metal structures are positive metal ions arranged in a regular pattern, with a "sea" of delocalised electrons moving freely between them.

False. Metallic bonds are strong due to the attraction between positive metal ions and delocalised electrons.