Simple molecular substances are made up of two or more atoms covalently bonded together to form a distinct unit.

Scientists use models to represent parts of the natural world that are too difficult to observe or explain directly.

Intermolecular forces are weak forces of attraction between molecules and molecular substances.

A giant covalent substance has a large regular arrangement of atoms all joined together by covalent bonds.

Using models to explain state changes

Chemistry

In the Organic chemistry unit, pupils will learn more about hydrocarbons and learning about other homologous series, along with their reactions.

In the Structure and bonding unit, pupils learned about metallic, ionic and covalent bonding and about giant ionic structures, as well as the structure of covalent molecules, beginning to form links to properties

Chemistry of carbon

Which properties of diamond are explained by the fact that each carbon atom is strongly bonded to four other carbon atoms in a rigid structure?

What type of forces hold simple molecules together?

One model of graphite shows it having free moving, delocalised electrons. This means graphite is an electrical {{}}?

doesn't conduct electricity as every atom is strongly bonded to others

hexagonal rings of carbon atoms, arranged in layers

made of simple molecules with low melting and boiling points

Match each substance to the correct statement about it's structure and/or properties.

distinct units made up of two or more atoms covalently bonded

represent parts of the natural world that are too difficult to observe

weak forces of attraction between molecules

large regular arrangement of atoms all joined by covalent bonds

Match the key words to their definitions.

[a] covalent substances have [b] melting points as they're held together by strong covalent bonds. [c] covalent substances have [d] melting points as there are weak forces between molecules.

Below, there are six different models for representing the bonding and structure in the compound ethane. Match the image to the correct type of model.

What do the dots and crosses typically represent in dot-and-cross diagrams?

it does not indicate the actual number of atoms

it does not provide any spatial information

it serves as a step towards determining the molecular formula

Which of the following are limitations of the empirical formula when representing molecules?

Which model would not be appropriate to represent the bonding and/or structure in metals?

It shows the actual size of atoms more accurately.

It clearly shows which atoms/ions have bonded.

It is easier to see the overall shape of the substance.

It is more accurate in depicting electron sharing.

What advantage does the ball-and-stick model have over the space-filling model?

Which representation is most suitable for illustrating the arrangement of ions in a giant ionic lattice?

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Using models to explain state changes

Lesson outcome