Covalent bondingAtomic structure

A covalent bond is a shared pair of electrons. Covalent bonding results in the formation of molecules or giant structures. Substances with small molecules have low melting and boiling points and do not conduct electricity. Giant covalent substances have very high melting points.

Part ofScienceProperties and uses of substances

Atomic structure

Everything in the world is made from about 100 different chemical elements that join together in different ways to form all the solids, liquids and gases we see around us.

An element is a substance that contains only one type of . As a result, they are the simplest substances known.

All of the elements have been arranged into the periodic table.

The periodic table. An 18-column by seven-row grid of the elements arranged by increasing atomic number. The columns are called groups. Elements in each group tend to have similar properties.

The periodic table can be divided into periods (horizontal rows) and groups (vertical columns).

Elements that are in the same group of the periodic table have similar chemical properties (they react in the same way). Some groups have their own names.

The periodic table. An 18-column by seven-row grid of the elements arranged by increasing atomic number. The columns are called groups. Elements in each group tend to have similar properties.
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Structure of the atom

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