Final answer:
The octet rule states that atoms tend to form bonds so that each atom shares or has eight electrons in its highest occupied energy level. This rule applies to most atoms and is important for understanding chemical bonding.
Step-by-step explanation:
The octet rule is a fundamental concept in chemistry. It states that atoms tend to form bonds in such a way that each atom shares or has eight electrons in its highest occupied energy level. This rule applies to most atoms, except for hydrogen and helium.
When atoms have fewer than eight electrons, they tend to react and form more stable compounds.
For example, oxygen has six electrons in its valence shell, so it is likely to react with other atoms in a way that adds two electrons to its valence shell, bringing the total to eight.
When oxygen reacts with two hydrogen atoms, each sharing its single electron, a covalent bond is formed, resulting in the molecule of water, H2O.