The Group 7 elements are also known as the halogens. They include fluorine, chlorine, bromine and iodine, which all have seven electrons in their outer shell.
In a displacement reaction a less reactive element is removed and replaced by a more reactive element.
Group 7, also known as the halogens, includes fluorine, chlorine, bromine and iodine. Chlorine is used to sterilise the drinking water supply and in the manufacture of many important chemicals such as pesticides and plastics. Iodine can be used to sterilise wounds.
An important compound of chlorine is sodium chloride or common salt. It's used to preserve food, as flavouring and to manufacture chlorine.
The halogens have similar properties because they all have seven electrons in the outer shell. They all react very vigorously with alkali metals.
|Halogen||Appearance||Reaction with sodium||Reactivity|
|Chlorine||pale green gas||sodium + chlorine → sodium chloride||extremely reactive|
|Bromine||orange liquid||sodium + bromine → sodium bromide||very reactive|
|Iodine||grey solid||sodium + iodine → sodium iodide||reactive|
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