halogens

halogens

• The elements in Group 7 are called halogens. They belong to the column second from right in the periodic table.
• The halogens are non-metals with molecules which each contain two atoms.
• They have low melting points and boiling points,
• They are poor conductors of heat and electricity.
• They react with metals to make ionic compounds in which the halide ions have a -1 charge.

• As you go down the group the halogens' melting and boiling points get higher, their colour becomes darker, and they become less reactive. A more-reactive halogen can displace a less-reactive halogen from its salt dissolved in water.

alkali metals

alkali metals :

• The atoms of the elements in Group 1 all have one electron in their highest energy level,the outer shell,this is why their chemical propeties are similar.
• When you write the electronic structure of an alkali metal, the last number must be a 1.
• The alkali metals have low melting and boiling points compared to most other metals
• The alkali metals are very soft.
• Lithium is the hardest alkali metal and they become softer as you go down the group.
• alkali metals become more reactive as you go down the group,
• here is some examples of what happens to lithium,sodium and potassium react with water

lithium + water lithium hydroxide + hydrogen2Li(s) + 2H2O(l) 2LiOH(aq) + H2(g)

When added to water, lithium floats. It fizzes steadily and becomes smaller until it disappears

chemistry

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