The Periodic Table
In the periodic table, the elements are arranged in rows, one above the other. Each row is a period. The most obvious repeating pattern is from metals on the left to non-metals on the right. Every period starts with a very reactive metal in group 1 and ends with a unreactive gas in group 8.
Elements with similar properties fall into a column. Each column is a group of similar elements.
On the periodic table each element is in a box containing two numbers. The number above the element symbol is called the relative atomic mass. The number below the element symbol is called the proton number.
The Alkali Metals
- very reactive
- They are so reactive that they have to be kept under oil to stop the reacting with oxygen or moisture in the air.
- They are called alkali metals because when they react with water they produce a solution that is alkali.
Note that it is the compounds of these metals which are alkalis and not the metals themselves.
- able to be cut with a knife
- shiny but tarnish quickly in air.
- good conductors of electricity.
- they float on water
- melt on gentle heat
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