C3 Revision

• 1) Their physical and chemical properties.
• 2) Their relative atomic mass.

To keep elements with similar properties in the same vertical columns also to leave room for elements that haven't being discovered yet.

The alkali metals have low melting and boiling points compared to most other metals. Apart from the otheralkali metals, only three metals (indium, gallium and mercury) have lower melting points than lithium. You can see from the graph that lithium, at the top of Group 1, has the highest melting point in the group.

• they form coloured compounds
• they are good conductors of heat and electricity
• they can be hammered or bent into shape easily
• they are less reactive than alkali metals such as sodium
• they have high melting points - but mercury is a liquid at room temperature
• they are usually hard and tough
• they have high densities

• Drinks
• Industrial methylated spirits (meths)

• unlike petrol and diesel, hydrogen does not generate carbon dioxide when burnt
• hydrogen fuel cells are very efficient

• The flame test: Red Lithium, Li+.Orange Sodium, Na+. Lilac Potassium , K+. Brick red Calcium, Ca2+
• Using white precipitates

A cell producing an electric current direct from a chemical reaction.

Is energy released when bonds are formed or when bonds are broken?

Shielding effect can be defined as a reduction in the effective nuclear charge and the electronic cloud,due to difference in the attraction forces of the electrons on the nucleus. It is also refereed as the screening effect or atomic shielding.

• Vinegar 
• Soap

Hydrochloric acid.