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Groups and periods are just ways to divide and categorise elements in the periodic table according to their properties- be it physical or chemical. A period is the horizontal line and all the elements in ...

If a reaction is exothermic, it means that it gives out energy, heating up its surroundings, and so the products have less energy than the reactants.

If a reaction is endothermic, it means that it ...

Activation energy is the amount of energy that the reactants need in order to react and become the products. For example, when burning natural gas (also called methane, or CH₄), you need a spar...

A reversible reaction is one where the reaction can occur both ways. Therefore, in a closed system where nothing can escape, some products made will always react in the reverse direction to make the react...

Both alkenes and alkanes are chains of carbon and hydrogen molecules. The chains can be different lengths and each length chain has a different name. 

An alkene is a chain which has a double bond b...