Chemistry

elements

An element is a pure substance consisting of only one type of atom.

It is distinguished by it’s atomic number, or the number of protons in it’s nucleus.

atoms

An atom is a basic unit of matter. Also it is the smallest recognized division of a chemical element.

metalsA metal is a chemical element, compound or alloy, characterised by high electrical and heat conductivity. It’s also ductile (it can be stretched without breaking) and tensile (it can be bent without breaking).

non-metalsA non-metals (such as hydrogen & carbon) are poor conductors of heat & electricity, and are dull and brittle in solid form. The usually have lower densities, freezing points and boiling points than metals.

the periodic table

The periodic table is a display of all the pure chemical elements. The current standard table contains 117 elements.

compounds

A compound is two or more different elements fused together. Some examples are aluminium, baking soda and tin.

chemical reactionsA chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Examples are a plant changing sunlight into energy or metal going rusty.

identificationYou can tell if there is a chemical reaction happening because either heat, light, precipitate or gas will be produced.

Chemical changes

A chemical changes is when the bonds of an object are broken and new bonds are formed, creating a new substance (e.g. cooking, corn kernals into popcorn).

physical changes

In a physical change, the substance doesn’t change chemically at all, but takes on a different form (e.g. water freezing and melting)

reaction rateA reaction rate is the rate that two substances combine to form a chemical reaction. For example, iron rusting is a slow reaction rate. Fire burning a log into charcoal is a fast reaction rate.

Factors of reaction rate. Concentration – how diluted or pure the substance is.. Temperature – how hot/cold the environment is.. Catalyst – whether or not there is another substance to provide a pathway.. Surface area – powder is going to dissolve faster than a tablet.