Atoms, elements and compounds

This is a brief summary of Atoms, Elements and Compounds

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Atoms consist of protons neutrons and electrons.

PROTONS- in the nucleus and are heavy with positive charge +1

NEUTRONS- in the nucleus and are heavy with zero charge 0

ELECTRONS- are in the outer shells of the atom and are light with negative charge.  -1

An atom is the smallest part of an element. Each atom has the same number of protons, This is called the atomic number

The number of protons and neutrons added together is the mass number or the nucleon number.

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All materials are made up of elements

An element is a substance made up of only one type of atom.

In every element each atom has the same number of protons. In most elements, there are different variations with varying numbers of neutrons

Atoms of the same number but with different numbers of neutrons are called isotopes. Some isotopes are reactive. They decay over time and become less radioactive

Metal elements are shiny solids, good conductors of heat and non magnetic

Non-metal elements are not shiny, poor conductors of heat and non-magnetic

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A compound is a substance which has been formed from the atoms of two or more elements which have been joined together in a chemical reaction.

4 examples of a compound

·         Formation of carbon dioxide (C02), formed by carbon and oxygen.

·         Formation of water (H20), formed by two gases, hydrogen and oxygen

·         Formation of sodium chloride (NaCL), formed sodium and chlorine

·         Formation of copper sulphide (CuS) formed by copper and sulphur

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chlorine should have a letter Cl not a capital letter CL

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