Fundamental Ideas


All substances are made of elements.  The Periodic Table is a list of all the known elements. Each element is made of one type of atom.  Atoms are represented by chemical symbols.

Elements in the Periodic Table are arranged in groups.  Groups are vertical columns and elements in the same group have similar properties.  

When elements react, their atoms join with atoms of other elements and compounds are formed.


The nucleus is situated at the centre of an atom and contains two types of particle - protons and neutrons.  Electrons are tiny, negatively charged particles that orbit the nucleus.

An atom has no overall charge because the number of protons (+1 charge) always equals the number of electrons (-1 charge).  Neutrons have no charge.  All atoms of an element contain the same number of protons.  The number that denotes the number of protons an atom has is called the atomic or proton number.  Elements in the Periodic Table are arranged in order of atomic number.  The atomic number


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