Chemical equations and formulae

Atoms - The smallest part of an element that can exist. The average size of it is normally 0.1nm.

• Contains 3 subatomic particles :
  • Proton - Has a relative charge of +1 and a relative mass of 1. The number of protons in each atom are unique to each element (They are not lost or recieved during any chemical changes).
  • Neutron - Has a relative charge of 0 and a relative mass of 1. The number of neutrons in the atom of the same element can differ.
  • Electron - Has a relative charge of -1 and a relative mass of 1/1836. They can be lost or taken in by the atom in a chemical reaction but initially, the number of electrons = number of neutrons.
• The nucleus holds the protons and electrons of an atom and all the mass is concentrated in the nucleus.
• Below, you can see the structure of an atom :

Element - A substance made of only one type of atom.

• An atom of a particular element is defined by the number of protons it contains.
• There are about 100 different elements as listed in the periodic table.
• Each element is represented by a symbol such as Na = Sodium, O = Oxygen
• Each element is also given a nuclear symbol. You can…