-
450 BCE
Aristotle
Aristotle discovered the main elements were fire, water, earth and air -
6 BCE
Alchemist
Alchemist used a variety of symbols to identify each element and made many different discoveries to the modern science of chemistry.
e.g. gold (the picture on the left) -
Antoine Lavoiser
Lavoiser found that mass is conserved in a chemical reaction -
Joseph Proust
He was best know for the discovery of the law of constant composition which he stated that chemical compounds always combine in constant proportions. -
John Dalton
John Dalton created the very first atomic theory he viewed atoms as tiny, solid balls and had 4 statements for the atomic theory which were: atoms are tiny, invisible particles, atoms of one element are all the same, atoms of different elements are different and compounds form by combining atoms. -
J.J Thomson
He discovered electrons and was the first scientist to show that the atom was made of even smaller things. He also proposed the existece of positive particles. -
Ernest Rutherford
He showed that atoms have positive particles in the centre and are mostly empty space, these positive particles are called protons and the centre of the atom is called the nucleus. -
James Chadwick
Chadwick discovered the neutrons he was working with Ernest Rutherford and found out that particles with no charge were called neutrons which were located in the nucleus.
