Matter was considered to be anything solid out of which tools could be made. This was mainly rocks and bones, because the cavemen didn't have much use for a more sophisticated theory of matter.
The Earliest Chemists
6000 BC - 1000 BC
Early chemists produced valuable metals such as gold and copper.
4500 BC - 1200 BC
Chemists experimented with metals and found that the heating of copper produced bronze,which was then used as material for tools
The Iron Age
1200 BC - 500 BC
Iron was combined with carbon to make steel for stronger tools. It was also in this time period that the Hittites first discovered how to extract iron from rocks and melt it into pots and pans.
The Greek Philosophers
500 BC - 350 BC
Democratis- Believed that all matter could be divided into tiny, indivisible bits called "atomos"
Aristotle- Believed that everything was made up of a mixture of water, earth fire and air.
1500 AD - 1600 AD
Alchemists were the first modern chemists, although they weren't scientists. They believed it was possible to change metal into gold, and this was their main goal. They conducted the first chemistry experiments.
1627 - 1691
Boyle experimented with gasses and what happened to them under pressure. it as through these experiments that eh concluded that matter was made of tiny particles, which is a major part of out modern theory of matter.
1743 - 1794
Named "The Father of Modern Chemistry, he developed a system for naming elements. He named both Hydrogen and Oxygen, predicted silicon and was one of the first to establish sulphur as an element rather than a compound.
1766 - 1844
Dalton was the first person to define elements as pure substances. e also came up with the "billiard ball" model of an atom, which was the first theory of atomic structure. He also did research into colour-blindness, which is sometimes called daltonism in his honour.
1856 - 1940
Thomson discovered electrons and first developed the "Raisin Bun" or "Plum Pudding" model of an atom. This showed the atom as a positive sphere with electrons (negative charges) embedded in it. He was awarded the 1906 Nobel Prize for his work.
1865 - 1950
Nagaoka produced the "Solar System" model of an atom, in which the atom was a positive sphere with electrons orbiting around it. He was a pioneer of Japanese physics during the early Meiji Period.
1885 - 1962
Developed the "Electron Shell" model of an atom in which electrons move in specific shells, or orbits, around the nucleus. He made foundational structure to the modern understanding of atomic structure and quantum mechanics. He won the Nobel Physics Prize in 1922 for his work.
1891 - 1974
Chadwick discovered the Proton (positive charge) and the Neutron (no charge) in the nucleus. He went on to win the Nobel Prize in Physics in 1935.
The quantum mechanics model of an atom used today shows that an atom is a cloud of electrons surrounding the nucleus.