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570 BCE
Democritus
Democritus is responsible for theorising and naming the atom. "άτομο' is greek for atom. He theorised that there was something you couldn't physically cut. -
Jan 1, 1500
The classical elements
For hundreds of years, pre-existing any scientific equipment the elements were described as Water, Fire, Earth and Air. -
John Dalton
He believed that all matter was composed of atoms that were both invincible and invisible building blocks. He also published the idea that each element has a different mass. Also that atoms are indestructible and preserve their identities in all chemical reaction -
Antoine Lavoisier
He is known as the father of modern chemistry. He sparked the theory that an atom should be defined as a substance that could not be broken down. He is responsible for listing 23 elements. He dis this between 1777 - 1787. -
Joseph Proust
He Discoverd the law of definite proportions. Which details that aspects that substances only combine in very precise proportions. This sparked the idea that there were atom formations. -
Robert Bunsen
He was famous for the invention of the spectroscope and the bunsen burner. He found that each element produced a unique set of coloured bands called the spectroscope -
Dimitri Mendeleev
Known as the father of the periodic table he is responsible for dividing a table that had 62 elements at the time to what we now know as the periodic table. He could predict the atomic weight and density of elements that hadn't been discovered yet and left parts of the periodic table blank for them. -
JJ Thompson
He is responsible for finding that atoms consisted of negatively charged particles (now called electrons). This confirmed that atoms were not sold balls of matter. He is also the creator of 'Plum Pudding' -
Ernest Ruthford
Ruthford wanted to find out what was inside of atoms so he conducted an elaborate experiment in 1911 ('the ruthford model) that would shoot particles through a thin piece of gold. They mostly went through the piece of gold therefore proving atoms are mostly empty space. -
James Chadwick
He proved that neutrons have no charge and weight the same as a proton. Because atomic weight of an element is nearly double the atomic number and the atomic number is the number of protons in the atom ant there are usually the same number of neutrons as protons therefore the weight is double
