-
8000 BCE
Stone Age
Cavemen thought that matter was anything that was solid that stone tools could be made out of. -
6000 BCE
The Earliest Chemists
The earliest chemists they produced and sold valuable metals such as gold, silver, and cooper. -
1200 BCE
The Iron Age
Iron was combined with carbon to make steel for stronger tools. It was also in this time period that people first discovered how to extract iron from rocks and melt it into pots and pans. -
500 BCE
The Greek Philosopher named Democritus
Democritus believed that all matter could be divided into tiny, indivisible bits called “atoms” -
Lavoisier's Work
Antoine Lavoisier, he developed a system that was used for naming elements. He even named oxygen and hydrogen. He is also considered one of the very first people to name sulfur as a element and not a compound. -
Dalton's Theory
Dalton's theory he proposed was the indivisible unit of an element is the atom. -
Thomson's Theory
He believed and discovered that electrons resided within a spherical of uniform positive change. This theory is also known as the Plum Pudding Model -
Nagaoka's Theory
Hantaro Nagaoka's theory was that a alternative model of the atom where a positively charged center is surrounded by a great number of electrons that are revolving. -
Rutherford's Discovery
Rutherford demonstrated that the existence of a positively charged nucleus that contains almost all of the mass of the atom. -
Bohr's Theory
He proposed that fixed orbits in the form of a circle, orbits around the nucleus for electrons. -
Chadwick's Theory
James Chadwick's atomic theory was that he discovered beryllium atoms with alpha particles. It caused an unknown radiation. This became the neutron. -
Today's Model
In the current model that we use today, electrons take up space(orbitals) around the nucleus determined by their energies
