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460
Greeks's B.C
Not until around 460 B.C., a Greek philosopher, Democritus, develop the idea of atoms. He asked this question "If you break a piece of matter in half, and then break it in half again, how many breaks will you have to make before you can break it no further?" possible bit of matter. He called these basic matter particles. -
John Dalton's Atomic Theory
Dalton's Atomic Theory is that all matter is made of atoms. Atoms are indivisible and indestructable. All atoms of a given element are identical in mass and properties. Compounds are formed by a combination of two or more different kinds of atoms. A chemical reaction is a rearrangement of atoms. -
Crook's CRT
Crookes developed the Crooks Tube, investigating cathode rays in his investigation in the conduction of the electricity in low pressure gases.He discovered that as the pressure was lowered, the negative electrode (cathode) appreared to emit rays.As these examples indicated, he was a pioneer in the construction in use of the vacuum tube. -
J.J Thompson electrons
J.J Thompson expiremented with Crooke's CRT.He stuck a magnet up to it,and the light repelled,he suck the other end,and the light came towards it.He had only one hypothesis.It was not light,it was negative particles,he called them, electrons. -
Rutherfords particle shooting
Rutherford decided to test shooting particles at a gold sheet.Some of them went through it,but then he noticed some of them would bounce back,he decided something is in there,he decided it was also positive.This is now known as the nucleus. -
Borh has an idea
Bohr decided to take a look at the particle shooting expirment.He worked on it,and found out that there was more to it, Bohr said the electrons are in orbits or energy levels around the nucleus.Electrons are in unpredictable motion,
