-
Joseph Proust-Law of Constant Composition
The law declared that the composition of a substance is always the same, no matter where it was found or how it was made. He studied different sources of many compounds. He found that they always contained the same ratio by weight of their elements. He used table salt as an example contained 1.5 times as much chlorine as sodium. He also found that water always contained 8 times as much oxygen as hydrogen.
conclusion-the ratio by mass of the elements in a chemical compound is always the same -
John Dalton-modern atomic theory
no experimentation used laws to develop theory
conclusion- matters are made of atoms that are identical atoms that cannot be destroyed or rearranged in reaction
contribution-the modern atomic theory -
Joseph John Thomson- charge/mass of the electrons
Founder of electrons and used cathode ray tubes to to find out the charge to mass ratio of an electron to be 1.759 x 108 coulombs/ gram. He also dicovered canal rays were related with a proton. Helped with the understanding of atom- Electrons have a charge to mass ratio of 1.759 x 108 coulombs/ gram. thomosno had a huntch that the rays had let off from the electron gun which were inseparable from the latent charge, and decided to try and prove this by using a magnetic field. -
Joseph John Thomson- leptons
Leptons are a family of elemental particles that includes the electron, the muon, the tau, and their associated neutrinos. Such as quark, make up protons and neutrons in the nucleus. Its a fermion, meaning it has a quantum spin of ½.
conclusion- discovered the leptons and its relationships with the atoms.
contribution-leptons -
Ernest Rutherford-positively charged nucleus
Gold foil experiment- shot a small positively charged particals were directed at a thin foil of gold atoms
conclusion-the center of the atom is positive, atoms also contain empty spaces
contribution-figured elctrons grouped around the nucleus -
neils bohr- enregy levels
explained that electrons travel around the nucleus in exact paths. These paths are always at a certain level away from the nucleus. He also stated that electrons cannot travel in between each path, but they can hop from one path to another.
contribution- energy levels -
Ernest Rutherford-charge and mass of the proton.
While experimenting with nitrogen gas with alpha particles, he spotted a particle with properties identical to a hydrogen nucleus.He continued to study more into hydrogen atom contamination. he came up with nitrogen atom broke down under great force of the collision and the particle released was a constituent part of the nitrogen atom nucleus.
conclusion- dicovered the proton
contribution- discovered the proton -
Ernest Rutherford-composition of electricity
When there are more than two electrons in an atom, they move around the nucleus in different orbits are known as shells. The inner shell contain electrons, known as bound electrons. there are - + elctrons that flow around the electrical current he anaylised its flow through the connector until an electiral aharge was present
conclusion- analysised how the compositon works.
contribution- composition of electricity -
James Chadwick-neutral neutrons
experiment- tried to simplify as much as possible the particles, performed radiation
conclusion- particles had no electric charge, showig they were neutral particles
contribution- concluded that particles of a beam from alpha particles hitting beryllium carried no electric charge they were neutral particles called neutrons -
Murray Gell-Mann- Quarks
proposed the existence of a new level of elementary particles - quarks. These little bits of matter which when used kind of as building blocks of protons and neutrons, helped explain some complex chemical substances.
contribution-helped to lay the base for our understanding of the components that make up matter
