Atomic Structure ppl

Atom

The smallest particle of an element that retains the properties of that element mostly empty space

Democritus

proposed that matter was composed of tiny indivisible particles called Atomos

Aristotle

Aristotle rejected democritus and believed that matter could be endlessly divided

Lavoisier

came up with the law of conservation of mass determined that mass cannot be created nor destroyed it is only conserved or transferred

Proust

came up with the law of definite proportions, which says a compound always has the same relative amounts of elements that compose it

Dalton

first person to describe an atom, his model was called the Billard ball model(1st), he said that an atom is a uniform solid sphere, he developed four atomic theories to describe the atom

Thomson

discovered the electron using cathode ray expiremnt, he determined that the electron had a negative charge cause it was attracted to the positive magnet and opposites attract, made the plum pudding model, came up with the newer model of the atom

Cathode ray experiment

showed that atoms have tiny, negatively charged particles called electrons.

He used a glass tube with electricity running through it and saw a glowing beam that bent toward a positive plate, proving the particles were negative.

This experiment proved atoms are made of smaller parts

electron

first subatomic particle discovered, negatively charged, makes up the atoms volume (how big atom is) has nothing to do with the mass

plum pudding model

Thomson, 2nd model, electrons we like plums embedded into a positive charge pudding

Milikan

he determined the mass of the electron using the oil drop experiment

Goldstein

discovers the proton

Proton

positively charged subatomic particle, makes up ½ of the atoms mass, located in the nucleus

Becquerel

discovered radioactivity (spontaneous emission of radiation from the nucleus) by accident, 3 types of radioactivity = Alpha(+), Beta(-), Gamma(N)

Rutherford

student of thomson, discovered the nucleus,

determined that the nucleus is a small dense positively charged region in the center of the atom, and it contains all of the atoms mass surrounded by electrons

Used the Gold Foil expirment to prove theory

didn’t determine the neutral charges

Gold foil expirment

Rutherford, fired alpha particles(+) at a piece of gold foil, after firing alpha particles one particle hit the nucleus and reflected

Nucleus

central core of the atom, composed of protons and neutrons, changed the model of the atom

Chadwick

discovered the neutron

neutron

chadwick, a neutral subatomic particle found in the nucleus and makes of ½ of the atoms mass, mass of atom is found in the nucleus and composed of protons and neutrons (how heavy)

Bohr

says that electrons travel in orbits in different energy levels around the nucleus, he explained why electrons don’t get pulled into the nucleus, his model of atom is called Planetary Atom (3rd)

De Broglie

said that matter could be like a wave, said particles like the electron could now have properties of both waves and particles

current model of the atom

quantum mechanical or electron cloud model

Heisenberg

heisenberg uncertainty principle: it is impossible to know exactly the position and velocity(momentum) of a particle, the better we know one the less we know the other, the more precisely the velocity is measured the less precise the position (vise versa)

schrödinger

developed current model of atom, model is based off of mathematical solutions, model told us that electrons are traveling in orbitals not orbits around the nucleus, model told us the atom has two regions, the nucleus and the electron cloud

quark

protons and neutrons can still be broken down into a smaller particle called the quark