History of Atom
Terms in this set (15)
smallest part of an element that keeps the element's properties
Greek philosopher that believed atoms were the smallest piece of matter
English chemist who developed the Atomic Theory
philosopher that stated all matter is composed of 4 elements - air, earth, water, and matter
proposed by John Dalton
1. All elements are composed of atoms that are indivisible and indestructible (not true because protons, neutrons and electrons were discovered)
2. Atoms of the same element are exactly alike (not true because of isotopes)
3. Atoms of different elements are different.
4. Compounds are formed by the joining of atoms of 2 or more elements.
- scientist who discovered the electron (negatively charged subatomic particle) using a cathode ray tube
- developed plum pudding model
Plum Pudding model
-a model of the atom created by JJ Thomson
- consists of electrons on the surface of a positively charged sphere
discovered the nucleus by shooting alpha particles through a thin piece of gold foil
cathode tube experiment
experiment done by JJ Thomson in which he discovered the electron
Gold foil experiment
an experiment performed by Rutherford that provided evidence that atoms are mostly empty space and have a dense, positive nucleus
scientist proposed a model of atom based on energy levels (Each energy level has a different amount of energy; the farther away an electron is from the nucleus, the more energy it has)
discovered the neutron
- model of atom where electrons move in definite paths (orbits) around the nucleus.
Modern Atomic Theory (Model)
model proposed by Schrondinger that says there is 90% probability of finding an electron in a certain area around the nucleus.
shows a dense nucleus with protons surrounding the center