the smallest piece of an element that still represents that element
atom
a particle with one negative charge
electron
most of an atoms mass and positive charge is concentrated in a small area in the center of the atom
nucleus
an atomic particle that has one positive charge
proton
a neutral particle that exists in the nucleus of an atom
neutron
an area around an atomic nucleus where an electron is most likely to be located.
electron cloud
believed that matter is made of small, solid objects that cannot be divided, created, or destroyed.
Democritus
believed that all matter is made up of fire, air, water, and earth.
Aristotle
proposed the atomic theory
Dalton
1981 invention of a high-powered microscope
STM
Made the cathode ray tube
Thompson
created the gold foil experiment
Rutherford
dense and positively charged particles
alpha particles
discovered that the nucleus also had neutrons
Chadwick
studied hydrogen atoms because they contain only one electron
Bohr
protons and neutrons are made up of this
quarks
a group of particles
leptons
gluons and photons are examples of
bosons
periodic symbol H
hydrogen
periodic symbol He
helium