Atomic Theory
the idea that everything is made of small particles
atomic theory
Using the gold foil experiment, he discovered the nucleus and protons. He also discovered that an atom was made mostly of empty space, and most of its mass is in the nucleus.
Ernest Rutherford
a chart of elements arranged into rows and columns according to their physical and chemical properties
Periodic Table
anything that has mass and takes up space
matter
A particle in the space outside the nucleus of an atom that has a negative charge.
electron
He believed that matter could be cut into smaller pieces to a certain point. He called these tiny particles atoms.
Democritus
He discovered that the nucleus contains neutrons
James Chadwick
Pure substances that are made up of only one type of atom
Elements
These are not considered matter because you cannot see them and they are forms of energy
light and heat
A particle in the nucleus of an atom that has no electric charge
neutron
He believed that matter was made of fire, water, air and earth
Aristotle
He proposed that electrons move in a circular orbits around the nucleus
Niels Bohr
He developed the first periodic table
Dmitri Mendeleev
the basic unit from which all matter is made
atom
A particle in the nucleus of an atom that has a positive charge
proton
He believed that Democritus was correct and matter was made of atoms.
John Dalton
Each element has a ________ that contains one or two letters.
symbol
Uses electrons instead of light particles to examine an atom
electron microscope
The center of the atom
nucleus
Using a cathode ray tube, he discovered electrons
J.J. Thomson
The number of protons in an atom
atomic number
empty space
The nucleus of an atom contains most of an atom's ___________.
mass