paulpaul Flashcards
They determine the element’s identity
Proton
They contribute to the atom’s mass and stability
Neutron
They occupy specific energy levels or shells.
Electrons
460 BC - Greek philosopher proposes the existence of the atom
Democritus
He pounded materials until he made them into smaller and smaller parts
Democritus
He called them _____ which is Greek for “_____”.
He called them atomos which is Greek for “indivisible”.
1803 - British chemist; elements combine in specific proportions to form compounds
John dalton
Solid Sphere Model or Bowling Ball Model
Proposed by John Dalton
All substances are made of atoms that cannot be ____, _____, or ____.
Atoms join with _____.
Atoms of the same element are _______, and atoms of different elements are ________.
created, divided, destroyed
other atoms to make new substances.
exactly alike, different in mass and size.
JOHN DALTON
1897 - English chemist and physicist; discovered 1st subatomic particles
JJ Thompson
Plum Pudding Model or Raisin Bun Model
Proposed by J.J. Thomson
Atoms contain negatively charged particles called electrons and positively charged matter called protons.
Created a model to describe the atom as a sphere filled with positive matter with negative particles mixed in
Jj thomson
1912 - New Zealand physicist discovered the nucleus
Ernest Rutherford
Nuclear Model
Proposed by Ernest Rutherford
Small, dense, positively charged particle present in ______ called a ___
_____ travel around the _____, but their exact places cannot be described.
nucleus, proton
electron, nucleus
Ernest rutherford
Gold foil experiment
Ernest rutherford
1913 - Danish physicist; discovered energy levels
Neil’s Bohr
Planetary model
Niels bohr
_____ travel around the nucleus in definite paths and fixed distances.
_____ can jump from one level to a path in another level.
Electrons
NIELS BOHR
1924 - Austrian physicist; developed the electron cloud model
Erwin Schrodinger
Electron Cloud Model
Proposed by Erwin Schrodinger
The exact path of ____ cannot be predicted.
The region referred to as the ______, is an area where electrons can likely be found.
Electrons
Electron cloud
Erwin Schrödinger
1932 - English physicist; discovered neutrons
James Chadwick
_____ have no electrical charge.
Neutrons have a mass nearly equal to the mass of a _____.
Unit of measurement for subatomic particles is the atomic mass unit (____ )
Neutrons
Proton
Amu