Matter/Chemical Change - Section 2 Flashcards
What is the smallest unit of matter?
Atom
What are the points of the Atomic Theory?
All matter is made up of atoms
Atoms of one element are different from atoms of another element
Atoms may combine with other atoms to form larger particles called molecules
Atoms cannot be created or destroyed by ordinary chemical means
What are atoms?
The smallest independent particles of an element that can exist in nature
Atoms are made up of three ________ _________
Subatomic particles
What is a proton?
Positive charge, found in the nucleus, approximately half the mass of the atom
What is a neutron?
Neutral charge, found in the nucleus, approximately half the mass of the atom
What is an electron?
Negative charge, found orbiting the nucleus, very little mass
In an atom, the number of __________ must equal the number of ____________
Protons, electrons
Describe John Dalton’s atom model.
Billiard ball model - he thought the atoms as tiny spheres
Describe JJ Thomson’s atom model.
Raisin bun model - he thought of the atom as a positively charged sphere with negatively charged electrons embedded within it
Describe Hantaro Nagaoka’s atom model.
Solar system or Saturn ring model - negatively charged electrons orbiting around the large positive charge
Describe Ernest Rutherford’s atom model.
Planetary model - negatively charged electrons orbit around the positively charged nucleus
Describe Niels Bohr’s atom model.
Electron shell model - the electrons orbit around the nucleus in specific shells
Describe James Chadwick’s atom model.
His model is identical to Bohr’s but the nucleus is shown to have neutrons along with the protons
What did John Dalton discover about the atom?
He was the first to define an element as a pure substance containing no other substances