What are the subdivisions of matter?
Pure substances & mixtures
What are the types of ‘pure substances’
Elements & compounds
Definition of an ‘element’ (pure substances)
Pure substances that contain only one type of material
Examples: Lead or Aluminum
Definition of a ‘compound’ (pure substances)
Two or more elements in a definite ratio
Example: H₂O
Definition of a ‘homogenous mixture’
A mixture where the composition is uniform throughout the sample and the different parts of the mixture aren’t visible.
Definition of a ‘heterogeneous mixture’
A mixture where the composition varies from one part of the mixture to another and where the different parts of the mixture are visible.
Definition of physical change vs chemical change
Physical changes occur when matter undergoes a physical change of state, but its composition remains constant. Chemical changes occur when the original substance is converted to a new substance with different physical and chemical properties.
Volume SI unit
cubic meter (m³)
Length SI unit
meter (m)
Mass SI unit
kilogram (kg)
Temperature SI unit
kelvin (K)
Time SI unit
seconds (s)
Density SI unit
g/ml³
People to know
J.J. Thomson
Ernest Rutherford
What did J.J. Thomson do?
Discovered cathode rays – invented the plum pudding model
What did Ernest Rutherford do?
Discovered the small region of positive charge in an atom (the nucleus), and that the space around it was occupied by electrons.
How to find atom # (and vice versa)
The # of protons
How to solve for atomic mass
Protons + neutrons
How to solve for ionic charge
Protons - electrons
Definition of isotopes
Atoms of the same element that have different mass numbers
How to calculate atomic mass
Mass of isotope 1 x 0.% abundance
Mass of isotope 2 x 0.% abundance
Different models to know
Dalton’s atomic model, Thomson’s Plum Pudding Model, Rutherford & Bohr’s Atomic Model, and the Orbital Model
Dalton’s Atomic Model
All elements are composed of extremely small particles called atoms.
Thomson’s Plum Pudding Model
Atoms are positive spheres with negative electrons embedded throughout.
