Atomic Theory

“All things are made up of atoms.”

States of matter

Solid, liquid, gas, and plasma

State of Solids

  • Has definite shape and volume
  • High density and not very compressible
  • Does not depend on the shape of the container (doesn’t fill it in)

State of Liquids

  • Has a fixed volume
  • Takes the shape of container
  • Less dense than solids
  • Almost incompressible

State of Gases

  • Takes the shape of the container
  • Takes the volume of container (this means that the gas molecules can be spread out evenly in the container or compressed in a smaller container. The volume is when the molecules are evenly distributed.)
  • Can be compressed
  • Gases are in the gaseous state at room temperature
  • Gases have more energy than liquids, and solids.
  • Gases are less dense.

State of Plasma

Plasma is simply an ionized gas, where the gas is charged with free electrons and positive ions because of the amount of energy plasma contains.

Unit 2.3 – Describe the various units used to measure pressure and conversions

There are several units that pressure is measured in.  The unit Pascal is the S.I unit is equivalent to 1 N per square metre. To compare the unit Pascal to Atmosphere pressure of Atm, 101.3 kPa is for 1 Atm. In addition, the unit Torr named after Torricelli is equivalent to the amount of mercury displaced by the mercury barometer of 760mm, therefore 760 Torr = 760mm of Hg.  For simplicity sake, all units can be compared to 1 Atmosphere, which is equivalent to 760 mm of Hg, 760 Torr, 101.3kPa, and 14.7 Psi.


Unit Compared to 1 atm Compared to 1 kPa
KPa 1 atm = 101.3 kPa
mmHg 1 atm = 760 mmHg 1 kPa = 7.501 mmHg
torr 1 atm = 760 torr 1 kPa = 7.501 torr
psi 1 atm = 14.7 psi 1 kPa = 0.145 psi
atm 1 kPa = 0.009869 atm

To convert an unit, since they are all proportional, use dimensional analysis to convert the units.

Converting 160kPa to all other units…


160kPa  = 1.58atm