kinetic particle model of matter

2.1.1 | states of matter

matter

matter exists in three states: solids, liquids, and gases. their differences come from particle arrangement and movement.

2.1.2 | particle model

all matter is made of tiny particles that are constantly moving. their arrangement, separation and motion explain the properties of solids, liquids and gases.

particle arrangement and motion

• solids: particles closely packed in a regular pattern, vibrate in place
• liquids: particles close together but can slide past each other
• gases: particles far apart, move freely and quickly
• simple particle diagrams can represent these states.

temperature and kinetic energy

temperature is a measure of the average kinetic energy of particles in a substance. as temperature increases, particle motion becomes more vigorous. absolute zero is the lowest possible temperature, where particles have minima kinetic energy.

gas pressure

gas pressure is caused by particles colliding with the walls of their container. increasing temperature or reducing volume increases pressure, as particles move faster and collide more often.

brownian motion

brownian motion is the random movement of particles suspended in a fluid (liquid or gas) due to collisions with fast-moving molecules. it provides evidence for the kinetic particle model. a larger particle like a pollen grain is constantly bombarded by smaller particles like water molecules, causing random motion in fluids.

forces and properties

• strong forces: solids
• weaker forces: liquids
• very weak forces: gases
• collisions with fast-moving molecules can move microscopic particles

2.1.3 | gases and the absolute scale of temperature

gases can change their qualities based on changes in volume, temperature and pressure.

changes

at constant temperature:

• increase in volume: decrease in pressure
• increase in pressure: decrease in volume
• this conforms to boyle's law, defined by the equation p1v1 = p2v2, where p1 and v1 are initial pressure and volume, and p2 and v2 are final pressure and volume

at constant volume:

• increase in temperature: increase in pressure
  • this is because particles have greater kinetic energy, and so collide with the walls more frequently
• increase in pressure: increase in temperature

kelvin scale

the kelvin scale is an absolute temperature scale starting at absolute zero (0 k), where particles have minimum kinetic energy. to convert celsius to kelvin, add 273. at zero degrees kelvin, particles have zero kinetic energy