Solids, Liquids & Gases
Has a definite volume but not a definite shape
liquid
When a liquid is cooled it becomes what?
solid
Phase change of a solid turning into a liquid
melting
Anything that has mass and takes up space
matter
What happens to the particles of a substance when its temperature increases?
The particles move faster and spread out.
Has a definite shape and volume
solid
When heat is added to a liquid it becomes what?
gas
A phase change of a solid turning into a gas without passing through liquid state
sublimation
A group of atoms held together by chemical bonds
molecules
As a solid turns to a liquid, what happens to the thermal energy?
increases
In what state do molecules move extremely quickly and by bouncing off each other
gas
When a gas is cooled it becomes a what?
liquid
Change from a liquid to a solid
freezing
Evaporates easily; has a relatively high vapor pressure/low boiling point.
volatile
Why does increasing surface area (e.g., hanging clothes spread out) speed up evaporation?
More particles are at the surface and can escape; moving air removes humid air, maintaining a concentration gradient.
Rank compressibility of the three states and explain using the particle model.
Gas > liquid > solid
because particle spacing is largest in gases, smallest in solids.
What must happen for matter to change states?
it must gain or lose energy
Phase change of a gas turning into a liquid
condensation
The spreading/mixing of particles from higher to lower concentration due to random motion.
diffusion
What happens when an object's kinetic energy increases?
the particles move faster
Why do gases have no definite volume or shape, while solids do?
Gas particles move freely and occupy all available space; solids have fixed positions and strong forces holding particles in place.
During boiling, the temperature stays constant even with continued heating. Why does the temperature doesn't go up?
because the energy is used to break intermolecular forces, so it doesn't increase the temperature anymore
Water boils at a lower temperature on a high mountain. Explain.
Atmospheric pressure is lower; boiling occurs when vapor pressure = external pressure, so it happens at a lower temperature.
The temperature at which a solid changes to a liquid at a fixed pressure
melting point
Why does a sealed Aerosol Can left in the sun be dangerous? Use the particle model.
Heating increases particle kinetic energy → more frequent/forceful wall collisions → pressure rises and can exceed the can’s strength.