Summary Chemistry Notes

STATES OF MATTER
Melting

 Melting is when a solid changes into a liquid
 Requires heat energy which transforms into kinetic energy, allowing the
particles to move
 Occurs at a specific temperature known as the melting point (m.p.) which
is unique to each pure solid

Boiling

 Boiling is when a liquid changes into a gas
 Requires heat which causes bubbles of gas to form below the surface of
a liquid, allowing for liquid particles to escape from the surface and within
the liquid
 Occurs at a specific temperature known as the boiling point (b.p.) which
is unique to each pure liquid

Freezing

 Freezing is when a liquid changes into a solid
 This is the reverse of melting and occurs at exactly
the same temperature as melting, hence the melting point and freezing
point of a pure substance are the same. Water for example freezes and
melts at 0ºC
 Requires a significant decrease in temperature (or loss of thermal energy)
and occurs at a specific temperature which is unique for each pure
substance

Evaporation

 When a liquid changes into a gas. Evaporation occurs only at
the surface of liquids where high energy particles can escape from the
liquid’s surface at low temperatures, below the b.p. of the liquid