Basic chemistry help for students and teachers

 

Interactive Chemistry Worksheets for Students

 

Periodic table

Naming compounds

Basic formula

Simple compounds

Ionic compounds 1

Ionic compounds 2

Chemical suffixes

Old chemical names

Hydrocarbons - Alkanes

Alkanes, alkenes & alkynes

Alkanols to alkanoic acids

 

Common compounds

Common formula quiz

Acids, bases and salts

Covalent compounds

Printable worksheets
 

 

 

What is a physical change?

Matter exists in one of three physical states - solid, liquid or gas.

In a physical change matter changes state from one physical state to another.

For example when an ice cube melts it changes from the solid state to the liquid state.

Physical changes are easily reversible. In the melted ice cube is put back into the freezer it will change back into a solid.

Key points:

  • Matter exists in three physical states - solid, liquid and gas.
  • Matter can change from one physical state to another.
  • The physical changes of state are easily reversible
  • Energy is absorbed or given off during physical changes of state.

What are the physical changes of matter?

  • A solid changing to a liquid it is called melting or fusion.
  • A liquid changing to a gas is called evaporation.
  • A gas changing to a liquid is called condensation.
  • A liquid changing to a solid is called solidification or freezing.
  • A solid changing to a gas is called sublimation.  

Examples of physical changes.

Physical change Example
 Sublimation Dry ice change from a solid to a liquid
 Melting or fusion  An ice cube melting
 Condensation  The formation of dew on grass in the morning
 Evaporation  A puddle disappearing on a hot day
 Solidification or freezing  The formation of hail stones