Matter

Matter is anything that has mass and volume

A pure substance has an invariant chemical composition and distinct properties.

A pure substance can exist as an element (e.g ) or a compound (e.g ). A compound can only be separated by chemical methods.

A mixture consists of two or more pure substances that retain their individual identities and can be separated by physical methods.

A mixture can be homo or heterogeneous

• Homogeneous (solution): the mixture has uniform composition and properties throughout
  • E.g Air, made from nitrogen and oxygen
• Heterogeneous (mechanical mixture): the mixture is not uniform
  • E.g oil and water, salad dressing

A chemical property can only be observed when one kind of matter is converted into another, i.e how it reacts with another substance

• Flammability
• Toxicity
• Heat of combustion
• pH value
• reactivity

A physical property can only be observed without changing one kind of matter into another

• State (solid, liquid, gas)
• Colour
• Density
• Malleability