The properties of matter and pure substances

 What are the properties of matter?

There are two general properties of matter. Mass is the amount of matter in an object. It can be measured in grams (g) and kilograms (kg). The mass of an object is always the same. The weight of an object depends on the effect of gravity. An astronaut always has the same mass but in space he will be weightless, because there is no gravity.

Volume is the amount of space an object occupies. The volume of solids is usually measured in cubic centimetres (cm3 ) or cubic metres (m3 ). The volume of liquids is usually measured in millilitres (ml) or litres (l). 1 ml = 1 cm3.

The specific properties of matter are qualities that differentiate types of matter. These properties are things like hardness, elasticity and density. Density is the relationship between the mass and the volume of an object. Different materials and substances have different densities. We use a formula to calculate the density of objects. Mass (m) Density (p) = Volume (V ) Density is measured in g/cm3 or in kg/m3 .

Hardness

Elasticity

Density

What are pure substances? 

Pure substances are found in nature. Each pure substance has specific properties that distinguish it from other substances. Pure substances are found as solids, liquids or gases. They change states when they are cooled or heated.

Gold is a shiny, metallic, yellow substance. It is solid at room temperature. It has a density of 19.3 g/cm3 . It becomes liquid at 1 064 ºC and as a liquid it has a density of 17.3 g/cm3 . It boils and evaporates at 2 850 ºC

Pure water is a liquid. It has no colour, taste or smell. It becomes solid (ice) at 0 ºC. It boils at 100 ºC and becomes a gas (water vapour). It has a density of 1 g/cm3 at 4 ºC. It has a density of 0.9 g/cm3 when it is solid.

Nitrogen has no colour or smell. It is a gas at room temperature. It becomes a transparent liquid at -196 ºC. It has a density of 0.81 g/cm3 when it is a liquid. It becomes a colourless solid at -210 ºC. It has a density of 0.3 g/cm3 when it is solid.