Characteristic Properties

A characteristic property helps you identify a substance. Out of all the elements, only copper melts at 1083 oC. Out of all common compounds, only H2O has, at a specific temperature, a density of 0.98g/ml (usually rounded to 1). To say that I have 215 g of a substance in my pocket will not help you guess what it is. It may be a diamond, tangerine peels or a bunch of Kleenex. So mass is not characteristic.

Here is a list of physical properties that are characteristic:

        Density

        Melting or freezing point

        Boiling point

        Electrical conductivity, if expressed as a certain number

        Refractive index ( though Iíve never seen them use this one on provincial exams)

Here is a list of chemical properties that are characteristic for certain substances. Know all of them.

TEST

RESULT

INDICATES PRESENCE OF:

Cobalt chloride

Turns from blue to pink

Water = H2O

Glowing splint

Bursts into flames

Oxygen gas = O2

Limewater

Turns cloudy because of CaCO3

Carbon dioxide gas = CO2

Flaming splint

Popping sound and only water is left behind

Hydrogen = H2

 Properties also help distinguish groups of elements or compounds from other groups. Such a property is known as a group characteristic property. Here are some examples, many of which will be seen again later in the course, so you don't have to learn the specifics yet, but understand the general idea.

Group

Group Characteristic Properties

alkali metals

Soft, low-melting metals

acids

Conduct electricity (electrolytes) and turn blue litmus red

bases

Conduct electricity (electrolytes) and turn red litmus blue