1.3: Physical and Chemical Properties

Physical property

A characteristic of matter that is not associated with a change in its chemical composition.

Physical change:

A change in the state or properties of matter without any accompanying change in the chemical identities of the substances contained in the matter.

Chemical property:

The ability to change from one type of matter into another (or the inability to change).

Chemical change:

Always produces one or more types of matter that differ from the matter present before the change.

Extensive property:

A property that depends on the amount of matter present.

Intensive property:

A property of a sample of matter that does not depend on the amount of matter present.

Examples of physical properties

Density, color, hardness, melting point, boiling point, and electrical conductivity.

Examples of physical changes:

Wax melting, sugar dissolving in coffee, steam condensing into liquid water, magnetizing/demagnetizing metals, and grinding solids into powders.

How to identify a physical change: The substance's physical state, form, or properties change, but its chemical composition does not.

Examples of chemical properties:

Flammability, toxicity, acidity, and reactivity

Examples of chemical changes:

Rust forming, nitroglycerin exploding, combustion (burning), copper reacting with nitric acid, cooking food, digesting food, and rotting food.

How to identify a chemical change: One or more new types of matter are produced.

Examples of extensive properties

Mass, volume, and heat.

Examples of intensive properties:

Temperature

NFPA 704 Hazard Diamond

Blue — Health: Indicates the level of health hazard.

Red — Flammability: Indicates the level of fire hazard.

Yellow — Reactivity: Indicates how readily the substance will undergo detonation or a violent chemical change.

White — Special hazards: Indicates special hazards such as being an oxidizer, reacting dangerously with water, being corrosive, acidic, alkaline, biological, radioactive, and so on.

Hazard scale: Each hazard is rated from 0 to 4, with 0 being no hazard and 4 being extremely hazardous.

Metals

Elements that conduct heat and electricity well.

Nonmetals

Elements that conduct heat and electricity poorly.

Metalloids

Elements that have intermediate conductivities.

Periodic table

A table of elements that places elements with similar properties close together.