Physical and Chemical Properties

All substances have properties… Including people! Example: People can be identified by their … Face (shape, expressions) Voice Height Finger prints Eye color Hair color Teeth DNA

What are properties? Matter has observable and measurable qualities. We can use general properties to identify substances. Two basic types of properties of matter: Physical properties and Chemical properties:

Physical Properties Physical properties are used to identify, describe and classify matter. Characteristic of a substance that can be observed (using your senses) without changing the substance into something else. State Colour Odour Taste Texture Melting point Boiling point Density

Physical Properties Physical properties can be classified as qualitative or quantitative.

Physical Properties Qualitative properties describe matter using words. They cannot be measured or expressed numerically (no numbers involved). ex. water is colourless, odourless

Physical Properties Quantitative properties can be measured and expressed numerically (numbers are involved). ex. the melting point of water is 0°C

Chemical Properties Chemical properties describe how a substance reacts with another substance to form a new substance Flammability Rusting Reactivity with metals Reactivity with oxygen Reactivity with water Reactivity with acids

Physical & Chemical Change

Physical & Chemical Change

Physical Changes do not produce new substances (it’s still the same substance with same properties) involve only one substance (except dissolving) are changes in form (powder, crystal, cubes, granular) or state (solid, liquid, or gas) most are easily reversible

Examples of Physical Changes: Changes of state (boiling, melting, freezing, condensation, sublimation) Dissolving (ex. Dissolving sugar in water - the sugar particles spread out, but they are still there, as sugar particles.)

Chemical Changes always produce a new substance which has different properties from the starting substance(s) involve more than one substance many are not reversible

Examples of Chemical Changes: Burning paper (the gases and black substance formed are new substances, and cannot be reversed back to paper) Rusting nails (rust formed is a new substance, formed from the metal and oxygen)  

How can we tell if a chemical change has occurred? Look for clues that a new substance has formed

Clues that indicate that a new substance has formed in a chemical reaction are; colour change (not a blending of the initial colours) gas (bubbles) is produced (not from boiling) a solid (precipitate) is formed when two solutions are mixed together energy is released (usually heat or light) or absorbed (substance feels colder), but not because of heating with a burner or cooling with ice etc. odour change / new odour

Physical or Chemical Change?

Physical or Chemical Change?

Physical or Chemical Change?

Physical or Chemical Change?

Physical or Chemical Change?

Physical or Chemical Change?