Physical and Chemical Properties How to describe a

Physical and Chemical Properties How to describe a substance

Physical Property • Anything that can be observed or measured without forming a new substance • Examples include: colour, texture, taste, smell, state, malleability and ductility “Describes what the substance looks like”

Name some physical properties of sodium Colour: Silver State: Solid Texture: Smooth Lustre: Shiny

Chemical Property • Describes how a substance reacts with another substance when forming a new substance “How a substance behaves when exposed to another substance”

Chemical Properties Ex: Combustibility (how it behaves when exposed to Oxygen) Reacts with water (how it behaves when it is placed in water)

Think About It! What physical and chemical properties do you see?

Physical and Chemical Properties of Sodium Physical Properties: Hardness: Soft Colour: Silver Chemical Properties: Very Reactive when exposed to water Not Reactive when exposed to oil

Quiz Is this describing a physical or chemical Property? a) The water froze and became a solid • Physical Property - State b) Metal rusted when it reacted with oxygen • Chemical Property – Slow reaction with oxygen c) The silver necklace is shiny • Physical Property - Lustre • Physical Property - Taste d) The sugar tastes sweet e) When magnesium and acid are combined they produce a new gas • Chemical Property – Magnesium reacts with acid

Types of Physical Properties • Qualitative - a property that can not be represented by numbers - a quality of a substance How can you describe yourself without numbers? - Ex: Hair Colour, Eye Colour, Smell, etc.

Types of Physical Properties • Quantitative - a property that can be represented by numbers How can you describe yourself using numbers? Ex: Height, Weight, Density, Shoe Size, etc.

Physical and Chemical Changes How can a substance change?

Physical Changes A physical change is a change in the form or state of a substance This includes: - Substance dissolving in another –Sugar dissolving in water - Change of state - Boiling, freezing, evaporating - Cutting into pieces

What happens to salt when you put it in water? Salt dissolves in water to create salt water

Is dissolving a physical or chemical change? • Can we get the salt back? • Has the salt and water changed into a new substance? Let’s see!

The Bolivian Salt Plains • What you get when salt water dries up • Salt is separated from the water

How do I know it’s a lake? • All of this is coral!

Chemical Changes • A chemical change is the formation of a new substance • Ex: Burning a piece of wood produces carbon dioxide and ash (carbon) – 2 new substances are formed

Clues for a Chemical Change 1) Colour change – brand new colour, not blue become less blue 2) Formation of a gas 3) Formation of a new odour 4) Formation of a precipitate (solid created from liquids) 5) Formation of light or a change in heat

Let’s take a look at some physical and chemical changes!!!