Properties of Matter Lesson 7

Properties that Define Matter Substances are defined by their Properties. A different word for properties is characteristics. You use physical properties when you describe a friend. For example you may talk about the person’s hair colour, eye colour, and height.

Observations are pieces of information we collect as we use our senses of sight, touch, hearing taste and smell. We will never use TASTE in the lab. Observations can be made using several senses. Sight, Smell, Touch, Taste and hearing.

What is a physical property? A characteristic or description of a substance that may help to identify it. Physical properties observed by the senses are in the following table ColourTextureOdourClarityTaste Colourless, white, black Fine, course, smooth, gritty Odourless, spicy, sharp, burnt, Clear, cloudy, opaque Sweet, sour, salty, buttery

Using observations is important in science and daily life. Automobile mechanics SEE a car’s oil level HEAR how the engine is running SMELL what is happening in the engine compartment

Qualitative properties Qualitative properties describe how something appears, sounds, or smells. A qualitative property might also explain how flammable or reactive a substance is.

Qualitative properties are useful for some things, but not for others. People such as Engineers must know the exact properties of the materials they use. Imagine if an engineer made a bridge of steel that was not strong enough, or a laptop computer out of plastic that melted when the computer heated up!

Quantitative properties Quantitative properties use numbers to record exact measurements. “Quantity” refers to a number and a unit such as 25 mL

Properties of matter Properties of Matter Qualitative Properties Example: The liquid is warm Quantitative Properties Example: The liquid is a 45 ° C

Physical Properties -A physical property describes a characteristic of a substance that can be observed or measured without changing the composition of matter. Example: Melting Point, Boiling Point

When water freezes it expands due to a special bonding between water molecules. Larger volume with the same mass = Less dense This is why ice floats

Observing Physical Properties PropertyDescriptionExamples What it looks like Colour and lustre The light the substance reflects gives it colour and lustre (shine) The names for some substances, such as gold, are also the names of colours. Gold has lustre; concrete is dull

Observing Physical Properties PropertyDescriptionExamples What it looks like Conductivity Conductivity is the ability of a substance to conduct electricity or heat. A substance that conducts electricity or heat is called a conductor. A substance with little or no conductivity is an insulator. Most metals are good conductors. Copper is a very good conductor of electricity and so is used to make electric wires. Styrofoam® and glass are insulators.

PropertyDescriptionExamples What it looks like Density Density is the amount of mass in a given volume of a substance. D = m/v The density of pure water is 1 g/mL. The density of gold is 19 g/mL. Water is denser than oil, but gold is denser than water.

Observing Physical Properties PropertyDescriptionExamples What it looks like Ductility Any solid that can be stretched into a long wire is said to be ductile. Copper is a common example of a ductile material.

Observing Physical Properties Property DescriptionExamples What it looks like Hardness Hardness is a substance’s ability to resist being scratched. Hardness is usually measured on the Mohs hardness scale from 1 to 10. The mineral talc is the softest substance on the Mohs hardness scale (1). Emerald is quite hard (7.5). Diamond is the hardest (10).

Observing Physical Properties PropertyDescriptionExamples What it looks like Malleability A substance that can be pounded or rolled into sheets is said to be malleable. Aluminum foil is an example of a malleable substance. Metals such as gold and tin are also malleable.

Observing Physical Properties PropertyDescriptionExamples What it looks like Viscosity Viscosity is the resistance of a fluid to flow. Honey has a high viscosity Compared to water.

Practical applications The Viscosity of oil keeps engines running. The numbers on containers of engine oil give the oil’s viscosity. Ideally, oil should be thin enough to flow easily when an engine is cold. But it needs to remain thick enough to protect an engine when it is hot.

Thicker oils can handle higher temperatures before the oil is chemically broken down and does not function properly.

The lower the number, the thinner the oil and the easier it flows. You need thin oil in the winter during cold temperatures because the oil still needs to be able to flow when the engine is cold. Many cars use multi grade oil. These oils are effective over a wide range of temperatures.

Physical Properties - Lab