Lets get Physical Physical as in Science Have

Let’s get Physical, Physical – as in Science! Have you ever played twenty questions?

A little Science Humor What does this have to do with Physical properties? • Two fish swim by a fisherman’s baited hook. One fish says t the other, “You know, I never could figure out why those worms always go swimming with lead weights tied around their necks. ” • The other fish replies, “Yeah, they must be pretty dense. ”

Physical Properties • One that can be observed or measured without changing the matter’s identity. • Examples include magnetism, the conducting of electricity, strength, flexibility, color, odor, mass, volume, etc.

More Physical Properties • Thermal Conductivity – the rate at which a substance transfers heat • State – the physical form a substance is in • Solubility – the ability of a substance to dissolve in another substance • Ductility – the ability of a metal to be pulled in a wire • Malleability – the ability of a substance to be rolled or pounded into thin sheets

Question Time • 1. A property that be observed or measured without changing the substance is a a. chemical property b. magnetic property c. physical property • 2. The ability of an object to be rolled into sheets is a. ductility b. malleability c. solubility d. state • 3. The ability of a substance to dissolve in a liquid is a. malleability b. ductility c. solubility d. thermal conductivity • 4. The ability of a substance to be drawn into a wire is a. ductility b. malleability c. solubility d. state • 5. The rate at which a substance transfers heat is a. state b. solubility c. thermal conductivity d. malleability • 6. The physical form that matter is in is a. state b. thermal conductivity c. malleability d. solubility

How do we Identify Matter? • We use physical properties every day to do it. • Are your socks clean? Do they smell? • Does your shirt match your pants? • Does your science book fit into your backpack? • How does a Vending Machine work?

Density • The amount of matter in a give amount of space or volume • Different liquids can form separate layers if they are of a different density. • What would you rather carry around – a kg of feathers or a kg of lead? • Knowing the volume that these objects take up might help you decide

It’s time to play “Will it Sink or Will it Float? ” • Let’s try to predict whether these items will sink or float? Are we as good as David Letterman? • An egg, an orange, a can of pop, a ½ pint of milk, a can of diet pop • What else would you like to try?

Using Density to Identify Substances • To find density – you take mass divided by volume • Some substances are easy are identify by density • Water has a density of 1 g/ml • Lead is 11. 35 g/ml while mercury is 13. 55 g/ml • What is the density of an object whose mass is 25 kg and has a volume of 10 ml? • 2. 5 g/ml • What is the mass of a 15 ml sample of mercury? • D x V = M (203 grams)

Does a Physical change create a new substance? Physical changes affect one or more of the physical properties of a substance. Examples include Freezing water to make ice cubes; sugar dissolving in water, melting butter, molding a lump of clay Physical changes do not change the identity of the matter involved.

Question Time • 1. Density is a. mass x volume b. mass – volume c. mass divided by volume d. mass + volume • 2. T or F – Physical changes create new substances.

Summary of Physical Properties • Physical properties of matter can be observed without changing the identity of the matter. • Examples of physical properties include conductivity, solubility, malleability, ductility, density, state, etc. • Density is the amount of matter in a given space. • Scientists like to use density because it is always the same at a given temperature and pressure • Substances undergoing physical changes are still the same substance. • Examples of physical changes are freezing, bending, melting, dissolving, and cutting.