chapter 2 properties of matter. 2.1 properties of matter 2.1 classifying matter
TRANSCRIPT
Chapter 2
Properties of Matter
2.1 Properties of Matter 2.1 Classifying Matter
Pure Substances
Elements Compounds
Elements A substance that cannot be broken down
into simpler substances. Has a fixed composition because it contains
only one type of atom.
Compounds A substance that is made from two or more
simpler substances and can be broken down into those simpler substances.
Always contains two or more elements joined in a fixed proportion.
Compounds
Compounds Can be broken down into simpler
substances.
Mixtures
The properties of a mixture can vary because the composition of a mixture is not fixed.
2 kinds of Mixtures
Heterogeneous Homogeneous
Heterogeneous Mixture The parts of the mixture are noticeable
different from one another.
Homogeneous Mixture The substances are so evenly distributed
that it is difficult to distinguish one substance in the mixture from another.
Air is an homogenous mixture
Solutions, Suspensions, and Colloids
This is another way of classifying mixtures.
Based on the size of its largest particles.
Solution When substances dissolve and form a
homogeneous mixture.
Solutions The particles in a solution are too small to
settle out of the solution, be trapped by a filter, or scatter light.
Suspensions A heterogeneous mixture that separates
into layers over time
Suspensions Over time, the suspended particles will
settle to the bottom of the container.
Colloids Contains some particles that are
intermediate in size between the small particles in a solution and the larger particles in a suspension
2.2 Physical Properties
Any characteristic of a material that can be observed or measured with out changing the composition of the substances in the material.
Viscosity The tendency of a
liquid to keep from flowing, its resistance to flowing.
The greater the viscosity, the slower the liquid moves.
Conductivity A material’s ability to allow heat to flow. Metals have a high conductivity.
Malleability The ability of a solid to be hammered
without shattering. Most metals are malleable.
Hardness The resistance of a
material to scratching.
Melting and Boiling Point Melting: the
temperature at which a substance changes from solid to liquid.
Boiling: the temperature at which a substance changes from a liquid to a gas.
Melting and Boiling Point
Density The ratio of the mass of a substance to its
volume.
Mass: the amount of stuff something is made up of.
Volume How much space an object takes up.
Water displacement
Reading a Graduated Cylinder
Density tells you how tightly packed or loosely packed something is
Density also tells you if the particles in the substance are more like shot puts or ping pong balls
A bag or rocks is denser then a bag of styrofoam peanuts
When sacking groceries, where should the least dense items go?
What weighs more? A pound of feathers or a pound of lead?
Density Range Hydrogen gas:.000089 g/cm3
Osmium:22 g/cm3
Density of the Universe 5 × 10-30 g/cm3 or.000000000000000000000000000005 g/cm3
Gold is dense: 19.3 g/cm3
1 metric ton of gold = 1000 kg = 2200 lbs
Density Units = g/cm3 or g/ml Density tells you what the mass of the stuff
would be if you had a cubic centimeter of the stuff.
Density determines if something sinks or floats
Why is it easier to float in salt water?
Density of Air
Density of the Earth
Population Density
Population Density
Bone Density
10g 2 cm3
10g/2cm3
10g
2cm3
Show work? Label every Number!
=5 gcm3
Baggie #3
Baggie #2
Physical Properties
Physical properties are used to identify a material, to choose a material for a specific purpose or to separate the substances in a mixture.
Filtration
Chromatography
Distillation
Recognizing Physical Changes A physical change occurs when some of the
properties of a material change, but the substances in the material remain the same.
A phase change is a physical change.
2.3 Chemical Properties
Is any ability to produce a change in the composition of matter.
Chemical properties can be observed only when the substances in a sample of matter are changing into different substances.
Examples of Chemical Properties
Flammability is a material’s ability to burn in the presence of oxygen.
Examples of Chemical Properties
Reactivity is the property that describes how readily a substance combines chemically with other substances.
Recognizing Chemical Changes