Science Exam Notes
Chemistry

Particle Theory of Matter:
 Particle Theory of Matter: A theory that describes the composition and behaviour of matter.
 All matter is made up of tiny particles that have empty spaces between them.
 Different substances are made up of different kinds of particles.
 Particles are in constant random motion.
 The particles of a substance move faster as its temperature increases.
 Particles attract each other.
Mixture, Pure Substance, Solution, and Alloy
 Pure Substance: a substance that is made up of only one type of particle. (e.g. water)
 Mixture: a substance that is made up of at least two different types of particles
 Solution: a uniform mixture of two or more substances. (e.g. apple juice)
 Alloy: a solid of two or more metals.
Diagram Summarising the Definitions:

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Physical and Chemical Properties and Changes
 Physical Property: a characteristic of a substance that can be determined without changing the composition of that substance.
 Physical Change: a change in which the composition of the substance remains unchanged and no new substances are produced.
 Chemical Property: a characteristic of a substance that is determined when the composition of the substance is changed and one or more new substances are produced.
 Chemical Change: a change in the starting substance or substances and the production of one or more new substances.
Some examples of evidence of chemical change are:
 A change of color – a new substance has formed that has a different color than the original substance.
 A change of odour - a new substance has formed that has a detectable odour
 Bubbles are visible not caused by heat - a new substance is produced in the form of gas.
Qualitative and Quantitative Property
Qualitative Property: a property of a substance that is not measured and does not have a numerical value, such as color, odour, and texture.
Quantitative Property: a property of a substance that is measured and has a numerical value, such as temperature, height, and mass.

Mass, Volume, and Density
 Density: a measure of how much mass is contained in a given unit volume of a substance; calculated by dividing the mass by its volume.
 Mass: amount of matter in an object.
 Volume: measure of the amount of space occupied by object
 Characteristic Physical Property: A physical property that is unique to a pure substance, and can be used to identify the substance.

Ex: A puffy marshmallow has the same mass as a squished marshmallow. However, a puffy marshmallow has a greater volume, so its mass to volume ratio is different, meaning the density is different. The particles in the puffy marshmallow are farther apart from each other. (the puffy marshmallow is less dense than the squished marshmallow.

Problem Solve: Identify the metal which is; 18.00cm long, 9.21cm wide, 4.45cm high, and has a mass of 14.25kg.
Given: L=18.00cm H=4.45cm W=9.21cm M=14.25kg
Required: Density of the metal (d) Analysis: density = mass/volume
Solution: Volume of metal shape= L x W x H =18cm X 9.21cm X 4.45cm =738cm3
Mass of Metal Shape= 14.25kg = 14, 250g
Density= Mass/Volume =14, 250g/738cm3 =19.3g/cm3 The metal is gold. Refer to 5.6, PG.193, Table1

Melting and Freezing Point
 Freezing Point: the temperature at which a substance changes state from a liquid to a solid; melting point & freezing point are the same temperature for a substance.
 Melting Point: the temperature at which a substance changes state from a solid to a liquid.

 Salt can “melt” ice because; when an impurity is added to water it interferes with the freezing process (lowers), and water does not become solid ice until the temperature drops even lower. Instead of ice freezing at 0oC, a mixture of 20% salt can lower the point down to -16oC.
 Ice, which is a solid, floats of water (liquid state of ice)! Why? Water particles are different. Due to the way they are