Chemistry Gr 9 & 10 Review

Topics: Chemical substance, Metal, Chemical compound Pages: 6 (841 words) Published: September 16, 2014
Module One: Grade Nine Topics

Physical Change: This is a usually reversible change in which the form of matter is altered, but is not chemically changed to another substance. Melting an ice cube is an example of a physical change.

The ice cube changes states: from a solid to a liquid (water). You can physically see this change.
No new substance is formed: the matter in the liquid is the same as it was in the ice cube. It is reversible: you can freeze the liquid to turn it back to ice. Therefore this is an example of a physical change!

Dissolving sugar into water is also an example of a physical change. The sugar disappears into the water making a solution.
No chemical reaction occurs.
No new substance is formed: it is just sugar in water
It is also reversible: if you boil the water there will be traces of sugar left. Therefore this is an example of a physical change.
Chemical Change: A usually irreversible chemical reaction that causes a change in matter’s chemical properties resulting in the formation of another substance.

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When a chemical change occurs after a chemical reaction there are clues for you to know that the change was chemical and not physical.

Pure Substance: This is a substance that is made up of only one type of molecule or atom. (Making it pure). There are 2 types of pure substances: an element and a compound. Element: A substance that cannot be broken down by chemical means. An element is a pure substance because it is made up of one type of atom it also cannot be broken down further into another substance. (This deems it pure) Compound: A substance that is made up of 2 or more elements, it is still considered a pure substance because while the elements bond so do the atoms. Therefore there is only one type of atom in the compound. Impure substance- Mixture: A substance that is made up of 2 or more different particles (Making it impure). There are 2 different types of mixture: Homogenous and Heterogeneous mixtures. Homogenous Mixture: This is a mixture of different substances that you can physically view that they are separated. (Not Uniform) Heterogeneous Mixture: A mixture of different substances that are separated but you cannot physically view. (Uniform) 1 2 3 12 17 18

Group 1 Alkali metals: These are highly reactive metals.
Group 2 Alkaline earth metals: Less reactive metals than the Alkali metals Group 3-12 Transition metals: Some different metallic properties Group 17: Halogens: Highly reactive non metals
Group 18 Noble gases: Very unreactive gases
Group 18 (Hydrogen): Gas at room temperature
More reactive the less the electrons the element has to lose or gain, less reactive if valence or full or half full it is harder to lose or gain electrons

Module Two: Grade 10 Topics

My results in the warmup were accurate and precise. This is because my measured time was very consistent (precise) to 20s, it is also accurate I was usually close to the 20s. Ionic Compound
Covalent Compound
Physical Properties
-High melting and boiling points
-Are hard and brittle
-Conduct electricity when dissolved in water
-Ionic solids are good insulators.

Physical Properties
-Low melting and boiling points
-Tend to be soft and flexible
-Don’t conduct electricity when dissolved in water
-Usually don’t dissolve well in water
Chemical Properties
-Tend to be more flammable than ionic compounds.

5. a) Synthesis: Is a type of chemical reaction in which two or more simple substances combine to form a more complex product -This reaction usually occurs between elements always resulting in a compound product. -Ex: The combination of iron and sulfur to create iron (II) sulfide. 8Fe+S8= 8FeS

b. Decomposition: Decomposition reactions occur when a compound breaks up into elements or into simpler compounds. General Equation: AB—> A+B...
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