Chemistry Notes

Chemical compound, Chemical bond, Ionic compound

5.1 Properties and Changes
-Physical properties are characteristics or descriptions of a substance that may help identify it, for example: odour, colour, taste, texture. Whereas with chemical properties; this is the description of what a substance does as it changes into one or more new substances, for example: corrosion, flammability, bleaching ability.

-When a physical change occurs, the substance remains the same even though it may have changed state or form, for example: melting, evaporation, dissolving. When a chemical change occurs, the original substance will change into one or more different substances that have different properties, for example: burning , cooking, rusting.

-Evidence that a Chemical Change has occurred -->
1. new colour 2. heat or light is given off 3.bubbles of gas form 4. new precipitate 5. difficult to reverse 6. starting material is used up

5.4 Patterns and the Periodic Table
-A period is a row of elements organized horizontally. A group is are columns of elements with similar properties (vertically).

-Alkali Metals, Alkaline Earth Metals, Halogens, Noble Gases; are the four groups from the periodic table.

Proton ---> Positive--->p+ ---> nucleus
Neutron---> Neutral--->n °---> nucleus
Electron---> Negative--->e- ---> orbital

-An ion is a charged particle that results when an atom gains or loses 1 or more electrons. Whereas an atom may have valence electrons on its outer orbit; this determines if the element is stable or unstable.

5.6 Ionic Compounds
An ionic compound is a pure substance made up of one or more cations joined to one or more anions. An ionic bond is the force of attraction between cations and anions. It's also when electrons are transferred between cations and anions.

Properties of Ionic Compounds: Hard, brittle solids with high melting points. They are conductive when dissolved in water (soluble). When in solid form Ionic solids are good insulators. ex. Salt (Sodium chloride- NaCl)...
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