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Introduction to Chemistry

Introduction to Chemistry. u nit 1. Chemistry is…. The study of the substances around us Teaches us how to change substances into new ones Teaches us how to do this in a socially and environmentally safe way . Properties can be physical or chemical …. Physical Properties.

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Introduction to Chemistry

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  1. Introduction to Chemistry unit 1

  2. Chemistry is… • The study of the substances around us • Teaches us how to change substances into new ones • Teaches us how to do this in a socially and environmentally safe way

  3. Properties can be physical or chemical…

  4. Physical Properties • A description of a substance that does NOT involve forming a new substance • Examples: • Colour • Texture • Shape • Hardness • Viscosity • Odour • Melting point • Boiling Point • Lustre • Density • Transmission of Light • Clarity (transparent/opaque) • Taste • State (solid/liquid/gas)

  5. Chemical Properties • A description of what a substance does as it changes into one or more new substance(s) • Examples: • Corrosion • Reactivity • Combustibility: the ability of a substance to burn (requires oxygen) • Flammable: the ability of a substance to burn when exposed to a flame • Light Sensitivity: the ability of a substance to change to a new substance in the presence of visible light

  6. Sort: Liquid, 23oC, reactive, brittle, very soluble, 250mL, non-flammable, square, smooth, combustible, yellow, solid

  7. Sort:

  8. Physical Change • A change that does NOT produce a new substance • only a change of state • new substance has the same properties as the old one • Examples: • Change of state (ex. melting, evaporating, condensation, dissolving)

  9. Chemical Change • The change that a substance goes through to produce a NEW substance • Most cannot be reversed • New substance is different from the original – it has different properties

  10. Examples of chemical reactions • raw egg becomes cooked egg • cake mix becomes cake • paper becomes ash • steel becomes rust

  11. Chemical Change con’t • Evidence of a chemical change: 1. A new colour appears 2. A solid (precipitate forms) in a liquid 3. Heat or light is produced or absorbed 4. The change is (generally) difficult to reverse 5. Bubbles of gas are formed

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