Chemistry
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Characteristics of Matter
Mixtures –> Homogeneous (Solution) and Heterogenous (Mechanical) Pure Substances –> Elements and Compounds
Physical Change
Substance remains same substance even though it may change state or form (dissolving, cutting, changing state)
Chemical Change
Original substance changed into one or more substances (colour change, gas/light produced, energy released/absorbed)
Ionic Bonding
Occurs between metals and non-metals where metals transfer electrons to non-metals
Molecular/Covalent Bonding
Occurs between two non-metals where pairs of electrons are shared
Diatomic Elements
Have No Fear Of Ice Cold Beer H₂(g), N₂(g), F₂(g), O₂(g), I₂(s), Cl₂(g), Br₂(l)
Laws of Conservation of Mass
Total mass of reactants = total mass of products
Synthesis
A + B –> AB
Decomposition
AB –> A + B
Single Displacement
A + BC –> AC + B
Double Displacement
AB + CD –> AD + CB
Combustion
X + O₂(g) –> XO + energy 1. Lots of O₂ 2. Burns quickly 3. Releases energy 4. Forms oxides
Exothermic Reactions
Has energy as a product (vessel gets warm)
Endothermic Reactions
Has energy as a reactant (vessel gets cold)
Acids
Molecular compounds that release hydrogen ions when dissolved in water - Tastes sour, sticky, conducts electricity - Reacts with metals and carbonates
Binary Acids
Contains hydrogen and another non-metal (prefix “hydro-“)
Oxy Acids
Contains a polyatomic ion and hydrogen ions (named after polyatomic ion with “ic” ending)
Bases
Ionic compounds that release hydroxide ions (sometimes carbonate ions) when dissolved in water - Taste bitter, slippery, conducts electricity - Reacts with natural products (proteins)
Acid-Base Indicators
Bromthymol Blue: acid = yellow, base = blue Phenolphthalein: acid = colourless/light pink, base = dark pink Litmus: acid = red, base = blue
pH Scale
“Power of Hydrogen” - measure of concentration of hydrogen ions (1 unit on pH scale = 10 x concentration in solution)
pH Scale Applications
• Different plants like soils of differing acidity • Basic shampoo (high pH) softens and straightens hair; acidic shampoo (low pH) restores hair’s flexibility and shine • High pH soap removes outer layer of dead skin cells
Neutralization
Type of double displacement reaction that occurs when an acid and base react to form products with a neutral pH (acid + base –> water + ionic compound (salt))
Neutralization Applications
• Acidic soil must be neutralized (with lime) for plants • Chemical spills into the environment must be neutralized • Antacid neutralizes stomach acid