Science 9 – Matter and Chemical Change A Brief Unit Review

Topic 1 – Exploring Matter Particle Model of Matter –All matter is made up of tiny particles that are always moving. More energy, more movement. In a pure substance the particles are the same. Particles have attractive forces between them. Particles have spaces between them. States of Matter Classification of Matter –Matter  Pure Substace  Elements or Compounds L> Mixtures  Homogeneous (solution) or Heterogeneous

Topic 2 – Changes in Matter Physical Changes –The particles stay the same but their physical appearance may have changed. –Can be reversed easily. –Example: Change in State or Dissolving

Topic 2 – Changes in Matter Chemical Change –Difficult/Impossible to reverse –A reaction –New products are formed (bubbles, precipitate, new odor) –Other evidence: Colour change, release of heat (exothermic), heat is absorbed (endothermic). –Example: Combustion, acid-base neutralization.

Topic 2: Changes in Matter Physical Properties of Matter –color, texture, lustre, smell, state, melting point, boiling point, hardness, malleability, ductility, crystal shape, viscosity, solubility, density and conductivity (electrical and heat). Chemical Properties of Matter –reaction with water/air/acids/heat, ability to burn (combustibility), toxicity, stability.

Topic 3: Elements Law of Conservation of Mass –In a chem. rxn, mass of the products = mass of the reactants Law of Definite Composition –In compounds, atoms arrange themselves in defined ratios. For example in water, there are 2 hydrogen atoms for every oxygen atom. Atomic Theory (Dalton) –All matter is made up of atoms –Atoms cannot be created/destroyed/divided into smaller particles. –Atoms of the same element are identical in size and mass. Different elements have different sized atoms. –Atoms combine to form compounds.

Topic 3 - Elements Atomic Models –Raisin Bun/Plum Pudding Model (Thompson) –Planetary Model (Rutherford) –Atomic Model (Bohr) –Electron-Cloud/Quantum Model

Topic 4 & 5 – The Periodic Table of Elements

Topic 4 & 5 – The Periodic Table Mendeleev assembled the periodic table by increasing atomic mass. Each element has an atomic number. This is the # of protons an element has in its nucleus. Each element as a symbol, eg. A for Argon Each element has a mass number. This is the # of protons and neutrons it has.

Topic 6 - Compounds Ionic Compounds –Metal + Non metal. –Each atom becomes an ion (charged particle) in solution. –Therefore they are conductive when liquid/aqueous. –Very soluble in water. –Solids at room temp. –Example: NaCl

Topic 6 - Compounds Molecular Compounds –Non-metal + Non-metal –Non conductive in solution –Example: H 2 O O 2 (diatomic molecule) CO 2

Topic 6 - Compounds Naming Compounds –Write the name of the first element. –Write the name of the second element, but change the ending to -ide. For example, oxygen becomes oxide, fluorine becomes fluoride. –IF YOUR COMPOUND IS IONIC, you’re done! –IF YOUR COMPOUND IS MOLECULAR, add a prefix (mono, di, tri, tetra) to each atom to indicate the quantity. –Example: H 2 O Dihydrogen monoxide

Topic 7 – Chemical Reactions Reactants  Products Bonds break (releases energy) and reform (uses energy). Exothermic rxns give off extra energy, as heat. Endothermic rxns absorb energy (gets cooler)

Topic 8 – Reaction Rate Catalysts increase the rate of reaction. A common example are enzymes in your digestive system. Inhibitors slow down reactions. Corrosion is the oxidation of metals (ex. Rust: iron + oxygen  iron oxide/rust). To prevent corrosion, we plate our metals (galvanization is zinc plating). Combustion: Fuel + oxygen  carbon dioxide + water + energy