Transcript Science 9 – Matter and Chemical Change

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:
• H2O
• O2 (diatomic molecule)
• CO2
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: H2O
• 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