Classification of Matter

• Review of the classification of matter from lesson 1, August 24th, 2010.

Classification of Matter

• Matter can be classified as either a pure substance or a mixture.

Pure Substance

• Pure substances have a constant composition and can be either elements or compounds.
• Examples of pure substances: table salt (sodium chloride, NaCl), sugar (sucrose, C12H22O11), water (H2O), iron (Fe), copper (Cu), and oxygen (O2).

Compound

• Compounds contain two or more elements in a definite proportion by weight and are composed of more than one kind of atom.
• The smallest unit of a compound that retains all of the compound's properties is called a molecule.
• Examples of compounds: table salt (NaCl), sugar (C12H22O11), and water (H2O).

Heterogeneous Mixture

• Heterogeneous mixtures have properties and compositions that are not uniform throughout a sample.
• Examples of heterogeneous mixtures: salad, sand, stir-fry, mixed nuts.

Particle Theory

• All matter is made up of extremely tiny particles.
• Each pure substance has its own kind of particles, different from the particles of other pure substances.
• Particles are always moving
• Particles at a higher temperature move faster compared to lower temperatures.
• Particles attract each other

What is Matter?

• Matter is anything that has mass and volume.

Physical Properties

• Physical properties are the characteristics of a substance.
• The three states of matter are solid, liquid, and gas.
• These states are all physical states of matter
• Solids retain their shape and have a fixed volume.
• Liquids take the shape of their containers and have a fixed volume.
• Gases take the shape of their containers, and their volume can change.

Physical Property Observations

• Observations can be made using sight, smell, touch, taste, and sound.
• Sound can give additional information about the other senses.

Physical Properties Descriptors

• Colour or appearance can be colourless, white, black, shiny, or dull.
• Texture can be fine, course, smooth, or gritty.
• Odour can be odourless, spicy, sharp, or burnt.
• Clarity can be transparent, translucent, or opaque.
• Taste can be sweet, sour, salty, or buttery.

Typical Physical Properties

• Hardness is the measure of a solid's resistance to being scratched or dented.
• A harder material can dent a softer one.
• Ranking materials from hardest to softest: Diamond > Steel nails > Glass > Chalk.
• Malleability is the ability to be hammered or bent into different shapes.
• Example: Aluminum foil.
• Brittleness means a substance shatters easily.
• Ductility is the ability to be pulled into a wire, such as copper wires.
• Melting and Boiling Points: The temperatures at which substances change states.
• Water: Melting Point (MP) = 0°C, Boiling Point (BP) = 100°C.
• Crystal Form refers to the solid forms of minerals, like sodium chloride (table salt).
• Solubility is the ability of a substance to dissolve in a solvent; salt is soluble in water, pepper is not.
• Viscosity refers to how easily a liquid flows; the thicker the liquid, the more viscous it is.
• Density refers to the amount of mass per unit volume of matter, measured in kg/cm³.

Chemical Properties

• Chemical properties describe the behaviour of a substance as it becomes a new substance.
• Combustibility is the ability of a substance to burn and requires oxygen.
• Light sensitivity is a chemical property that can cause new substances to form when exposed to light.
• Reacting with an acid is a chemical property where a gas and bubbles are produced when acid is poured on a substance.

Physical Changes

• Physical changes involve a substance remaining the same; it may change form or state.
• All changes of state are physical changes.
• Dissolving is a physical change.
• Sugar remains sugar when dissolved, and can be recovered if the water is boiled off.
• Most physical changes can be reversed.

Chemical Changes

• In a chemical change, the substance transforms into one or more different substances with new properties.
• Most chemical changes are difficult to reverse.
• The new substances are not likely to combine and form the original substance.

Clues Indicating a Chemical Change

• Change in colour: The final product(s) may have a different colour than the starting material(s).
• Formation of a solid (precipitate): Final materials may include a substance in a state that differs from the starting material(s).
• Formation of a gas: The final materials may include a substance in a different state than the starting material(s).
• Release or absorption of heat: Energy (light, electricity, sound, or most commonly heat) is given off or absorbed.
• Changes are difficult to reverse.