1.1 - matter

pure substances

consists of only one type of particle with a fixed composition and uniform properties throughout. They are elements or compounds.

element

substance that consists of only one type of atom. They are represented by chemical symbols.

compounds

substances formed when two or more different elements are chemically bonded together in fixed proportions. They can only be separated using chemical reactions. The fixed chemical formula’s properties differ from the elements they are made of.

mixture

a mixture contains two or more elements or compounds that are physically combined but not chemically bonded. the compositions can vary and is separated only by physical methods.

homogeneous

Particles are evenly distributed so it has uniform composition and properties throughout.

heterogeneous

components are not evenly distributed so it has non-uniform composition. Its properties are not the same throughout.

filtration

used to separate insoluble solids from a mixture of a solid and liquid or solution using filter paper.
1. pour the mixture through a funnel lined with filter paper
2. liquid (filtrate) passes through, leaving the solid (residue behind)

solvation

the process where solvent molecules surround and separate solute particles when a solute dissolves.

1. add the mixture to a suitable solvent

2. stir to help soluble substance dissolve

3. soluble substance forms solution while insoluble remains undissolved.

crystalization

used to separate a dissolved solid from a solution when the solid is more soluble in a hot solvent than the cold.

1. heat the solution gently to evaporate some solvent

2. allow the solution to cool until saturated

3. test saturation using a lass rod

4. leave saturated solution to cool slowly allowing crystals to form as solubility decreases

5. filter to collect crystals and wash crystals with distilled water and dry on filter paper

recrystallization

used to purify an impure solid by dissolving it in a hot solvent and allowing it to crystallize as the solution cools.

1. add a minimum amount of hot solvent to the impure solid until it dissolves

2. Allow solution to cool to room temperature until crystals of the purified product begin to form.

3. collect crystals using Büchener apparatus

4. wash crystals with fresh cold solvent

5. dry crystals

simple distillation

A method used to separate a solvent from a solution, or liquids with significantly different boiling points, by heating to vaporize the more volatile component and then cooling to condense it.

1. heat the solution in a round-bottomed flash

2. the liquid with teh lowest boiling point evaporates first

3. the vapour passes into the condenser where it cools and condenses

4. the distillate (purified liquid( is collected in a clean beaker

fractional distillation

used to separate two or more miscible liquids with similar volatility.

1. heat the mixture ina. round-bottomed flask

2. the liquid with the lowest boiling point evaporates first

3. vapor passes up the fractioning column

4. vapor enters the condenser, cools and condenses

5. the distillate is collected in a beaker

6. as the temperature rises, the next component evaporates and is collected in turn.

paper chromatogrpahy

used to separate dissolved substances in a mixture based on differences in solubility and absorption to the paper.

1. draw a pencil line near the bottom of the chromatography paper

2. place small spots of the sample mixture on teh line

3. suspend the paper ina. container with a shallow layer of solvent

4. let the solvent move up by capillary action

retention factor

distance travelled by solute / distance travelled by solvent front

kinetic molecular theory

the kinetic molecular theory explains the physical properties of matter (solids, liquids, gas) in terms of energy, arrangement, and motion

solids

Solids have a fixed shape and volume. Particles are closely packed in a regular, ordered pattern. They vibrate in place at a high density.

liquids

liquids have fixed volume but takes the shape of their container. particles are close together but can slide past one another. it has a medium density and energy.

gas

gases have no fixed shape or volume. particles are widely spaced and randomly arranged. they move quickly and randomly in all directions. they have low density. highest energy

solid to liquid, liquid to solid

melting, freezing

liquid to gas, gas to liquid

vaporization, condensation

solid to gas, gas to solid

sublimation, deposition

change of state

During a change of state, the energy supplied is used to overcome intermolecular forces rather than increase kinetic energy. Therefore, the temperature remains constant while the particles become further apart or change their arrangement.

temperature

temperature is the measure of the average kinetic energy of the particles in a substance. Kelvin is the SI unit. Temperature and avaerage kinetic energy are directly proportional.

kelvin from celsius

+273.15

celsius from kelvin

-273.15