Chemistry Unit 1.1 Matter, Atoms, and Electrons

Atoms

basic unit of all matters

Element

Substance that contains only one type of atom. Cannot break down.

Compound

Substance that contains more than one type of atom. Chemically combined, fixed ratio = chemical formula.

Mixture

Contains more than one type of pure substances (not chemically combined)

Homogeneous

Uniform throughout, components can mix with each other, alloys etc.

Heterogeneous

Not uniform throughout, components cannot be mixed together, suspension, colloid, etc.

Separating techniques

Magnetism, Gravity Filtration, Vacuum Filtration, Evaporation, Crystallization, Recrystallization, Separating funnel, Distillation, Chromatography

Magnetism

When one of the components in a mixture of solid is magnetic, you use a magnet to separate it from the mixture

Gravity filtration

The process where you separate a solid with liquid or gas by using a filter. Used to separate mixture with solid only (when one of the components is soluble). Residue: solid that cannot pass through. Filtrate: fluid that passes through.

Vacuum filtration

Faster than gravity filtration. Buchner flask. Connected to a vacuum pump. Used when the residue is a desired product.

Crystallization

The process where crystals are formed in a saturated solution. When the solution is heated, crystals will start forming, indicating the solution is saturated. The saturated solution is left to cool for the crystals to “grow”. Slow process (large solid formed). Evaporation: Fast process (small solid formed).

Recrystallization

Separates solid from a mixture through the difference in solubility. Solvent will be chosen: separating the mixture into 3 parts: impurities that is insoluble in the solvent (filtration used to remove), impurities that is soluble in the solvent (remain in solvent), desired product that is soluble only at high temperatures, collected or separated through vacuum filtration.

Separating funnel

Apparatus used to separate 2 immiscible liquid. Layer with a higher density will be at the bottom and drained through the tap. Used to extract solid from the solution using a selected solvent.

Distillation

The process that separates solvent from solute or two miscible liquid using the difference in boiling points. The solvent that has a lower boiling point will evaporate first. The vapor will then condense when passing throuigh the condenser and collected.

Fractional distillation

Used to separate two different liquids. Boiling points are closer, fractionating column is added. Used to increase the surface area to facilitate the cooling process. Liquids with boiling points that are closer will be separated more efficently.

Chromatography

Used to separate substance based on affinities to stationary and mobile phase. Stationary phase: solid medium where substance will move through. Mobile phase: liquid or gas that carries the substances to be separated. Types: paper, thin layer.

Kinetic molecular theory

Every atom in any substances are constantly moving, even in a solid state. Temperature is an indication of how much energy (KE) the atoms in a substance contains.

Phase changes

Atoms will gain enough energy to “break through” the structure and they will start to change state. No temperature change at the melting or boiling point.

Boiling point

used to indicate purity

Absolute zero and kelvin temperature scale

Lower T = Lower KE, Absolute zero: -273.15, Celsius = Kelvin - 273.15