Chemistry - 1 Atomic Structure

Basic unit of matter

A pure substance made of only one kind of atom

A chart of the elements showing the repeating pattern of their properties

A vertical column of similar elements in the periodic table

The horizontal lines of elements related via their number of electrons and protons

Begins before boron and after aluminium

two or more atoms held together by covalent bonds

A substance made up of atoms of two or more different elements joined by chemical bonds

Center of an atom

A subatomic particle that has a negative charge

an atom that has become charged by losing or gaining electrons

an atom of the same element with a different number of neutrons

physical

chemical

atom written as its shells, e.g. 2, 8, 1

the element's Group

tiny, hard, indivisible spheres - each element's atom has a different mass

JJ Thomson

cathode ray tube experiment

evacuated glass tube in which a stream of electrons emitted by a cathode strikes a fluorescent material, causing it to glow

JJ Thompson put positively and negatively charged plates around the cathode ray tube and saw that the ray curved towards the positive plate. He deduced that there must be electrons

plum pudding model

Ernest Rutherford

Gold foil experiment

- gold foil placed in the middle of a fluorescent screen
- alpha particles shot at gold foil
- most particles went through
- some were deflected

- atom is mostly empty space
- nucleus has a positive charge
- electrons float around nucleus

Nuclear/planetary model

Niels Bohr

James Chadwick

- alpha particles shot at materials
- emitted rays with no charge
- rays with no charge dislodged protons from paraffin
- deduced that they were neutrons

number of protons in an atom

number of protons + number of neutrons

Describes two liquids that are soluble in each other

Some vapour may be given off before the substance reaches boiling point - the boiling points are too close together.

Used to separate liquids with similar boiling points using a fractionating column

a glass tube filled with beads

- Vapours must pass over the beads to reach the condenser
- The substance with the higher boiling point is more likely to condense lower down, where the temperature is lower
- The substance with the lower boiling point will continue to rise through the tube and reach the condenser

- Use of ethanol as a biofuel
- In oil refineries, to separate crude oil

A technique that is used to separate the components of a mixture based on the tendency of each component to travel or be drawn across the surface of another material (solubility)

- Draw a pencil line on some absorbent chromatography paper to indicate the starting point
- Use a capillary tube to dab small amounts of solution on the line
- Suspend the paper in a small amount of water (up to the line)
- See which solution travels the furthest

A combination of two or more substances that are not chemically combined

- Compounds have a fixed composition
- Mixtures have no fixed composition

- Compounds must be separated by chemical reactions
- Mixtures can be separated by physical means, using the properties of each separate substance

- Compounds contain different elements chemically bonded
- There are no chemical bonds between atoms of a different substance in a mixture

A process used to separate an insoluble substance from a solvent - usually with filter paper and a funnel

- The sandy water is poured through filter paper
- The sand collected on the paper is rinsed to remove any remaining soluble solvents
- The sand is dried in a warm oven to evaporate off the water

The formation of crystals by evaporating a solvent from a saturated solution

- Heat an evaporating dish containing the saturated solution (either in a water bath or directly on the gauze and tripod)
- Stop heating at the point of crystallisation
- Leave the rest of the solvent to evaporate at room temp

liquid that has passed through a filter

A liquid substance capable of dissolving other substances

A substance that is dissolved in a solution.

A process that separates the substances in a solution based on their boiling points

- Solution is heated over Bunsen burner
- A thermometer is placed so that we can record the gas's temperature
- the gas enters a condenser where it is cooled and again becomes liquid
- The liquid enters another glass

A tube with an outer jacket that has water flowing through it, acting as a coolant to condense the vapours inside

A starting material in a chemical reaction

The elements or compounds produced by a chemical reaction.

an equation in which the reactants and products in a chemical reaction are represented by words

an equation that helps you see how much of each substance is involved in a chemical reaction by showing the chemical symbols and formulae of all the reactants and products involved

Matter is not created nor destroyed in any chemical or physical change

Symbols to show the state of a substance - solid (s), liquid (l), gas (g) and aqueous (aq)

solutions with water as the solvent

- Write down all the atoms and the numbers of them on the side of the reactants and of the products
- Change one necessary coefficient
- Rewrite/reevaluate the first step
- Repeat until balanced