Chemistry Eoy

Front 1

Solids

Back 1

• strong forces of attraction

• fixed position (latice arrangement) - definite shape and volume

• vibrates - increase heat you increase vibration

• slightly expands when heated

• can't be compressed - molecules packed closely together

•very dense

• Rejjjivokvic

Front 2

Liquids

Back 2

• some force of attraction

• free to move but still 'stick' together

• no definite shape but same volume

• molecules move constantly in random directions

• hotter liquid - faster molecules move so liquid expands

• can't be compressed - already packed together

• quite dense but not as much as solids

Front 3

Gases

Back 3

• no force of attraction so they have low densities

• free to move - always moving in random motion

• move in straight lines - only interacts when they collide

• no definite shape or volume - expands to fill container

• Gas exerts pressure on walls of container

• hotter the gas, faster molecules move - expands or pressure increase

• can be compressed because of the free space

Front 4

Melting

Back 4

1. Heat goes to the molecules

2. Vibration increases

3. Strong forces between molecules breaks and start to move.

4. The solid has now MELTED

Front 5

Evaporation

Back 5

1. Heat goes to the molecules so they move faster

2. Some molecules move faster than others

3. These molecules (at the surface) will escape by overcoming the forces of attraction

4. This is EVAPORATION

• If all the molecules have enough energy to escape, big bubbles of gas forms and this is called BOILING

Front 6

Other stuff on Changes of State

Back 6

• the heat energy supplied is used on breaking the bonds - instead of raising the temp.

• this means the temp. won't go up until bonds are broken

• when it is condensing or freezing, heat is given out because of the fusing of the bonds

• so temp. won't go up until all the bonds are reformed.

Front 7

Brownian Motion

Back 7

• Brownian Motion - jerky movement of smoke particles, seen through a microscope

• caused by air molecules hitting the smoke particles - pushing them about

• smoke particles reflect light - looks like bright speck

• pollen grains in water - can see Brownian Motion

Front 8

Diffusion

Back 8

• molecules in liquids + gases are in rapid random motion.

eg.

• Purple Potassium Manganate in water

• Brown Bromine in air

• HCl in Ammonia

1. dissolves into liquid or gas and molecules of the chemical gradually diffuses through liquid/gas

2. constant rapid random motion of all molecules causes it to spread evenly through whole liquid/gas

Front 9

Atoms - Nucleus

Back 9

• middle of atom

• contains protons + nucleus

• positive charge overall - because of protons

• nearly whole mass of atom is in nucleus

• compared to whole atom, it is tiny

• Protons mass is 1 and charge is +1

• Neutron mass is 1 and charge is 0

Front 10

Atoms - Electrons

Back 10

• move around nucleus

• really small - covers a lot of space

• volume of orbits shows how big atoms is

• occupy shells around nucleus

• It is negatively charged (-1)

• it has a mass of 1/2000

• if an electron is added or removed it will become charged and is then an ion

Front 11

Atomic No. and Mass No.

Back 11

• atomic number = number protons and electrons

• number of neutrons = number of protons - relative atomic mass

• bigger number (normally top one) = relative atomic mass

• mass number = roughly double atomic number

• most of time no. protons in nucleus = no. neutrons in nucleus

Front 12

Isotopes

Back 12

• Isotopes are different atomic forms of the same element, which have the same number of protons but different number of neutrons

• must have same atomic number but different atomic mass

• e.g. Carbon - 12 (P=6, E=6, N=6) and Carbon - 14 (P=6, E=6, N=8)

• only electrons affect the chemical behavior so isotopes don't 'behave' differently compared to the normal atoms

Front 13

Electron Shells

Back 13

• electron always occupy shells/energy levels

• lowest energy level filled first

• 1st shell - 2 electrons, 2nd shell - 8 electrons, 3rd shell- 8 electrons, the rest have 8 electrons

• stable atoms - full outer shells

• atoms in group 1 and 2 want to get rid of 1/2 electron(s) on outer shell (to make full shell) - once reacted, it is an ion

• Ions tend to stick to other ions with opposite charge

• Vice versa for group 7/8 atoms (they gain electrons) - stick to atom that gave electron (Ionic bonding)

Front 14

Ionic Bonding

Back 14

1. atom 1 gives up its outer electrons becomes an positive charged ion

2. atom 2 takes the electron and becomes an negatively charged ion

3. negative and positive attract and is bonded together

4. this is IONIC bonding

Front 15

Covalent Bonding

Back 15

• electrons are shared between atoms

• both atoms have full outer shell

• each covalent bond give 1 extra shared electron

• there has to be enough atoms to fill up the all the outer shells so 2 hydrogen is needed to fill up oxygen

Front 16

Ionic Substances - Simple Ions

Back 16

• elements that lose electrons - +ve ions (cations)

• elements that gain electrons - -ve ions (anions)

• when any of the above elements react = ions

• only element on opposite side of the periodic table will form ionic bonds

Front 17

Giant Ionic

Back 17

• ions form a aclosely packed regular structure like a solid

• very strong bond

• a crystal of salt is an example of a giant ionic lattice

• properties:

•high melting + boiling points because of the strong bonds

•solution conducts electricity because electrons are free to move

•molten conducts electricity

Front 18

Covalent Substances - Simple Molecular

Back 18

• form v. strong covalent bonds to make small molecule

• forces of attraction between molecules are weak which causes it to have low melting and boiling point

• most covalent are gases/liquid at room temp.

• don't conduct electricity because of no free ions

• don't dissolve in usually solvent

Front 19

Covalent Substances - Giant Covalent

Back 19

• similar to giant ionic but no charged ions

• all atoms joined by strong covalent bonds

• v. high and boiling point

• don't conduct electricity

• insoluble usually

• e.g. diamond and graphite (carbon atoms)

Front 20

Elements, Compounds and Mixtures

Back 20

• elements - have only 1 type of atom only

• mixture - have more than 1 type of atoms

• no chemical bond

• properties - mixture of the properties of the separate elements (e.g. iron powder + sulphur powder --> have magnetic bits of iron and yellow but of sulphur)

• compounds - v. difficult to separate back to the 2 original elements

• different properties to original elements

• formed during a chemical reaction

• iron (silver) + sulphur (yellow) ---> iron sulphide (grey solid lump)

Front 21

Filtration

Back 21

• can be used to separate mixtures of a solid and an liquid/soluble solid

• e.g. Rock Salt - mixture of sand and salt

1. if mixture with soluble solid - dissolve the mixture into a beaker

2. filter through filter paper in a funnel

3. evaporate solution in an evaporating dish

4. salt will be crystals (crystallisation) and sand in filter paper

5. Mixture separated

Front 22

Chromotography

Back 22

• used to seperate an ink or dye to find out what its made up of

1. drop spots of dye onto a baseline which was drawn by pencil on filter paper

2. place in a beaker containing shallow solvent but not exceeding the baseline

3. the solvent seeps up the paper

4. different dyes will travel different distances up the paper

5. compare unknown ink to known dyes to see which dyes the ink is made up of

Front 23

Distillation

Back 23

• used to separate a mixture of a liquid and a solid (e.g. ink and sea water)

• great for obtaining pure water from tap water

• distilled water can be used to top up batteries

Front 24

Fractional Distillation

Back 24

1. used to separating a mixture of liquids

2. even when mixed together, different liquids will boil off at their own temp.

3. The fractionating column ensures that the "wrong liquids condense back down properly boiling at the temp. on the thermometer will make it to the top

4. When liquid had boiled off, the temp. reading rises until the next faction starts to boil.

Front 25

Common Tests

Back 25

• Chlorine bleaches litmus paper (it becomes white)

• Oxygen relights a glowing splint

• Carbon Dioxide turns limewater cloudy (milky)

• Water - boiling point of 100 degrees

- turns white anhydrous Copper Sulphate blue

- turns anhydrous Cobalt Chloride paper from blue to pink

• Hydrogen causes a lighted splint to pop ("squeaky pop" test)