Chemistry

Working scientifically

Scientific developments

economic

social

personal

environmental

Atomic Structure

Compounds

bonds

Mixtures

Chromotography

filtration

crystalisation

distillation

Atoms

Protons

Neutrons

Electrons

elements = atomic number

isotope - more neutrons

different atomic form of the same element

Na 23 - mass, 11 atomic number

Electronic structure

outer shell filled or removed

Periodic table

Atomic weight was incorrect way of sorting

helps see patterns in properties

Metals and non-metals

most elements are metal

most metals are transition metals

have different physical properties

Transition metals

can have more than one ion

often coloured

make good catalysts

copper, gold, palladium

Group 1 elements

alkali metals

easily broken

try to get rid of their electrons

Higher up the periodic table, the electrons are further away from the protons

lithium, potassium

Group 7 elements

react with non-metals (including oxygen)

halogens are all non-metals with colored vapors

they are all toxic

chorine, bromine, fluorine

as you go down group 7 the halogens are less reactive

higher melting points as they go up

Group 0 elements

nobel gases

don't have space to take electrons or give them away

helium, radon, argon

Bonding, Structure and Properties of Matter

Ions

Bondings

States of matter

made when electrons are transferred

are charged particles

if a metal and a non-metal react together, the metal looses electrons to become positively charged. The non-metal gains them to become negatively charged

Group 1, 2, 6 and 7 are the most likely to form ions

Group 1 and 2 are metals and they loose electrons to form positive ions (cations)

Group 6 and 7 are non metals, they gain electrons to form negative ions (anions)

Dot and cross diagrams

show how share electrons

ionic compounds

have a structure called a giant ionic lattice

all have similar properties

high melting points

high boiling points

when soild can't conduct electricity

when liquid - the ions are free to move to can conduct

Covalent bonding

means sharing electrons

when non-metal atoms bond together they share pairs of electrons to make these

Metalic bondings

polymers

lots of small units are linked together to form a long molecule that has repeating sections

all of the atoms in a polymer are joined by covalent bonds

giant covalent structures

high melting and boiling points

don't conduct electricity

Allotropes of carbon

all kept together by covalent bonds

are different structural forms of the same element in the same physical state

are no bonds in the layers, they are held together weakly

involves delocalised electrons

very conductive

alloys are harder than pure metals

Nanoparticles

large surface area to volume ratio

diameter between 2.5 x10(-6)m - 1x10(-5),

Quantitative Chemistry

Relative formula mass

percentage mass of an element in a compound = A(R) x number of atoms of the element / M(R) of the compound x 100

The mole and mass

The avogadro constant = 6.02x10(pr of 23)

The mole and equations

volume of gas = mass of gas / m(r) of gas x24

Solutions

concentration = number of moles in solute / volume of solute

Atom economy and percentage yield

atom economy = relative formula mass of desired product / relative formula mass of reactants x 100

percentage yield = mass of product actually made / maximum theoretical mass of product x 100

Chemical Changes

Acids and bases

PH goes from 0-14

Acids and bases neutralise each other

Titrations

allow you to find exactly how much acid is needed to neutralise a measure volume of alkaline

Acids

Acids can be strong or weak

Acid + metal carbonate -> salt + water + carbon dioxide

Metals and their reactivity

Acid + metal -> salt and hydrogen

Metal + water -> metal hydroxide + hydrogen

Redox reactions

Electrolysis

means splitting up with electricity

metals can be extracted from their ores using electrolysis

Electrolysis and aqueous solutions

Energy Changes

Exothermic and endothermic reactions

Bond energies

Cells

Fuel cells

factors affecting the rate of reaction

hydrogen-oxygen fuel cells involve a redox reaction

cathode produces heat for the equation and water

annode uses the hydrogen to fuel the reaction

temperature

concentration of a solution or the pressure of the gass

surface area

the presence of a catalyst

they decrease the activation energy

can be used multiple times

enzymes are biological catalysts

Reversible reactions

if you change one thing the reaction does that to the other side

Organic Chemistry

Uses and cracking of crude oil

Alkanes and their reactions

Fractional distillation

Addition polymers

Hydrocarbons

alkanes have all C-C single bonds

C(n)H(2n+2)

are homologous series

first four alkanes methane, ethane, propane and butane

long chain hydrocarbons are hard to crack

alkane bonds c=c

burn with a smokey flame

addition of hydrogen is known as hydrogenation

alkanes turn bromine water colourless

steam can react with alkanes to form alcohol

plastics are made up of long chain molecules called polymers

Alcohols

Have a 'OH' functional group and end in -ol

ethanal can be made by fermentation

Carboxylic acids

esters can be made from these

they have the functional group COO

condensation polymers

for each new bond that forms a small molecule is lost

naturally occurring polymers

amino acids have an amino group and a carboxyl group

proteins are polymers of amino acids

DNA molecules are made from nucleotide polymers

simple sugars can form polymers

Chemistry of the atmosphere

Chemical Analysis

Using resources

Materials and their properties

composites are generally made of two different materials

Alloys

Pure metals don't always have the properities needed

alloys are typically a mixture of two different metals

Corrosion

Iron and steel corrode much more than aluminum

Both air and water are needed for iron to rust

if a nail is put in with boiled water and oil on top - will not rust

Two main ways to prevent rusting

Painting / coating

Electroplating - uses electrolysis

The Haber process

produces ammonia from nitrogen and hyrdrogen

reacting gases are passed over a iron catalyst

at above 450 degrees Celsius and at high pressure

The more atmospheres the more yield