NAT 5 CHEMISTRY

4 factors that can affect the rate of a chemical reaction.

Temperature, concentration,particle size and use of catalyst

homogeneous catalyst

catalyst is in the same state as the reactants, they are available in all states

heterogeneous catalyst

catalyst is in a different state from the reactants, only available in solid state

atomic number

atomic number of an element tells you how many protons an atom of that element has

3 particles in the atom

electron, neutron and proton

mass of electrons

nearly zero

mass number

number is equal to the number of protons+number of neutrons

what are isotopes?

atoms with the same atomic number but different mass numbers

what is an ion and how are they formed?

a charged particle and formed when an atom gains or loses an electron

what ions do metals form ?

postive ions (as they lose electrons)

what ions do non-metals form?

negative ions (as they gain electrons)

the _________ ________ have a stable electron arrangement

noble gases

what is a molecule?

a molecule is two or more atoms held together by covalent bonds

what is a covalent bond?

the electrostatic force of attraction between the positive nuclei negative shared pair of electrons

a __________ ____________ is made up of molecules that contain two atoms

diatomic molecule

diatomic molecule

fluorine, chlorine, oxygen, hydrogen, nitrogen, bromine and iodine

tetrahedral molecule shape

pyramidal molecules

linear molecules

bent molecules

what is an ionic bond?

the electrostatic force of attraction between a positive metal ion and a negative non-metal ion

ionic lattice

property of covalent molecular bonded substances

LOW melting and boiling points

properties of ionic substances

HIGH melting and boiling points, conducts never as a solid but only when molten or in solution

mole calculations formula

acids

have a pH lower than 7, have a greater concentration of H+ ions than OH- ions.

why do acids and alkalis conduct electricity?

they conduct electricity because they have ions that are free to carry the charge

what oxide produces an acidic solution?

Soluble non-metal oxides

what oxide produces an alkali solution?

soluble metal oxides

what are spectator ions?

ions that are present during the reaction but are unchanged by the reaction

homologous series

a family of compounds with similar chemical and physical properties that can be represented by a general formula

general formula for alkanes

CnH2n+2

general formula for alkenes

CnH2n

general formula for cycloalkanes

CnH2n

what are saturated hydrocarbons?

hydrocarbons that only contain single carbon to carbon bonds

what are isomers?

isomers re compounds with he same molecular formula but different structural formula

functional group of alcohols

-OH (hydroxyl)

uses of alcohols

solvents in perfumes, thermometers, fuel

functional group of carboxylic acids

-COOH (carboxyl)

uses of carboxylic acids

manufacture of esters, soaps, medicines and vinegar

alcohol + carboxylic acid ->

ester +water

uses of esters

solvents, perfumes and flavourings

functional group of esters

-COO (ester link)

how are esters formed?

by the condensation reaction known as esterification between and alcohol and a carboxylic acid

combustion

when a substance burns it reacts with oxygen and this is know as combustion

commonly used fuels

carbohydrates, alkanes and alcohols

what are carbohydrates fuels?

carbohydrates such as glucose as used to power our bodies

what is a fuel?

a fuel is a substance that reacts exothermically with oxygen

an _____________ ____________ is one which heat energy is given out

exothermic reaction

what is an endothermic reaction?

a reaction in which heat energy is taken in. this means that the products have more energy than the reactants because energy has been absorbed

formula used to calculate the energy released during combustion:

Eh= c x m x Δt

what is metallic bonding?

the electrostatic force of attraction between the positive ions and the negative delocalised electrons between two metals

metallic bonding

metals + water ->

metal hydroxide + hydrogen

metal + acid ->

salt + hydrogen

metal + oxygen ->

metal oxide

what is a cell?

a cell is made up of two different metals connected by an electrolyte

what is an electrolyte?

an ionic solution that is used to complete the circuit

the flow of electrons is produced because of the _____________ in reactivity of the two metals

difference

electrons will flow from the ______ reactive metal to the _______ reactive metal

most (oxidation) , least (reduction)

oxidation is ______ of electrons

Loss

reduction is ______ of electrons

Gain

what is the purpose of an ion bridge?

to complete the circuit, simply a piece of filter paper soaked in salt water or some other ionic solution

fuel cells

what happens in displacement reactions?

a reactive metal displaces a metal that is less reactive from solution

ores

when metals are found not as a pure metal but as a compound

what is a monomer?

small molecules that combine to form a polymer

what is a polymer?

large molecule formed by combing many monomer molecules

what extra is produced in condensation polymerisation?

water or small molecules such as hydrogen chloride

three main nutrients in fertilisers

-potassium (K)

-nitrogen (N)

-phosphorous (P)

what are the two types of fertilisers?

natural (e.g. manure) and synthetic (man-made)

ammonia

uses of ammonia

can be used to make other fertilisers, explosives, medicines and cleaning products

ammonia is an _______________ _____

alkaline gas

what experiment can be done to test the solubility of ammonia?

'ammonia fountain'

what does the haber process produce?

Ammonia

haber process

where does the nitrogen and hydrogen come from, that are used in the haber process?

nitrogen(N) from air and hydrogen (H) from steam or methane

what catalyst is used in haber process?

iron catalyst

what temp and pressure is used in the haber process?

400°C and 200 atmospheres

N2(g) + 3H2(g) ->

2NH3 (g)

how does the iron catalyst speed up the reaction (haber process) ?

it is broken down into small pieces to increase its surface area and therefore its effectiveness as a catalyst

what happens to the nitrogen and hydrogen that haven't been converted (haber process)?

put back into the reaction chamber to make the whole process more economic

how is nitric acid produced in an economic way?

ostwald process

what catalyst is used the in the ostwald process?

platinum gauze catalyst at 800°C

ammonia is passed over the platinum catalyst, this produces _________ __________ which combines with oxygen to form nitrogen dioxide.

nitrogen monoxide

nitrogen can be easily converted into nitric acid by?

dissolving it in water

the ostwald process is an ______________ __________, so once the reaction is started the heat can be removed and the catalyst will continue to glow red hot.

exothermic reaction

3 types of radiation

alpha , beta and gamma

what is radioactivity?

the result of unstable nuclei emitting energy or a particle to form a more stable nuclei

alpha particle

what are alpha particles?

slow moving positively charged particles that come from the nucleus of a radioactive element

what will alpha radiation be stopped by?

a few cm of air or a sheet of paper

beta particle

what are beta particles?

fast moving, negatively charged particles that are formed when a neutron from the nucleus splits into a proton and an electron

what will beta radiation is stopped by?

thin metal foil

gamma radiation

what are gamma waves?

they are non particulate. High energy electromagnetic waves.

penetration of each type of radiation

effect of magnetic field on radioactive elements