Chemistry EOY yr 9

Atoms, Rates of Reaction, Reactivity of Metals, Organic 1

Why are elements different?

they contain different numbers of protons, neutrons and electrons

Proton

mass 1 charge +1

Electron

mass 0 charge -1

neutron

mass 1 charge 0

Do atoms have an overall charge?

no, they are neutral

the number of protons is equal to

number of electrons

24
Mg what is the top number and what does it mean
12

mass number and is number of protons and neutrons

24
Mg what is bottom number and what does it mean
12

atomic number and its the number of protons

1234

2888

how do you show a shell is full

put a dot next a number

What is in the nucleus of an atom?

protons and neutrons and all the mass

periods

Horizontal rows on the periodic table

groups

columns on the periodic table

how are elements arranged into periods

number of shells with electrons in

how are elements arranged into groups

number of outer shell electrons

valency

the number of bonds an atom can form

rule for valency

add atoms until all bonds are full

how to know groups valency

1234567
1234321

Dalton's Model

solid sphere 1808

Plum Pudding Model

1887-JJ Thomson- electron discovered led to ball of pos charge w/ electrons embedded in it

alpha particle scattering experiment

1905-9 plum pudding model had to change

Bohr Model

electrons orbit nucleus at set distances- shells

Proton Discovery

Rutherford-1919 - nucleus is made up of protons and neutral particles

Neutron Discovery

James Chadwick in 1932

Law of Conservation of Mass

in a chemical reaction you never lose or gain an atom

balancing equations

number of atoms on each side must be equal

Law of Constant Composition

elements combine in fixed ratios

2NH3

2 nitrogen atoms 6hydrogen atoms

NH3

1 nitrogen atom 3 hydrogen atoms

on a graph where curve is steepest it means

the reaction is fastest, most reactant particles, most collisions between reactant particles,

rate =

amount of product formed/time

Magnesium + hydrochloric acid >

Magnesium chloride + hydrogen

how do chemicals react

their molecules must collide and have have energy greater than activation energy

effect of a catalyst

decreases activation energy, percentage of successful collisions increases, rate increases

how do catalysts lower activation energy?

By providing an alternative reaction pathway

What is crude oil derived from?

Ancient biomass, mainly plankton

Mixture definition

Two plus elements not chemically combined- can be separated by physical methods

Where is crude oil found?

In rocks

Hydrocarbon

Molecules of hydrogen an carbon only

Hydrocarbons are mostly alkanes

General formula of alkanes

CnH2n+2

Methane

CH4

Ethane

C2H6

Propane

C3H8

Butane

C4H10

Combustion of carbon word equation

Hydrocarbon+ oxygen —> carbon dioxide + water

Exothermic

Energy is released

What happens in and incomplete combustion

Not enough oxygen

Hydrocarbon + oxygen—> carbon monoxide + water

how does fractional distillation work?(5 bullet points)

• crude oil into tower vaporises

• gases rise

• tower gets colder going up

• hydrocarbons condense when they reach their boiling point, big molecules further down

• they are drawn off

rust (3 bullet points)

• corrosion of iron.

• only iron rusts

• air+ water are both necessary

prevention methods (6 bullet points)

• exclude oxygen and water

• eg oil,

• grease,

• paint,

• tin plate

• sacrificed protection

galvanise

zinc plate excludes water/air + if scratched will react instead of the iron bc zinc is more reactive

magnesium lumps

on a ship they react and are replaced but then iron doesn’t react

how to extract metal above carbon

electrolysis of the molten compound

how to extract metal below carbon

displacement/ reduction using carbon

low grade ore

low % metal in ore

high grade ore

high % metal in ore

ores (3 bullet points)

• rocks containing metal compounds

• contain enough metal to make it economically viable to extract metal

• ores may be concentrated before metal is extracted

reduction with iron

carbon removes oxygen from iron (carbon gains oxygen- oxidation)