Chemistry higher C3 OCR

Module 3

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  • Created on: 01-01-12 12:44
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Atomic number is the bottom number of the element ·
Mass number is the top number of the element ·
Number of neutrons= Atomic number-Mass number ·
Number of protons=Number of electrons ·
-1 0.0005 0 Electron
1 +1 Neutron 1 Proton
Charge Mass
Electrons -Negative charge -They are in shells around the nucleus
Nucleus -Contains protons and neutrons -Positive charge
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Isotopes,elements and compounds
Definition of an isotope: Different atomic forms of the same element which have the same
number of protons but different number of neutrons ^Basically they have the same atomic number but different
mass number
Elements are made of only 1 type of atom -They can't be broken down easily
Compounds are chemically bonded-after the chemical reaction it's hard to separate elements
again -Properties of compound are different to the properties of the elements it was made from.
There are 2 types of chemical bonding: -Ionic bonding -Covalent bonding

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The maximum number of electrons in each shell is: 1st shell : 2 2nd shell: 8 3rd shell: 8
Electron configuration
an element has determines its period
Rows are called periods -Each period represents another full shell of electrons -Number of shells
outer shells -Elements in the same group have similar properties
determines its group -Elements in the same group have the same number of electrons in their
Vertical columns are called groups -Number of electrons an element has in its outer shell
The periodic…read more

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NaCl dissolves to form a solution that conducts electricity
form so they can carry a current
· They conduct electricity when molten because the ions are free to move when in molten
· They have high melting and boiling points due to strong chemical bonds
aren't free to move so when solid they don't conduct electricity -Very strong bonds between all ions
NaCl and MgO form giant lattices -Ionic bonds always produce giant ionic structures -The ions
Ions and ionic compounds
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6…read more

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Potassium=Lilac flame
Alkali metals burn with colours: Lithium=Red Flame Sodium=Yellow/orange flame
Example of reaction with water: 2Na+ 2H#O ===> 2NaOH + H#
Alkali metals continued
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Definition: Electrolysis is the breaking down of a substance using electricity -It needs a
liquid -the electrolyte- to conduct the electricity -Electrolytes are usually free ions dissolved in water
which are the things that conduct electricity
· In electrolysis electrons are taken away from ions at the positive anode and given to other…read more

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OH# ====>2H#O + O# + 4e# 2H# + 2e# ====> H# Anode Cathode
Learn these off by heart:
2 water molecules
· At the anode , 4 Hydroxide ions lose their electrons and become 1 oxygen molecule and
· At the cathode , 2 Hydrogen ions accept 2 electrons to become 1 Hydrogen molecule
Electrolysis continued
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Extracting Aluminium
· Electrolysis removes aluminium form its ore
· Pure aluminium oxide (Al#O#) is found in Bauxite
· Aluminium is more reactive…read more

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· Electrolysis uses a lot of electricity,lots of energy is needed and the cathode needs to be
-Decomposition of aluminium oxide= Aluminium oxide =====> Aluminium+Oxygen
(Oxidation) 2O2# ======>O + 4e At the anode:
(Reduction) + 3e# =====> Al At the cathode
· It's a redox reaction because reduction and oxidation are happening at the same time
· As the Carbon anode is constantly being worn down it often needs replacing
Extracting Aluminium continued
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Covalent Bonding
Covalent bonding is when…read more

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Cl# + 2KI ====> I# + 2KCl Cl# + 2KBr ====> Br# + 2KCl
More reactive halogens displace less reactive ones
2Na + 2Cl# ====> 2NaCl 2K + 2Br# ======> 3KBr#
Halogens react with alkali metals to form salts
Halogens continued
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· Group 7 elements are the Halogens
· Fluorine,Chlorine,Bromine,Iodine and Astatine
· All have 7 electrons in their outer shell
· As you go down group 7 the halogens become less reactive because there's less
inclination to…read more

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of electricty,easily bent Aluminium-Aeroplanes-Low density,Strong,Doesn't corrode Steel/Iron-
Stainless steel-saucepans-Good conductor of heat Copper-Electrical wiring-Good conductor
Good conductors of heat and electricity ·
Malleable ·
High tensile strength ·
Strong metallic bonding ·
Strong attractions between the free electrons ·
Shiny ·
High density ·
High melting and boiling points ·
These bonds allow the outer electrons of each atom to move freely Properties of metals: ·
Metals consist of a giant structure of atoms held together with metallic bonds ·
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Copper compounds are blue
· Iron III compounds are orange
· Iron II compounds are light green
They have colourful compounds:
ammonia 2)Nickel is used for the hydrogenation of alkenes
· They make good catalysts: 1) Iron is the catalyst used in Haber process for making
They are found in the middle section of the periodic table
Transition metals
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Thermal decomposition
Definition: When a substance breaks down into at least 2 other substances by heat
Transition metal carbonates break…read more

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Definition:A percipitation reaction is where 2 solutions react and an insoluble solid forms in the solid
CuSO# + 2NaOH ===> Cu(OH)# + Na#SO#
Or this can be written as an ionic equation
Cu2 + 2OH ====> Cu(OH)
· Copper Hydroxide is a blue solid
· Iron II Hydroxide is a dark grey solid
· Iron III Hyrdoxide is an orange solid…read more


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