AQA C3 Chemistry

All Chemistry Unit C3 toppics included. Brief but thorough notes.

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C3 Chemistry
End of 20th century ­ protons electrons found
Elements arranged by atomic numbers (little) in groups
Similar chemical properties cause atoms have same number of electrons in outer shell
Reactivity of element depends on total number of electrons
Atoms get larger > electrons in outer shell less strongly attracted to nucleus
Metals react > lose electrons > reactivity of metals in a group increases going down the group
Non-metals react > gain electrons > decreases reactivity, going down in a group
GROUP 1 ­ Alkali metals
Reactive metals
Soft solids at room temp > low mpt/bpt > decrease going down the group
Low densities > float
React with air and water > water produce hydrogen gas and strong alkali
All have on electron in outer shell
More reactive going down the group
REACTIVITY INCREASES: outer electron = less strongly attracted to nucleus as number of occupied energy
levels increase and atoms get larger
React with halogens to form salts = white/colourless
KEY POINTS:
Elements in group 1 all metals that form positive ions with a charge of 1+
Going down the group: reactivity increases + mpt/bpt decrease
Only form ionic compounds in which their ions have only 1+ (single positive charge)
GROUP 7 ­ Halogens
Non metallic elements in group 7
Exist as small molecules made up by pairs of atoms
Low mpt/bpt increase down the group
Room temp: fluorine = pale yellow gas, chlorine = green gas, bromine = red-brown liquid, iodine = grey solid
(vaporises into violet gas)
7 electrons in outer shell
Form ionic compounds with metals
Ions have charge of -1
Bond covalently with non-metals forming molecules
Reactivity decreases going down the group because attraction of outer electron to nucleus decreases as
number of occupied energy levels increases
HALOGENS FORM IONIC COMPOUNDS WITH METALS AND COVALENT BONDS WITH NON-METALS
More reactive halogen able to displace a less reactive halogen from its compounds in solution
KEY POINTS:
All non-metals with low mpt/bpt
Form compounds with non/metals
Reactivity decreases going up the group
Transition Elements
Between groups 2 and 3
All metals (except mercury) have higher bpt/mpt than alkali metals
Strong, dense, useful building material, often as alloys
Malleable
Ductile

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Good conductors
React barely with water/oxygen (air)
Form positive ions with various charges
Different charges on ions arise: small number of electrons in outer shell and an incomplete inner shell
Lower energy level can hold up to ten more electrons for elements beyond calcium
Compounds often brightly coloured
Many transition metals and their compounds are catalysts for chemical reactions
KEY POINTS:
Between groups 2/3
All metals with high densities
Form several different ions
Form coloured compounds
Used as catalysts
Strong and Weak Alkali's
When acids…read more

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Titration Calculations
Used to find the volumes of solutions that react exactly:
o If the conce of one solution is known, the volumes that react together are known, the conce of the
other solution can be calculated
o This info can be used to find the amount of a substance in a sample.
o Concentrations are calculated using balanced equations and moles
EG. TO FIND THE MISSING CONCENTRATION
NaOH + HCl NaCl + H2O
22.0cm3 25.0cm3 VOLUME
0.…read more

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Strontium > Stop
Calcium > teeth
Barium > bean (pea, green)
Sodium > Sun
LCCSSBP
HEATING ZINC COPPER (2) CARBONATE
Heat in ignition tube , see if limewater turns due to carbon
ZINC ­ White Yellow
COPPER ­ Turquoise Black
ANIONS
CHLORIDE BROMIDE IODIDE test with Ag+ (silver nitrate solution)
SULPHATE CARBONATE test with Barium Chloride and Dilute hydrochloric Acid
Chloride ­ white precipitate
Iodide ­ Pale yellow precipitate
Bromide ­ Cream precipitate
Carbonate ­ white substance fizzes
Sulphate ­ White precipitate > insoluble salt…read more

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Good for bones/teeth due to calcium
DISADV:
o Produces limescale
o Blocks pipes
o Makes heating less efficient
o Waste soap or buy softeners
PREVENT:
o CALGON ­ binds to calcium, can't interact with soap
o WASHING SODA (sodium carbonate) ­ precipitates out the calcium as CaCO3
o DISTILLATION ­ removes all dissolved compounds (expensive)
o ION EXCHANGE ­ Sodium replaces calcium ions
SOLUBILITY IN WATER
Temperature:
o Solids ­ more soluble at higher temp
o Gases less soluble at higher temp, more soluble at…read more

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