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AQA Chemistry As Level Paper 1 Exam 2024/2025 Questions With Completed Solutions.
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AQA Chemistry As Level Paper 1 Exam 2024/2025 Questions With Completed Solutions.
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AQA Chemistry As Level Paper 1State the electron rules - ANS Lowest energy filled first (3d>4s)
Line up parallel
Single until forced to pair
Electronegativity - ANS The ability of an atom to attract electrons within a covalent bond
RAM (relative atomic mass) - ANS Average mass of one atom compared to 1/12th the mass of
a c-12 atom
-
Ionization energy - ANS The energy required to remove one mole of electrons from each of one
mole of gaseous atoms to form one mole of positive gaseous ions
(Endothermic)
Trends of Ionisation Energy - ANS Across a period, i.e increases as there is no increase in
shielding but an increase in atomic number
Decrease down a group due to increased shielding reducing the electrostatic force of attraction
from the nucleus
Drop at 2,3 - ANS Al - Between groups 2,3... first electron in p orbital
- increase in shielding
- reduce forces of attraction
- less energy required to remove
Drop at 4,5 - ANS P - between groups 4-5 there is a drop
- First electron pairing
- increased repulsion
- less energy is required to remove an eleccte
Isotopes - ANS Atoms with the same atomic number but a different mass number
- do not react differently as same electron configuration
Factors Affecting I.E - ANS -Atomic Radius
-Shielding
-Effective Nuclear Charge
-Proton Number
Not 100% yield because... - ANS Incomplete Reactions
Unwanted side reactions
Products lost as gases
, Ice less dense than water - ANS Water - hydrogen bonds continuously broken and reformed
Ice - hydrogen bonds kept in a fixed position so are slightly longer
Increased distance causes ice to be less dense and float
Enthalpy - ANS Measure of heat content of a substance under constant conditions
Endothermic reaction - ANS Heat is given off
Negative enthalpy
Bond making - releasing energy
Combustion/ Respiration
Endothermic Reaction - ANS Heat energy taken in
Positive Enthalpy
Bond breaking requires energy
Photosynthesis/ Thermal Decomposition
Calculating Enthalpy Change - ANS Reactants - Products
Or
KJ^-1mol
Q=MCAT
Divided by moles
Hess's Law - ANS Enthalpy change is independent of the route taken
Formation
Combustion
Standard Enthalpy change of combustion - ANS Enthalpy change when one mole of a
substance undergoes complete combustion under constant conditions
Standard Enthalpy change of formation - ANS Enthalpy changed when one mole of a substance
is formed from its reactants under constant conditions
Standard Enthalpy change of neutralisation - ANS Enthalpy change when one mole of water is
formed from its ions in solution
Mean bond Enthalpy/ Bond disassociation - ANS Energy required to break one mole of gaseous
bonds to form gaseous atoms
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