OCR Chemistry A-Level – Module 1-4 Exam with Questions and Answers – 100%
Solved
an element in period 3 has the following successive ionisation energies, identify the element -
✔✔✔-the largest increase in ionisation energy is between fourth and fifth which indicates that
there are four outershell electrons and the fifth is being removed from a shell closer to the
nucleus.
between which type of molecules do intermolecular forces occur? - ✔✔✔-simple covalent
molecules
define a dative covalent bond - ✔✔✔-a shared pair of electrons which has been provided by
only one of the bonding atoms
define activation energy - ✔✔✔-the minimum energy required to start a reaction by the
breaking of bonds
define covalent bond - ✔✔✔-the strong electrostatic force of attraction between the shared
pair of electrons and the nuclei of the bonded atoms
define electronegativity - ✔✔✔-the ability of an atom to attract the bonding electrons in a
covalent bond
define first ionisation energy - ✔✔✔-the energy required to remove one electron from each
atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions
define ionic bond - ✔✔✔-the electrostatic force of attraction between positive and negative
ions
define molecular formula - ✔✔✔-the actual number of atoms of each element in a compound
define periodicity - ✔✔✔-the trend in properties that is repeated across a period
, OCR Chemistry A-Level – Module 1-4 Exam with Questions and Answers – 100%
Solved
define relative isotopic mass - ✔✔✔-the ass of an atom of an isotope of an element relative to
one twelfth the mass of an atom of C-12
define structural isomerism - ✔✔✔-compounds with the same molecular formula but different
structural formula
define what an orbital is - ✔✔✔-a region within an atom that can hold up to two electrons of
opposite spins
describe the cation test - ✔✔✔-NH4+ + OH- = NH3 + H2O
- add aqueous sodium hydroxide to ammonium ions
describe the qualitative tests in order - ✔✔✔-1. the carbonate test
- add dilute HNO3
- if solution bubbles then there are CO32- ions present
2. the sulfate test
- add excess Ba(NO3)2
- if white precipitate forms then SO42- ions are present
3. the halide test
- add AgNO3
- if precipitate (white, cream, yellow) forms then halide ions are present
give a use of calcium hydroxide - ✔✔✔-to neutralise acidic soils to maximise crop yields
give a use of magnesium hydroxide - ✔✔✔-to neutralise excess acids in the stomach
Solved
an element in period 3 has the following successive ionisation energies, identify the element -
✔✔✔-the largest increase in ionisation energy is between fourth and fifth which indicates that
there are four outershell electrons and the fifth is being removed from a shell closer to the
nucleus.
between which type of molecules do intermolecular forces occur? - ✔✔✔-simple covalent
molecules
define a dative covalent bond - ✔✔✔-a shared pair of electrons which has been provided by
only one of the bonding atoms
define activation energy - ✔✔✔-the minimum energy required to start a reaction by the
breaking of bonds
define covalent bond - ✔✔✔-the strong electrostatic force of attraction between the shared
pair of electrons and the nuclei of the bonded atoms
define electronegativity - ✔✔✔-the ability of an atom to attract the bonding electrons in a
covalent bond
define first ionisation energy - ✔✔✔-the energy required to remove one electron from each
atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions
define ionic bond - ✔✔✔-the electrostatic force of attraction between positive and negative
ions
define molecular formula - ✔✔✔-the actual number of atoms of each element in a compound
define periodicity - ✔✔✔-the trend in properties that is repeated across a period
, OCR Chemistry A-Level – Module 1-4 Exam with Questions and Answers – 100%
Solved
define relative isotopic mass - ✔✔✔-the ass of an atom of an isotope of an element relative to
one twelfth the mass of an atom of C-12
define structural isomerism - ✔✔✔-compounds with the same molecular formula but different
structural formula
define what an orbital is - ✔✔✔-a region within an atom that can hold up to two electrons of
opposite spins
describe the cation test - ✔✔✔-NH4+ + OH- = NH3 + H2O
- add aqueous sodium hydroxide to ammonium ions
describe the qualitative tests in order - ✔✔✔-1. the carbonate test
- add dilute HNO3
- if solution bubbles then there are CO32- ions present
2. the sulfate test
- add excess Ba(NO3)2
- if white precipitate forms then SO42- ions are present
3. the halide test
- add AgNO3
- if precipitate (white, cream, yellow) forms then halide ions are present
give a use of calcium hydroxide - ✔✔✔-to neutralise acidic soils to maximise crop yields
give a use of magnesium hydroxide - ✔✔✔-to neutralise excess acids in the stomach
