A-Level Edexcel Chemistry questions and
answers
how to test for C=C - decolourises bromine water
Atomic Number - number of protons in the nucleus of an atom of that element.
Mass Number - the sum of protons and neutrons in a nuclues of an atom
Isotopes - atoms of the same elementwith the same numberof protons but
different nuber of neutrons
Relative Atomic Mass - the average mass of an atom of an element compared to a
twelfth of the mass of an atom of carbon-12.
Relative Isotopic Mass - The mass of an atom of an isotope compared to one-
twelfth of the mass of an atom of carbon-12
Quantum Shell - the energy level of an electron.
Orbital - a region around the nucleus that can hold up to two electrons with
opposite spins.
,A-Level Edexcel Chemistry questions and
answers
What shape is the S orbital - spherical
What shape is the P orbital - dumbell
First Ionisation Energy - the measure of energy is needed to completely remove
one mole of electron from one mole of gaseous atom
Second Ionisation Energy - is a measure of energy needed to remove one-mole of
electron from one mole of gaseous ion
Periodicity - A repeating trend in the properties of the elements across the
periodic table
Why are copper and chromium important to do with filling up their subshells? -
because they have a half-filled subshell. This gives added stability so minimises
electron repulsion
,A-Level Edexcel Chemistry questions and
answers
Why is the first ionisation energy the lowest? - it is the lowest because the
electron is further away from the nucleus so less attraction and more shielding by
the inner electrons. This means less energy is needed to remove the electron.
Why does ionisation energy increase as you go across the period? - as you go
across the periodic table there are more protons so more attraction to the
electrons so decreasing atomic radii. This increases the ionisation energy.
first ionisation energy for sodium - see pic
Why does ionisation energy increase from Na to Mg - ionisation energy increases
becasue magnesium has more protons so more attraction to the electron
Why does ionisation energy decrease from Mg to Al - because the electron being
removed is from a new subshell. This means the electron is futher away from the
nucleus so less attraction to the nucleus.
Why does ionisation energy decrease from P to S - There are more electrons in the
same orbital so more repulsion.
, A-Level Edexcel Chemistry questions and
answers
What is the trend in ionisation energy as you go down the period? - As you go
down periods the electros get further away from the nucleus and atomic radii
increases. This means there is more shielding by inner electrons.
Why does successive ionisation energy increase? - because as you remove an
electron the ratio of proton to electron increases. This means more attraction and
so more energy needed to remove electrons.
Explain the stages of mass spectrometer. - Vapourisation- the sample is heated to
produce gaseous atom.
Ionisation- an electron gun is used to knock off electrons from the sample.
Acceleration- the speed is increased to make deflection easier.
Deflection- sample is deflected by electromagnet
Detector- the sample is detected by detector.
Why is fluorine the most reactive element - because it has 7 protons which are
pulling the electron so it is harder to lose electrons
Decribe the trend in reactivity as you go down group 1 - as you go down group
one
answers
how to test for C=C - decolourises bromine water
Atomic Number - number of protons in the nucleus of an atom of that element.
Mass Number - the sum of protons and neutrons in a nuclues of an atom
Isotopes - atoms of the same elementwith the same numberof protons but
different nuber of neutrons
Relative Atomic Mass - the average mass of an atom of an element compared to a
twelfth of the mass of an atom of carbon-12.
Relative Isotopic Mass - The mass of an atom of an isotope compared to one-
twelfth of the mass of an atom of carbon-12
Quantum Shell - the energy level of an electron.
Orbital - a region around the nucleus that can hold up to two electrons with
opposite spins.
,A-Level Edexcel Chemistry questions and
answers
What shape is the S orbital - spherical
What shape is the P orbital - dumbell
First Ionisation Energy - the measure of energy is needed to completely remove
one mole of electron from one mole of gaseous atom
Second Ionisation Energy - is a measure of energy needed to remove one-mole of
electron from one mole of gaseous ion
Periodicity - A repeating trend in the properties of the elements across the
periodic table
Why are copper and chromium important to do with filling up their subshells? -
because they have a half-filled subshell. This gives added stability so minimises
electron repulsion
,A-Level Edexcel Chemistry questions and
answers
Why is the first ionisation energy the lowest? - it is the lowest because the
electron is further away from the nucleus so less attraction and more shielding by
the inner electrons. This means less energy is needed to remove the electron.
Why does ionisation energy increase as you go across the period? - as you go
across the periodic table there are more protons so more attraction to the
electrons so decreasing atomic radii. This increases the ionisation energy.
first ionisation energy for sodium - see pic
Why does ionisation energy increase from Na to Mg - ionisation energy increases
becasue magnesium has more protons so more attraction to the electron
Why does ionisation energy decrease from Mg to Al - because the electron being
removed is from a new subshell. This means the electron is futher away from the
nucleus so less attraction to the nucleus.
Why does ionisation energy decrease from P to S - There are more electrons in the
same orbital so more repulsion.
, A-Level Edexcel Chemistry questions and
answers
What is the trend in ionisation energy as you go down the period? - As you go
down periods the electros get further away from the nucleus and atomic radii
increases. This means there is more shielding by inner electrons.
Why does successive ionisation energy increase? - because as you remove an
electron the ratio of proton to electron increases. This means more attraction and
so more energy needed to remove electrons.
Explain the stages of mass spectrometer. - Vapourisation- the sample is heated to
produce gaseous atom.
Ionisation- an electron gun is used to knock off electrons from the sample.
Acceleration- the speed is increased to make deflection easier.
Deflection- sample is deflected by electromagnet
Detector- the sample is detected by detector.
Why is fluorine the most reactive element - because it has 7 protons which are
pulling the electron so it is harder to lose electrons
Decribe the trend in reactivity as you go down group 1 - as you go down group
one
