Advanced Higher Chemistry Unit 1:
Physical & Inorganic chemistry
What happens to electrons in a substance when a photon is absorbed or emitted? -
ANS-Energy is gained or lost by the electrons in the substance
What is the energy a photon carries proportional to? - ANS-A photon carries quantised energy
proportional to the frequency of radiation
What is required in terms of energy for an electron to be promoted to a higher energy level
when energy is absorbed by an atom? - ANS-The energy absorbed must be equivalent to the
difference in energy between the energy levels
What do absorption and emission spectra show us? - ANS-The identification and quantity of
elements in a sample
Explain the process of atomic emission spectroscopy - ANS-- A sample is heated
- When energy is transferred to atoms, electrons within the atoms may be promoted to higher
energy levels.
- The electrons absorb energy, moving to an excited state
- They then fall back to ground state and emit a photon of light
- These photons of light can be gathered through a slit and can be passed through a prism
- This will split up the different wavelengths of light to create a spectrum made up of series of
lines at discrete (quantised) energy levels
- A different wavelength is emitted for each transition and is seen as a separate line on the
spectrum
- The more intense the light emitted the larger the sample is
Explain the process of absorption spectroscopy - ANS--Electromagnetic radiation is directed at
an atomised sample
- Radiation is absorbed as electrons are promoted to higher energy levels
- The electrons become excited by the absorption of specific photons
- The spectrum is produced by measuring how the intensity of the light varies
- Absorption spectra appears as black lines missing from a full spectrum. This is because the
wavelengths of these photons are missing from the full spectrum
What is the term used to describe the fixed energy of electrons within atoms? - ANS-Quanta
What do the lines on absorption/emission spectra represent? - ANS-The difference in energy
between the energy levels, each electron transition causes a separate line on the spectrum
, Why do different elements produce different absorption/emission spectra? - ANS-Since they
have different electron configurations and these electrons are attracted to the nucleus of the
atoms by differing numbers of protons
How can the concentration of an element be determined using atomic spectroscopy? - ANS-By
the intensity of light emitted or absorbed
Why do some elements/compounds produce no colour when subjected to high voltage/put in a
bunsen burner? - ANS-The energy supplied is not sufficient enough to promote electrons to an
excited state or the light emitted in not in the visible region of the ES.
Describe the purpose of each of the quantum numbers - ANS-Principal quantum number (n):
indicates main energy level for an electron and is related to the size of the orbital
Angular momentum quantum number (l): determines the shape of the subshell
Magnetic quantum number (ml): determines the orientation of the orbital
Spin magnetic quantum number (ms): determines the direction of spin
Describe the quantum number laws - ANS-l= has values from 0 to n-1
ml= has values from -l to +l
ms= has values from +1/2 to -1/2
Define aufbau principle - ANS-Electrons fill orbitals in order of increasing energy
Define the Pauli exclusion principle - ANS-No two electrons in one atom can have the same set
of four quantum numbers, therefore, no orbital can hold more than two electrons and these two
electrons must have opposite spins
Define Hund's rule - ANS-When degenerate orbitals are available, electrons fill each singly,
keeping their spins parallel before spin pairing starts
What transition metals don't follow the aufbau principle in the filling of their d orbitals and why? -
ANS-Chromium and copper- this is because they have a special ability associated with their
d-subshells being half-filled or completely filled
Explain the different trends in ionisation energies - ANS-Subshells that are higher in energy
have higher ionisation energies. Half-filled or full subshells are harder to remove since they are
more stable, hence why they have higher ionisation energies
Why does nitrogen have a higher ionisation energy that oxygen? - ANS-Nitrogen has a
half-filled 2p subshell which is more stable than the 4 electrons occupying the 2p subshell in
oxygen, therefore making the outer electron from oxygen easier to remove
Describe how to calculate the number of electron pairs surrounding a central atom - ANS-- Take
the total number of valence (outer) electrons on the central atom
Physical & Inorganic chemistry
What happens to electrons in a substance when a photon is absorbed or emitted? -
ANS-Energy is gained or lost by the electrons in the substance
What is the energy a photon carries proportional to? - ANS-A photon carries quantised energy
proportional to the frequency of radiation
What is required in terms of energy for an electron to be promoted to a higher energy level
when energy is absorbed by an atom? - ANS-The energy absorbed must be equivalent to the
difference in energy between the energy levels
What do absorption and emission spectra show us? - ANS-The identification and quantity of
elements in a sample
Explain the process of atomic emission spectroscopy - ANS-- A sample is heated
- When energy is transferred to atoms, electrons within the atoms may be promoted to higher
energy levels.
- The electrons absorb energy, moving to an excited state
- They then fall back to ground state and emit a photon of light
- These photons of light can be gathered through a slit and can be passed through a prism
- This will split up the different wavelengths of light to create a spectrum made up of series of
lines at discrete (quantised) energy levels
- A different wavelength is emitted for each transition and is seen as a separate line on the
spectrum
- The more intense the light emitted the larger the sample is
Explain the process of absorption spectroscopy - ANS--Electromagnetic radiation is directed at
an atomised sample
- Radiation is absorbed as electrons are promoted to higher energy levels
- The electrons become excited by the absorption of specific photons
- The spectrum is produced by measuring how the intensity of the light varies
- Absorption spectra appears as black lines missing from a full spectrum. This is because the
wavelengths of these photons are missing from the full spectrum
What is the term used to describe the fixed energy of electrons within atoms? - ANS-Quanta
What do the lines on absorption/emission spectra represent? - ANS-The difference in energy
between the energy levels, each electron transition causes a separate line on the spectrum
, Why do different elements produce different absorption/emission spectra? - ANS-Since they
have different electron configurations and these electrons are attracted to the nucleus of the
atoms by differing numbers of protons
How can the concentration of an element be determined using atomic spectroscopy? - ANS-By
the intensity of light emitted or absorbed
Why do some elements/compounds produce no colour when subjected to high voltage/put in a
bunsen burner? - ANS-The energy supplied is not sufficient enough to promote electrons to an
excited state or the light emitted in not in the visible region of the ES.
Describe the purpose of each of the quantum numbers - ANS-Principal quantum number (n):
indicates main energy level for an electron and is related to the size of the orbital
Angular momentum quantum number (l): determines the shape of the subshell
Magnetic quantum number (ml): determines the orientation of the orbital
Spin magnetic quantum number (ms): determines the direction of spin
Describe the quantum number laws - ANS-l= has values from 0 to n-1
ml= has values from -l to +l
ms= has values from +1/2 to -1/2
Define aufbau principle - ANS-Electrons fill orbitals in order of increasing energy
Define the Pauli exclusion principle - ANS-No two electrons in one atom can have the same set
of four quantum numbers, therefore, no orbital can hold more than two electrons and these two
electrons must have opposite spins
Define Hund's rule - ANS-When degenerate orbitals are available, electrons fill each singly,
keeping their spins parallel before spin pairing starts
What transition metals don't follow the aufbau principle in the filling of their d orbitals and why? -
ANS-Chromium and copper- this is because they have a special ability associated with their
d-subshells being half-filled or completely filled
Explain the different trends in ionisation energies - ANS-Subshells that are higher in energy
have higher ionisation energies. Half-filled or full subshells are harder to remove since they are
more stable, hence why they have higher ionisation energies
Why does nitrogen have a higher ionisation energy that oxygen? - ANS-Nitrogen has a
half-filled 2p subshell which is more stable than the 4 electrons occupying the 2p subshell in
oxygen, therefore making the outer electron from oxygen easier to remove
Describe how to calculate the number of electron pairs surrounding a central atom - ANS-- Take
the total number of valence (outer) electrons on the central atom
