Topic 12.1: Atomic structure – Electrons in atom
The quantized nature of energy transitions is related to the energy states of electrons in atoms and molecules.
• Understanding: In an emission spectrum, the limit of convergence at higher frequency corresponds to the first ionization energy.
▪ Limit of convergence in an emission spectrum: frequency of the limit of converge can be used to determine ionization enthalpy.
• Understanding: Trends in first ionization energy across periods account for the existence of main energy levels and sub-levels in
atoms.
• Applications and skills: Explanation of the trends and discontinuities in first ionization energy across a period.
▪ Discontinuity trends in first ionization energy across periods accounts for main energy levels
and sub-levels in an atom
▪ Trends in first ionization energy across period
• Overall trend: as atomic number increases, the nuclear charge increases and atomic
radii decreases to attract valence electrons stronger
• Discontinuity: it is more difficult to remove electrons in full or half-full stable
orbitals
▪ Example: Be has a higher IE than B as 2s2 is a stable arrangement
• Understanding: Successive ionization energy data for an element give information that shows relations to electron configurations.
▪ Trends in successive ionization energy of an element
• Overall trend: successive ionization energy of an element increases with the
ionization number as it becomes increasingly difficult to remove electrons
from increasingly positive ions according to Coulomb’s law
• Large “jumps”: large jump from ionization energy is associated with
removal of electrons energy levels of different principal quantum number (n)
▪ The presence of large “jumps” in energy required for successive ionization is the reason
why all elements have a stable ionization state (i.e. Ti does not have a +5 state due to a
large jump in IE going from IE4 to IE5)
• Applications and skills: Solving problems using 𝐸 = ℎ𝑣.
▪ 𝐸 = ℎ𝑣 (Plank’s constant | h=6.626 x 10-34 J s)
▪ 𝑐 = 𝑣𝜆 (Speed of light | c=2.998 x 108 m s-1)
▪ Process of solving problems using E=hv
▪ Identify constants h, c
▪ Identify available parameter (e.g. E, h or c)
▪ Determine required parameter through substitution
• Applications and skills: Calculation of the value of the first ionization energy from spectral data which gives the wavelength or
frequency of the convergence limit.
ℎ𝑐
▪ If given wavelength (𝜆): 𝐸 =
𝜆
▪ If given frequency (v): 𝐸 = ℎ𝑣
• Applications and skills: Deduction of the group of an element from its successive ionization energy data.
▪ Process of deducing element from successive ionization energy data
• Identify the “big jumps” in the successive ionization energy
• From that, identify the group consisting of ions before the corresponding “big jump”
• Nature of science: Experimental evidence to support theories—emission spectra provide evidence for the existence of energy levels.
• International-mindedness: In 2012 two separate international teams working at the Large Hadron Collider at CERN independently
announced that they had discovered a particle with behaviour consistent with the previously predicted “Higgs boson”.
• Utilization: Electron microscopy has led to many advances in biology, such as the ultrastructure of cells and viruses. The scanning
tunnelling microscope (STM) uses a stylus of a single atom to scan a surface and provide a 3-D image at the atomic level.
• Guidance: The value of Planck’s constant (h) and 𝐸 = ℎ𝑣 are given in the data booklet in sections 1 and 2.
• Guidance: Use of the Rydberg formula is not expected in calculations of ionization energy.
The quantized nature of energy transitions is related to the energy states of electrons in atoms and molecules.
• Understanding: In an emission spectrum, the limit of convergence at higher frequency corresponds to the first ionization energy.
▪ Limit of convergence in an emission spectrum: frequency of the limit of converge can be used to determine ionization enthalpy.
• Understanding: Trends in first ionization energy across periods account for the existence of main energy levels and sub-levels in
atoms.
• Applications and skills: Explanation of the trends and discontinuities in first ionization energy across a period.
▪ Discontinuity trends in first ionization energy across periods accounts for main energy levels
and sub-levels in an atom
▪ Trends in first ionization energy across period
• Overall trend: as atomic number increases, the nuclear charge increases and atomic
radii decreases to attract valence electrons stronger
• Discontinuity: it is more difficult to remove electrons in full or half-full stable
orbitals
▪ Example: Be has a higher IE than B as 2s2 is a stable arrangement
• Understanding: Successive ionization energy data for an element give information that shows relations to electron configurations.
▪ Trends in successive ionization energy of an element
• Overall trend: successive ionization energy of an element increases with the
ionization number as it becomes increasingly difficult to remove electrons
from increasingly positive ions according to Coulomb’s law
• Large “jumps”: large jump from ionization energy is associated with
removal of electrons energy levels of different principal quantum number (n)
▪ The presence of large “jumps” in energy required for successive ionization is the reason
why all elements have a stable ionization state (i.e. Ti does not have a +5 state due to a
large jump in IE going from IE4 to IE5)
• Applications and skills: Solving problems using 𝐸 = ℎ𝑣.
▪ 𝐸 = ℎ𝑣 (Plank’s constant | h=6.626 x 10-34 J s)
▪ 𝑐 = 𝑣𝜆 (Speed of light | c=2.998 x 108 m s-1)
▪ Process of solving problems using E=hv
▪ Identify constants h, c
▪ Identify available parameter (e.g. E, h or c)
▪ Determine required parameter through substitution
• Applications and skills: Calculation of the value of the first ionization energy from spectral data which gives the wavelength or
frequency of the convergence limit.
ℎ𝑐
▪ If given wavelength (𝜆): 𝐸 =
𝜆
▪ If given frequency (v): 𝐸 = ℎ𝑣
• Applications and skills: Deduction of the group of an element from its successive ionization energy data.
▪ Process of deducing element from successive ionization energy data
• Identify the “big jumps” in the successive ionization energy
• From that, identify the group consisting of ions before the corresponding “big jump”
• Nature of science: Experimental evidence to support theories—emission spectra provide evidence for the existence of energy levels.
• International-mindedness: In 2012 two separate international teams working at the Large Hadron Collider at CERN independently
announced that they had discovered a particle with behaviour consistent with the previously predicted “Higgs boson”.
• Utilization: Electron microscopy has led to many advances in biology, such as the ultrastructure of cells and viruses. The scanning
tunnelling microscope (STM) uses a stylus of a single atom to scan a surface and provide a 3-D image at the atomic level.
• Guidance: The value of Planck’s constant (h) and 𝐸 = ℎ𝑣 are given in the data booklet in sections 1 and 2.
• Guidance: Use of the Rydberg formula is not expected in calculations of ionization energy.
