Structure 1.3.1—Emission spectra are produced by atoms emitting photons when electrons in
excited states return to lower energy levels.

---

Structure 1.3.2—The line emission spectrum of hydrogen provides evidence for the existence of
electrons in discrete energy levels, which converge at higher energies

---

Structure 1.3.3—The main energy level is given an integer number, n, and can hold a maximum of
2n² electrons

---

Structure 1.3.4—A more detailed model of the atom describes the division of the main energy level
into s, p, d and f sublevels of successively higher energies.

---

Structure 1.3.5—Each orbital has a defined energy state for a given electron configuration and
chemical environment, and can hold two electrons of opposite spin.
Sublevels contain a fixed number of orbitals, regions of space where there is a high probability of
finding an electron.

---

Structure 1.3.6—In an emission spectrum, the limit of convergence at higher frequency corresponds
to ionization. AHL

---

Structure 1.3.7—Successive ionization energy (IE) data for an element give information about its
electron configuration. AHL

---

What You’ll Learn:

• Qualitatively describe the relationship between colour, wavelength, frequency, and energy across the electromagnetic spectrum.
• Distinguish between a continuous and a line spectrum.
• Describe the emission spectrum of the hydrogen atom, including the relationships between the lines and energy transitions to the first, second and third energy levels.
• The names of the different series in the hydrogen emission spectrum will not be assessed.
• Deduce the maximum number of electrons that can occupy each energy level.
• Recognize the shape and orientation of an s atomic orbital and the three p atomic orbitals.
• Apply the Aufbau principle, Hund’s rule and the Pauli exclusion principle to deduce electron configurations for atoms and ions up to Z = 36
• Full electron configurations and condensed electron configurations using the noble gas core should be covered.
• Orbital diagrams, i.e. arrow-in-box diagrams, should be used to represent the filling and relative energy of orbitals.
• The electron configurations of Cr and Cu as exceptions should be covered.

AHL Only

• Explain the trends and discontinuities in first ionization energy (IE) across a period and down a group.
• Calculate the value of the first IE from spectral data that gives the wavelength or frequency of the convergence limit.
• The value of the Planck constant h and the equations E = h f and c = λ f are given in the data booklet.
• Deduce the group of an element from its successive ionization data.
• Databases are useful for compiling graphs of trends in IEs