S1.3 Electron Configurations

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

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

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

• 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.

• 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.

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

Inquiry 2—In the study of emission spectra from gaseous elements and of light, what qualitative and quantitative data can be collected from instruments such as gas discharge tubes and prisms?

Nature of science, Structure 1.2—How do emission spectra provide evidence for the existence of different elements?

Structure 3.1—How does an element’s highest main energy level relate to its period number in the periodic table?

Structure 3.1—What is the relationship between energy sublevels and the block nature of the periodic table?

(AHL) Structure 3.1—How does the trend in IE values across a period and down a group explain the trends in properties of metals and non-metals?

(AHL) Nature of science, Tool 3, Reactivity 3.1—Why are log scales useful when discussing [H+] and IEs?

(AHL) Structure 3.1—How do patterns of successive IEs of transition elements help to explain the variable oxidation states of these elements?