Electron configurationAQA A-Level Chemistry: Flashcards

What these 12 flashcards ask

How many electrons can one orbital hold?
How many orbitals are in an s, p and d sub-shell?
What is the maximum number of electrons in the s, p and d sub-shells?
State the filling order of sub-shells up to Z = 36.
Which fills first, 4s or 3d?
Write the electron configuration of Cr.
Write the electron configuration of Cu.
Why do Cr and Cu differ from the simple filling order?
From which sub-shell are electrons removed first when a transition metal forms an ion?
Write the electron configuration of Fe²⁺.
Write the electron configuration of Cl⁻.
How are electrons arranged in orbitals of the same sub-shell?

Exam questions on Electron configuration

Transition metal ions give many gemstones their colour. Ruby owes its red colour to Cr³⁺ ions in aluminium oxide, and a pale green mineral contains Fe²⁺ ions. The atomic numbers of chromium and iron are 24 and 26.
Write the full electron configuration of a Fe²⁺ ion, and state which sub-shell the electrons were removed from when the ion formed.2 marks
Semiconductor devices are made from p-block elements such as gallium (atomic number 31) and selenium (atomic number 34). A technician needs to know their electron configurations and those of their ions.
Write the full electron configuration of a gallium atom and explain why gallium is classed as a p-block element.2 marks
A student writes the ground-state electron configuration of titanium (atomic number 22) as 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁴, and states that when titanium forms ions the electrons are lost from the 3d sub-shell first. Vanadium has atomic number 23.
Identify the two errors in the student's statements, and write the correct ground-state electron configuration of titanium.3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).