CCEA A-Level Chemistry 1110
Formulae, Equations and Amounts of Substance
Atomic Structure
Bonding
Intermolecular Forces and Structure
Shapes of Molecules and Ions
Redox
The Halogens
Acid-Base Titrations
Qualitative Tests
Formulae and Amounts of a Substance
Nomenclature and Isomerism in Organic Chemistry
Alkanes
Alkenes
Halogenoalkanes
Alcohols
Infrared Spectroscopy
Energetics
Kinetics
Equilibrium
Group II Elements and Their Compounds
Lattice Enthalpy, Entropy and Free Energy
Rates of Reaction
Equilibrium and Acid-Base Equilibria
Isomerism
Aldehydes and Ketones
Carboxylic Acids
Derivatives of Carboxylic Acids
Aromatic Chemistry
Spectroscopy and Chromatography
Volumetric Analysis
Transition Metals
Electrode Potentials
Amines
Amides and Polymers
Amino Acids and Proteins
Atomic Structure
Electronic configuration and the building up principle
- 3 things to know
- Unit AS 1
Overview
Building up principle and hund's rule for filling a subshell.
What you need to know
Answer each one before you reveal it.
Give the order in which the subshells are filled up to krypton.
How many electrons can be held in the s, p and d subshells?
Questions from this subtopic
Each one with the model answer underneath.
- 1
State the building up principle.
Model answer
The building up principle states that electrons occupy the lowest energy orbital available before any higher energy orbital is filled.
- 2
Give the order in which the subshells are filled up to krypton.
Model answer
The order is 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p.
- 3
How many electrons can be held in the s, p and d subshells?
Model answer
An s subshell holds 2 electrons, a p subshell holds 6 and a d subshell holds 10.
- 4
Why is the 4s subshell filled before the 3d subshell?
Model answer
The 4s subshell lies at a slightly lower energy than the 3d subshell when both are empty, so electrons enter 4s first.
- 5
Write the full electronic configuration of a calcium atom.
Model answer
The configuration is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s².
- 6
Write the full electronic configuration of a bromine atom.
Model answer
The configuration is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁵.
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