Menu
CoddyChemistry
Start learning

Bohr's Shells

Part of the Atomic Structure section of Coddy's Chemistry journey. Lesson 9 of 45.

In 1913 Niels Bohr said electrons move only in fixed shells around the nucleus, never in between.

The first shell holds 2 electrons, the second 8, the third 8 (for the first 20 elements). The inner shells fill first.

A carbon atom with 2 electrons in its first shell and 4 in its second, beside a sodium atom with 2, 8 and 1

Carbon (2, 4) and sodium (2, 8, 1): the inner shells fill first

Carbon, 6 electrons: 2, 4. Sodium, 11 electrons: 2, 8, 1. Neon, 10 electrons: 2, 8.

challenge icon

Challenge

A fluorine atom has 9 protons, so 9 electrons. Place its electrons in their shells.

Try it yourself

Electron shellsFill the electrons of F (fluorine)
quiz iconTest yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Atomic Structure

1Matter and Atoms

What Everything Is Made OfElements, Compounds, MixturesChemical SymbolsCounting Atoms in a FormulaRecap - Molecule Kit

4Electron Arrangement

Shells and the First 20Valence ElectronsIonization Energy as EvidenceLight from AtomsSubshells: s, p, dAufbau, Hund and PauliWriting ConfigurationsIons and the ExceptionsRecap - Configuration Race

7Practice Problems

Recap - Potassium OxideRecap - Helium from RocksRecap - Uranium to Lead

2Models of the Atom

Dalton and ThomsonRutherford's Gold FoilThe Nuclear AtomBohr's ShellsRecap - From Ball to Nucleus

5The Periodic Table

Mendeleev's PuzzleGroups and PeriodsBlocks: s, p, d, fMetals, Non-metals, MetalloidsAlkali MetalsHalogensNoble GasesRecap - Build the Table

3Inside the Atom

Protons Decide the ElementElectrons and ChargeNeutrons and Mass NumberNuclide NotationIonsIsotopesRadioactive DecayRelative Atomic MassRecap - Mystery Particles

6Periodic Trends

Atomic RadiusIonic RadiusIonization Energy TrendElectronegativityExplaining TrendsRecap - Mystery Element