Ions

An atom that loses electrons has more protons than electrons and becomes a positive ion; one that gains electrons becomes a negative ion. The element stays the same, since the protons don't change, and the charge is written top right of the symbol: Na⁺, Cl⁻. Sodium, with one lone outer electron, gives it to chlorine, which is one short of eight; the opposite charges then hold the ions together in table salt. Ions do jobs in the body too, carrying nerve signals and building bone.

Depth 1 · Foundation

You can say whether an atom that gains or loses electrons becomes a positive or negative ion, work out an ion's charge from its protons and electrons, and explain how sodium and chlorine make table salt.

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Depths of understanding

1
Foundation
You can say whether an atom that gains or loses electrons becomes a positive or negative ion, work out an ion's charge from its protons and electrons, and explain how sodium and chlorine make table salt.
Opens after
Atom, depth 2Which electrons an atom gives or takes depends on how its shells are filled.Atomic numberAn ion's charge comes from comparing its electrons with its protons.
2
Deeper
You can explain why solutions of ionic compounds conduct electricity and solutions of molecular ones don't, tell an ionic compound from a molecular one by a conductivity test, and say what sodium and iron ions do in the body.
Master depth 1 first
Electrical conductors and insulators, depth 2A solution conducts only if it has charged particles free to move.SolutionsThe test is done on solutions: the substance is dissolved in water first.

Your path here

What's still between you and Ions, depth 1, in the order you can learn it.

Where it fits

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AtomDepth 2 Atomic number

This concept

IonsAtoms and Elements

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Ionic bondsChemical Bonding

Builds onThis conceptOpens upAtomDepth 2 Atomic number IonsAtoms and Elements Ionic bondsChemical Bonding