Ions Flashcards

All 6 cards in this deck

What is an ion?

An atom or group of atoms with a positive or negative charge.

What charge does an ion formed by a Group 1, 2, 6 or 7 element have?

e.g. magnesium (Group 2) and oxygen (Group 6)

Group 1: 1+, Group 2: 2+, Group 6: 2−, Group 7: 1−.

e.g. $\mathrm{Mg^{2+}}$ and $\mathrm{O^{2-}}$

How do you find the number of electrons in a simple ion from its atomic number and charge?

electrons = atomic number − charge, so a 1− ion has one more electron than protons and a 2+ ion has two fewer. Protons and neutrons are found as for the atom.

True or false? When an atom forms an ion, its number of protons changes.

False. Only electrons are lost or gained; the number of protons (and neutrons) stays the same.

What is the difference between a cation and an anion, and how is each formed from an atom?

A cation is a positive ion, made when an atom loses electrons. An anion is a negative ion, made when an atom gains electrons.

e.g. $\mathrm{K^+}$ is a cation, $\mathrm{S^{2-}}$ is an anion

Why do atoms of Group 1, 2, 6 and 7 elements lose or gain electrons to form ions?

To end up with a full outer shell, the same electronic configuration as a noble gas.

e.g. $\mathrm{S}$ (2.8.6) gains 2 electrons to become $\mathrm{S^{2-}}$ (2.8.8), like argon