Ionic Bonding Flashcards

All 16 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.

How are ionic bonds formed?

By the transfer of electrons from a metal atom to a non-metal atom, producing cations and anions.

What are the electronic configurations of the ions formed when sodium (2.8.1) reacts with chlorine (2.8.7)?

$\mathrm{Na^+}$ 2.8 and $\mathrm{Cl^-}$ 2.8.8

In a dot and cross diagram of an ionic compound, how is each ion shown?

e.g. sodium chloride

Each ion is drawn in square brackets with its charge outside, showing only the outer shell.

e.g. $[\mathrm{Na}]^+$ (no outer electrons shown) and $[\mathrm{Cl}\;\text{with 8 outer electrons}]^-$

Describe the structure of an ionic compound.

A giant lattice: a regular arrangement of ions held together by strong electrostatic forces (ionic bonds) between oppositely-charged ions.

True or false? In an ionic lattice, each ion is only attracted to the one ion it transferred electrons with.

False. The strong electrostatic forces act in all directions between all oppositely-charged ions in the lattice.

What does the ending –ate tell you about a compound's name?

It contains the named elements plus oxygen.

e.g. sodium sulfate contains sodium, sulfur and oxygen

What are the steps to deduce the formula of an ionic compound from its ions?

e.g. $\mathrm{Ti^{4+}}$ and $\mathrm{SO_4^{2-}}$

1. Write the charges: 4+ and 2−
2. Choose numbers of each ion so the total charge is zero: one $\mathrm{Ti^{4+}}$, two $\mathrm{SO_4^{2-}}$
3. Write as subscripts, brackets round a group ion taken more than once: $\mathrm{Ti(SO_4)_2}$

Give the formulae and charges of the hydroxide, nitrate, carbonate and sulfate ions.

$\mathrm{OH^-}$, $\mathrm{NO_3^-}$, $\mathrm{CO_3^{2-}}$, $\mathrm{SO_4^{2-}}$

True or false? The charges must be written in the final formula of an ionic compound.

False. The formula is written without charges, e.g. $\mathrm{Na_2SO_4}$, and the numbers must be subscripts.

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

What does the ending –ide tell you about a compound's name?

The compound contains only the elements named, with no extra oxygen. Hydroxide is the exception: it contains oxygen and hydrogen.

e.g. potassium bromide contains only potassium and bromine