Metals give electrons to non-metals, the charges that follow from the group number, dot and cross diagrams, and the formula of an ionic compound.
What you will learn
- Give the charge on an ion from its group
- Draw and read dot and cross diagrams for ionic compounds
- Work out the formula of an ionic compound and the number of each ion
Electrons move from metal to non-metal
When a metal reacts with a non-metal, the metal atoms lose their outer electrons and the non-metal atoms gain them.
Both end up with a full outer shell, like a noble gas.
Losing negative electrons leaves a positive ion. Gaining them makes a negative ion. The oppositely charged ions attract each other: that attraction is the ionic bond.
Sodium (2,8,1) gives its one outer electron to chlorine (2,8,7). The ions are Na+ (2,8) and Cl− (2,8,8). A dot and cross diagram uses dots for one atom's electrons and crosses for the other's, so you can see where each one came from.
The rest of this lesson and its 9 practice questions are locked.
In this lesson
- Electrons move from metal to non-metal
- The charge comes from the group
- Try it: Read the group, predict the ion
- Making the charges cancel
- Try it: Your first formula
9 practice questions, marked as you go; about 22 minutes in all.
Key terms
Lose, Gain, Positive ion, Negative ion, Ide
In this unit: Bonding, structure and the properties of matter
Ionic, covalent and metallic bonding, the structures they make, and how structure explains melting points, conduction and hardness, with nanoparticles for separate Chemistry.