S4.6.6 For the adult
Ionic bonding
Why does salt stay solid in a pan that is hot enough to boil water dry?
What this chapter teaches
In ionic bonding a metal atom gives electrons to a non-metal atom, and the two ions attract. They form a giant lattice, so an ionic compound melts at a high temperature and conducts only when molten or dissolved.
Three questions to ask
There is no one right wording. Listen for the idea.
- Which atom gives electrons in sodium chloride, and which takes them?
- Why does salt not conduct when it is solid but does when dissolved?
- Why does magnesium oxide melt at a much higher temperature than sodium chloride?
After the chapter, the learner can
- Draw dot and cross diagrams for ions such as sodium chloride
- Explain why ionic compounds have high melting points and conduct when molten
What they copy into their notebook
A metal atom loses electrons and a non-metal atom gains them, so both ions have full outer shells. Oppositely charged ions attract in a giant lattice: high melting point, and it conducts only when molten or dissolved.