4.4 More about ions Flashcards
What do hydrogen and the metals form.
Hydrogen and the metals lose electrons and form positive ions. The ions have the same names as the atoms.
What do non-metals form?
Non-metals form negative ions, with names ending in -ide.
Why don’t the elements in Group IV and V form ions?
The elements in Groups IV and V do not usually form ions, because their atoms would have to gain or lose several electrons, and that takes too much energy.
Why don’t the elements in Group VIII form ions?
Their atoms already have stable outer shells, so do not need to gain or lose electrons.
The names of ionic compounds
To name an ionic compound, you just put the names of the ions together, with the positive one first.
Ion in compound K+ and F-
potassium fluoride
Ion in compound Ca2+ and S2-
calcium sulfide
The formulae of ionic compounds
The formulae of ionic compounds can be worked out using these four steps.
Steps to make the formula of an ionic compound
- Write down the name of the ionic compound
- Write down the symbols for its ions
- The compound must have no overall charge, so balance the ions until the positive and negative charges add up to zero.
- Write down the formula without the charges.
Lithium fluoride ionic compound formula
- LIthium fluoride
- The ions are Li+ and F-, to make the total charge zero
- The formula is LiF.
Sodium sulfide ionic compound formula
- Sodium sulfide
- The ions are Na+ and S2-.
- Two Na+ ions are needed for every S2- ion, to make the total charge zero: Na+Na+S2-
- The formula is Na2S
Silver ion
Silver only forms Ag+ ions
Zinc ion
Zinc only forms Zn2+ ions.
Compound ions
Group of bonded atoms.
Ammonium ion
NH4+
