Topic 6: Chemical Compounds Continued
Remember there are two types of chemical
compounds molecular/covalent and ionic.
When an atom gains or loses electrons it is not
neutral it possesses a charge and becomes an ion.
When an atom loses an electron it becomes
positively charged.
When an atom gains an electron it becomes
negatively charged.
Examples: How many electrons have the sodium,
calcium, chlorine and boron ions lost or gained?
Example: How many protons and electrons do each of
the ions in the previous example have?
When ions bond they create ionic compounds.
Ionic Compounds
• a metal, (positive) with a non – metal, (negative)
• contain ions in solution
• can conduct electricity
• solids at room temperature
Naming Ionic Compounds
1. Write the name of the metal ion first.
2. Write the name of the non – metal second changing
the end to “ide”.
NEVER USE PREFIXES FOR IONIC COMPOUNDS
Example: Write the name for the following ionic
compounds.
CaCl2
ZnS
NaCl
Sc2O3
NaF
Na2S
LiCl
Writing the Chemical Formula for Ionic Compounds
1. Write the symbol of the metal first. Give it the charge
of the non – metal as a sub – script.
2. Write the symbol of the non – metal second. Give it
the charge of the metal as a subscript.
3. Reduce the charges if possible.
***Always “swap” charges***
Example: Write the formula for the following ionic
compounds.
lithium chloride
zinc chloride
strontium nitride
calcium oxide
Polyatomic ions
• A polyatomic ion is a charged species that has two or
more atoms bonded together.
• When you name ionic compounds with polyatomic ions
use the same procedure but DO NOT change the name
of the polyatomic ions.
Example: Name the following:
(NH4)2O
(NH4)2(Cr2O7)
Be(Cl4)2
Polyatomic ions Continued
• When you find the chemical formula for polyatomic
ionic compounds use the same procedure but make sure
to put the polyatomic ion(s) in brackets.
Example: Find the formulas for:
ammonium phosphide
lithium carbonate
magnesium sulfate
ammonium phosphate