Ionic Bonding
Ions are atoms that have lost or gained one or more electrons, resulting in a positive or negative charge
Cation = a positively charged ion
Anion = a negatively charged ion
Cl
O
*
Are the following ions, cations or anions?
Chlorine ion
Magnesium ion
Oxygen ion
**
*****
gains 1 electron
Cl1- anion
Mg**
loses 2 electrons
Mg2+
cation
**
****
gains 2 electrons
O2-
anion *
*
• Elements in the vertical column families develop the same ionic charges:
Metals tend to lose electrons (form cations).
Non-metals tend to gain electrons (form anions).
Metal cation + Non-metal anion = ionic compound.
Naming Binary Ionic Compounds
• A binary ionic compound is a compound composed of a metal cation and a non-metal anion.
• The first part of the name identifies the positive ion, which is the metal cation.
• The second part of the name identifies the negative ion, which is the non-metal anion.
• The name of the non-metal ion always ends with the suffix –ide.
Elements in Ionic Compound
Name of Ionic Compound
magnesium and phosphorus
sodium and chlorine
calcium and bromine
aluminum and oxygen
magnesium phosphide
sodium chloride
calcium bromide
aluminum oxide
Writing the chemical formulas for binary ionic compounds
1. Write the symbols with the metal first:
aluminum oxide
2. Write the charge above each symbol.3. Cross over the numbers, not the charges.4. Never write a subscript 1.
5. Write the formula, reduce if possible.
• Practice:
Elements in Ionic Compound
Ions Name Chemical Formula
potassium and bromine K1+ and Br1- potassium bromide KBr
magnesium and chlorine Mg2+ and Cl1- magnesium chloride MgCl2
calcium and oxygen Ca2+ and O2- calcium oxide CaO
calcium and iodine Ca2+ and I1- calcium iodide CaI2
aluminum and oxygen Al3+ and O2- aluminum oxide Al2O3
potassium and chlorine K1+ and Cl1- potassium chloride KCl
magnesium and nitrogen Mg2+ and N3- magnesium nitride Mg3N2
sodium and phosphorus Na1+ and P3- sodium phosphide Na3P
aluminum and sulphur Al3+ and S2- aluminum sulphide Al2S3
magnesium and bromine Mg2+ and Br1- magnesium bromide MgBr2
Multivalent Metals
Chemical Formula Name
SnS2
Fe2O3
FeF3
Cr3P2
Multivalent metals have more than one ion charge listed on the periodic table.
For example, copper can form ions with a +1 or +2 charge.
Cu+1 = copper (I)
Cu+2 = copper (Il)
Cu3N =
Practice:
tin (IV) sulphide
iron (III) oxide
iron (III) fluoride
chromium (II) phosphide
[pronounced “copper one”]
[pronounced “copper two”]
copper (I) nitrideCu+1N-3 =
nickel (III) sulphide
osmium (VIII) carbide
Ni2S3
OsC2
Molecular Compounds
Molecular compounds are formed when atoms of two or more different elements SHARE electrons
A covalent bond is formed when electrons are shared between atoms.
for example, water (H20)
Diatomic gases
• H2, O2, Br2, F2, I2, N2, Cl2
oxygen molecule
Elements that have two atoms joined by one or more covalent bonds to form a molecule
The anagram is HOBrFINCl
Element Fluorine Oxygen Hydrogen
Chemical formula of molecule
F2 O2 H2
# of electrons in outer shell
7 6 1
# of electrons to complete outer shell
1 2 1
# of covalent bonds formed
1 2 1
Lewis Diagram of Molecule
What is the difference between a molecular formula and structural formula?
A molecular formula is a chemical formula – it shows the number of atoms of each element.
A structural formula shows the arrangement of the atoms that make up a molecule.
water = H2Oglucose = C6H12O6water = H2Oglucose = C6H12O6water = H2Oglucose = C6H12O6water = H2Oglucose = C6H12O6water = H2Oglucose = C6H12O6
Binary molecular compounds• Binary molecular compounds are compounds composed
of two non-metals joined by one or more covalent bonds.
• You will be using the roman numeral system to name the compounds.
Common examples: carbon dioxide (CO2) carbon monoxide (CO) ammonia (NH3)
Ionic Compounds with Polyatomic Ions
A polyatomic ion is an ion that is composed of more than one type of atom.
A ternary compound is a compound composed of three different elements.
For example: calcium hydroxide
Naming compounds with polyatomic ions follows the same rules as other ionic compounds:
1. Write the cation 1st (e.g. calcium, Ca+2)
each molecule is composed of
Ca(OH)2
1 calcium atom, 2 oxygen atoms, and 2 hydrogen atoms.
2. Write the anion 2nd (e.g. hydroxide, OH-)
Charge Name Chemical Formula
-1
(CN) -
(OH ) -
(NO3 ) -
(ClO3 ) -
(HCO3 ) -
(HSO4 ) -
(H2PO4 ) -
-2
(CO3 ) 2-
(SO4 ) 2-
(HPO4 ) 2-
-3 (PO4 ) 3-
+1 (NH4 ) +
cyanide
hydroxide
nitrate
chlorate
carbonate
sulphate
phosphate
hydrogen carbonate
hydrogen sulphate
hydrogen phosphate
dihydrogen phosphate
ammonium
Name Chemical Formula
calcium carbonate
(NH4)2SO4
Mg3(PO4)2
potassium sulphate
calcium nitrate
Fe(HSO4)3
sodium phosphate
LiOH
cobalt(II) phosphate
Practice:
CaCO3
ammonium sulphate
magnesium phosphate
K2SO4
Ca(NO3)2
iron (III) hydrogen sulphate
Na3PO4
lithium hydroxide
Co3(PO4)2