SCH3U1
Ions and Ionization
Atoms are neutral since the number of protons (+) in the nucleus
equals the number of electrons (-) in the orbits or energy levels.
The main group elements have a tendency to gain or lose valence (outer
orbit) electrons in order to produce a complete outside orbit. In this
process they form ions or charged atoms.
Elements with a full outer orbit of electrons are said to have a stable
octet. Neutral atoms will tend to gain or lose electrons to produce a
stable octet, where the electron arrangement is the same as that of the
closest noble gas.
* Note that since every element in a family or group has an equal
number of valence electrons, they will tend to gain or lose the same
number of electrons. This explains their similar reactivity.
Metals tend to lose electrons, forming positive ions.
Non-metals tend to gain electrons, forming negative ions.
Ionization equations show the formation of ions by loss or gain of
electrons.
a fluoride ion is formed
eg) fluorine gains 1 electron
F + 1e-
F-
a neutral F gains 1 electron
an aluminum ion and 3 electrons form
eg) aluminum loses 3
electrons
Al
-
a neutral Al atom
Al3+
+
3e
Write the ionization equations for the following elements:
a) Be
b) K
c) P
d) Ne
e) O
IONIC BONDING
A chemical bond is a force of attraction between two atoms or
molecules.
IONIC BONDS are bonds that occur due to the electrostatic attraction
between positive and negative ions. Since metals (on the left side of
the periodic table) lose electrons to non-metals (on the right side), they
form compounds due to the attraction between their resulting ions.
Sodium (with 1 valence electron) loses 1 electron to chlorine (with 7
valence electrons). This can be represented as the sum of 2 ionization
equations:
Na
Na+
Cl + 1e-
+
Cl-
1e-
The sum of these two equations represents the formation of the
compound NaCl:
Na
+
Cl
NaCl
If the number of electrons lost or gained is not equal, the number of
atoms in the compound will not be equal.
Mg
2Cl + 2eMg + 2Cl
Mg2+
+ 2e2ClMgCl2
The subscript in a chemical formula indicates the number of each type
of ion in the compound. These subscripts are commonly determined
using the “criss-cross rule”.
This type of simple compounds is called a binary compounds because
they contain only 2 types of elements.
NOMENCLATURE OF BINARY COMPOUNDS
Simple Binary Compounds:
Chemical nomenclature refers to the system used by chemists to name compounds.
The naming system for simple binary ionic compounds is quite simple. The ion
with the positive charge (metal) is written first, followed by the negative ion (nonmetal) with the suffix –ide.
For example:
NaCl
sodium chloride
magnesium chloride
MgCl2
AlF3
aluminum fluoride
beryllium oxide
BeO
Li3N
____________________
calcium phosphide
______
BaF2
____________________
strontium bromide
______
* Note that BeO has no subscripts since each ion has a charge of -2.
Compounds Containing Variable Valence Elements:
Some elements like iron, copper, lead and tin are multivalent, meaning they have
more than 1 common charge. To name these compounds, the IUPAC method
assigns a Roman numeral to indicate the charge:
FeCl2
iron (II) chloride
lead (IV) nitride
Pb3N4
CuO
_______________
tin (II) carbide
______
AuBr3
_______________
cobalt (II) iodide
______
SCH3U
Naming Simple Binary Compounds
PART A: Name the following compounds.
e.g. NaF = sodium fluoride
1. NaCl _________________________
3. CaO _________________________
2. CaCl2 _____________________________
5. CaS _________________________
6. Ag2S ______________________________
7. H2O _________________________
8. AlI3 _______________________________
9. Na2O ________________________
10. Al4C3 ____________________________
11. Mg3N2 ______________________
12. H2S ______________________________
13. AlN _________________________
14. SiC ______________________________
4. MgBr2 ____________________________
PART B: Write the chemical formula for the following compounds.
e.g. beryllium nitride = Be3N2
1. aluminum carbide ____________
2. hydrogen oxide _____________________
3. aluminum oxide ______________
4. hydrogen sulfide ______________________
5. silicon carbide ________________
6. calcium chloride ____________________
7. sodium chloride _______________
8. sodium oxide _______________________
9. magnesium bromide ___________
10. calcium sulfide ____________________
11. hydrogen sulfide _____________
12. magnesium nitride ________________
13. aluminum oxide _____________
14. calcium oxide _____________________
PART C: Write the name or formula of these compounds containing metal ions with
variable valences (charges).
1. copper (II) fluoride _____________ 2. Pb3P2 _______________________________
3. tin (IV) oxide __________________
4. Cu2S ________________________________
5. iron (III) oxide _________________ 6. MnF4 _______________________________
7. gold (III) chloride ______________
8. HgS _________________________________
9. iron (III) carbide _______________
10. SnO2 ________________________________