1. When Elements Combine
Most elements do not occur in nature in pure form – instead they occur in compounds – combinations of two or more elements in fixed proportions
We say that the individual atoms of the different elements are held together in these compounds by “chemical bonds”
Fundamentally, the nature of chemical bonding is driven by the octet rule – the tendency of atoms to give, take, or share electrons so the outermost energy level (s and p orbitals) is filled.

2. Types of Chemical Bonding
There are three types of chemical bonds
ionic bonds connect metals to nonmetals
covalent bonds connect nonmetals to nonmetals
metallic bonds connect metals to metals
What kind of bond connects
nitrogen (N) and oxygen (O)?
copper (Cu) and tin (Sn)?
iron (Fe) and chlorine (Cl)?
carbon (C) and fluorine (F)?
sodium (Na) and iodine (I)?
aluminum (Al) and sulfur (S)?

3. Ionic Bonding
Ionic bonds come from the electrical attraction between positively charged metal ions (cations) and negatively charged nonmetal ions (anions)
The Periodic Table shows us that metals generally have three or fewer valence electrons – and the octet rule then tells us that these elements tend to lose electrons and become cations.
The Periodic Table also shows us that nonmetals generally have four or more valence electrons – and the octet rule then tells us that these elements tend to gain electrons and become anions.

4. Naming Ionic Compounds
Thus, when a metal combines with a nonmetal, the metal gives up electrons, the nonmetal takes electrons, and the resulting cation and anion are attracted to each other
Compounds held together by ionic bonds are called “ionic compounds”
Ionic compounds are given names as follows:
the name of the cation then the name of the anion
cation names = element names
anion names = element “root” + “ide”

5. Naming Ionic Compounds
There are two special conditions to keep in mind:
Transition metals can have multiple valence states
To show which valence state is present, a roman numeral is placed after the element name
iron (II) has a +2 charge; iron (III) has a +3 charge
Polyatomic ions are groups of covalently bonded nonmetals that behave as a single ion
polyatomic ions have their own names (which are listed in the reference table)
with the exception of ammonium (NH4+), the polyatomic ions are negatively charged

6. Naming Ionic Compounds
Let’s try some!!
Fe (+3) and O
Ca and F
Pb and S
K and OH
Zn and CO3
Cu (+1) and C2H3O2
NH4 and Cl
iron (III) oxide
calcium fluoride
lead sulfide
potassium hydroxide
zinc carbonate
copper (I) acetate
ammonium chloride

7. Formulas for Ionic Compounds
We use the element symbols of the cation and anion to write “formulas” for ionic compounds
Ionic compounds must be electrically neutral
Thus the “fixed proportion” of elements in an ionic compound is the number of cations and anions required to balance the total positive and negative charges
We write the number of cations/anions required as a subscript to the right of the element symbol
Barium chloride = Ba+2 and Cl-1 = BaCl2
Potassium oxide = K+1 and O = K2O

8. Formulas for Ionic Compounds
Let’s try some!!
iron (III) oxide
calcium chloride
hydrogen sulfate
aluminum fluoride
copper (I) sulfide
barium phosphate
ammonium hydroxide
Fe2O3
CaCl2
H2SO4
AlF3
Cu2S
Ba3(PO4)2
NH4OH