1. Chapter 4
Ionic Compounds

2. Atoms and Their Ions
In 1916, Gilbert N. Lewis pointed out that the lack of chemical reactivity of the noble gases indicates a high degree of stability of their electron configurations

3. The Octet Rule
Octet rule: the tendency of group 1A-7A elements to react in ways that achieve an outer shell of eight valence electrons
gain electrons = a negatively charged ion called an anion
lose electrons = a positively charged ion called a cation
Link to exercise

4. The Octet Rule
Example: in losing one electron, a sodium atom forms a sodium ion, which has the same electron configuration as neon
Na (11 electrons): 1s2 2s2 2p6 3s1
Na+ (10 electrons): 1s2 2s2 2p6

5. The Octet Rule
Example: in gaining one electron, a chlorine atom forms a chloride ion, which has the same electron configuration as argon
chlorine atom (17 electrons): 1s2 2s2 2p6 3s2 3p5
chloride ion (18 electrons): 1s2 2s2 2p6 3s2 3p6

6. The Octet Rule The octet rule is good; but you have to think also
Real life ideas
Metals are + so Bi doesn’t become -3
Nonmetals – so B doesn’t become +3

7. Naming Cations
Elements of Groups 1A, 2A, and Al form only one type of cation; the name of the cation is the name of the metal followed by the word “ion” “Always ions”

8. Naming Cations For cations derived from other metals,
use Roman numerals to show charge
Example:
Iron(II) is Fe2+
Iron (III) is Fe3+

9. Naming Cations
Do Not Use

10. Naming Anions
For monatomic (containing only one atom) anions, add “ide” to the end
here are the monatomic anions we deal with most often

11. Polyatomic Ions
common names, where still widely used, are given in parentheses

12. Forming Chemical Bonds
According to the Lewis model
an atom may lose or gain enough electrons to acquire a filled valence shell and become an ion. An ionic bond is the result of the force of attraction between a cation and an anion.
an atom may share electrons with one or more other atoms to acquire a filled valence shell. A covalent bond is the result of the force of attraction between two atoms that share one or more pairs of electrons.

13. Forming an Ionic Bond In forming sodium chloride, NaCl
we use a single-headed curved arrow to show this transfer of one electron

14. Reactions Sodium reacts with chlorine
ION electronic configuration exercise

15. Formulas of Ionic Compounds
The total number of positive charges must equal the total number of negative charges
lithium ion and bromide ion form LiBr
barium ion and iodide ion form BaI2
aluminum ion and sulfide ion form Al2S3
sodium ion and bicarbonate ion form NaHCO3
potassium ion and phosphate ion form K3PO4

16. Naming Ionic Compounds
Binary ionic compounds
the name of metal from which the positive ion is formed followed by the name of the negative ion; subscripts are ignored
AlCl3 is aluminum chloride
LiBr is lithium bromide
Ag2S is silver sulfide
MgO is magnesium oxide
KCl is potassium chloride

17. Naming Ionic Compounds
Binary ionic compounds of metals that form two different cations
for systematic names, use Roman numerals to show charge on the metal ion; for common names (not used in this class), use the -ous, -ic suffixes
CuO is copper(II) oxide; cupric oxide
Cu2O is copper(I) oxide; cuprous oxide
FeO is iron(II) oxide; ferrous oxide
Fe2O3 is iron(III) oxide; ferric oxide

18. Naming Ionic Compounds
Ionic compounds that contain polyatomic ions
name the positive ion first followed by the name of the negative ion
NaNO3 is sodium nitrate
CaCO3 is calcium carbonate
NaH2PO4 is sodium dihydrogen phosphate
NH4OH is ammonium hydroxide
FeCO3 is iron(II) carbonate; ferrous carbonate
Fe2(CO3)3 is iron(III) carbonate; ferric carbonate
CuSO4 is copper(II) sulfate; cupric sulfate

19. Forming a Covalent Bond
A covalent bond is formed by sharing one or more pairs of electrons
the pair of electrons is shared by both atoms and, at the same time, fills the valence shell of each atom
example: in forming H2, each hydrogen contributes one electron to the single bond

20. Molecular Compounds
Molecular compound: a compound in which all bonds are covalent
Naming binary molecular compounds
the less electronegative element is named first
prefixes “di-”, tri-”, etc. are used to show the number of atoms of each element; the prefix “mono-” is omitted when it refers to the first atom, and is rarely used with the second atom. Exception: carbon monoxide
NO is nitrogen oxide (nitric oxide)
SF2 is sulfur difluoride
N2O is dinitrogen oxide (laughing gas)

21. Lewis Structures
You will build models and draw Lewis Structures in Lab.
You will have to identify the polarity in a molecules as well.
Link to polarity idea