1. Chemical Names & Formulas
Chapter 9

2. Ionic vs. Covalent
Ionic bonds form between a metal cation and a non-metal anion.
There is a full transfer of electrons.
A covalent (molecular) bond occurs between two non-metals.
Electrons are shared.

3. IONS Ion – an atom or group of atoms with a charge
Cation – Ion with a positive charge
Anion – Ion with a negative charge
Monatomic ion – consist of a single atom
Polyatomic ion – consists of more than one type of atom

4. CATIONS Elements in group 1, 2, and 3 lose electrons and form cations.
Why is sodium + 1 and magnesium is + 2?
(hint: drawing a diagram may help)
Atoms try to achieve noble gas configuration with their electrons.
Cations have the same name as the element from which they form

5. ANIONS Elements in group 15, 16, & 17 gain electrons to form anions
How many electrons will chlorine gain?
what will its charge be?
Monatomic anions have the ending -ide
The remaining elements in group 4 & don’t normally form ions. Why?

6. Ions of Transition Metals
Transition metal cations may have more than one possible charge.
Iron for example can have a +2 or a +3 oxidation state.
A roman numeral in parantheses shows the oxidation state of the metal.
e.g. Iron (III), Iron (II)

7. …continued
A few transition metals have only one oxidation state (Ag+, Cd2+, Zn2+) and do not need a Roman Numeral.
Can you find any other transition metals that have only one oxidation state?

8. Writing Formulas Formulas need to have an overall charge of zero.
Write the symbol of the cation first then the anion. Then, add whatever subscripts are needed to balance the charges.
Example:
Potassium chloride is composed of
K+ and Cl -
The formula is KCl

9. …CONTINUED The formula for lithium oxide is Li2O
Each lithium has one positive charge, so two lithium atoms are needed to balance the –2 charge on oxygen.
The formula for aluminum oxide is Al2O3
How do we come up with this formula?

10. The Crisscross Method
If the charges do not already add to zero, the numerical value of the charge can be crossed down to become the subscript of the other ion.
Al O2-

11. Polyatomic Atoms
Composed of more than one atom, most of these ions end in –ite or -ate

12. Formulas With Polyatomics
Write the symbols for the cation followed by the formula for the polyatomic anion, and balance the charges.
If you need more than one polyatomic ion, (parentheses are necessary)
Calcium nitrate is written Ca(NO3) 2

13. PRACTICE Write the correct formula for the following: Lithium fluoride
Magnesium chloride
Aluminum sulfide
Calcium phosphate
Potassium chlorite

14. Things to keep in mind…
There are three common polyatomic ions that end in –ide
Hydroxide
Peroxide
Cyanide
You may run into 3 names together, e.g. sodium hydrogen carbonate.

15. Naming Molecular Compounds
Molecular compounds are covalently bonded and are composed of two non-metals.
What are the names for CO2 and CO?
Carbon dioxide & carbon monoxide.
Where do we find each of these gases?

16. PREFIXES
Prefixes tell us how many atoms of an element are present in each molecule of a compound. 1 2 3 4 5 6 7 8 9 10
Mono Di
Tri
Tetra
Penta
Hexa
Hepta
Octa
Nona
Deca
Omit the prefix mono- when the formula contains only one atom of the first element in the name.
The ending of the second element is –ide
The vowel at the end of a prefix is dropped if the name of the elements begins with a vowel.

17. Writing Formulas for Molecular Compounds
The prefix tells you the subscript of each element in the formula.
Silicon carbide has no prefixes and has the formula SiC.
Dinitrogen tetroxide is N204

18. ACID
An acid contains one or more hydrogen atoms and produces H+ ions when dissolved in water.
Formic Acid Hydrofluoric Acid

19. Naming Acids
Formulas are generally in the form HnX, where X is an anion.
The name system depends on the name of the anion, suffix.

20. RULES
When the anion ends in –ide, the acid name begins with hydro – and ends in – ic (followed by the word acid) ex. HCl = hydrochloric acid
When the anion ends in –ite, the acid name ends in – ous (followed by the word acid) ex. H2S03 = sulfurous acid.
3) When the anion ends in –ate, the acid name ends in – ic (followed by the word acid) ex. HN03 = nitric acid.

21. Naming Bases Bases are named the same way as other ionic compounds.
Ex. NaOH = sodium hydroxide
Al(OH)3 = aluminum hydroxide