1. Unit 4

2. Naming and Writing Chemical Formulas
Nomenclature
Naming and Writing Chemical Formulas

3. Formulas and Nomenclature
Chemical formulas show the number of atoms in a compound.
“Nomenclature” is a naming system.
The “nomenclature” system for people is first and last names.
The typical “nomenclature” system for marriages is that the man keeps his last name and the bride changes her last name.

4. 2 main types of compounds
Ionic compounds A positive ion and a negative ion. OR YOU COULD SAY... A metal and a nonmetal. A metal and a polyatomic ion.

5. 2 main types of compounds
Covalent compounds Made of more than one nonmetal atom.

6. 2 main types of compounds
Acids
Made up of positive hydrogen ions paired with negative ions.
These compounds appear to be covalent (all nonmetal) but act like ionic compounds.

7. Ionic nomenclature
An ion is written as the element symbol with a superscript to the right showing the charge.
Na1+
O2-
Fe3+
The sign (+/-) tells us whether electrons have been gained or lost.
The number tells us how many electrons have been gained or lost.

8. Ions
Find Monatomic Ions here! Monoatomic ions consist of a single atom with a + or – charge because of the loss or gain of an electron.

9. What is the charge of the following ions?Li Be Al Na F Cl I Ca Si S Fr C Ra Mg H K O N P Sr B

10. If you are given a formula of ionic compound and need to name it…
First, make sure it is ionic by looking for a metal. Example: K2Se
If the metal has only one possible charge (like group 1, group 2, Al and a few transition metals, then just name the metal and the other ion. Nonmetal ion names end in –ide. Example: Potassium selenide
CaCl2
Monatomic cation = name of the element
Ca2+ = calcium
Monatomic anion= root + -ide
Cl- = chloride
calcium chloride

11. Practice
1. CaS
2. MgBr2
3. CsClO3

12. Naming Ionic Compounds
1. Make sure the compound is ionic by looking for a metal.
Calcium chloride
2. Write the ion symbols with their charges.
Ca+2 Cl-1
3. Cross the charges over and take the absolute value. These numbers become the subscripts. Reduce the subscripts if they are divisible by an integer.
CaCl2

13. Practice
Sodium sulfide
Barium oxide
Zinc nitride
Magnesium chloride

14. What is a Polyatomic Ion?
An ion made of 2 or more atoms
These atoms can be of the same element
O22-
These atoms may be of different elements
HCO3-
BO33-
The charge following a polyatomic ion is the total charge on all the atoms of the ion, not just the charge on the last atom. (ACT AS A SINGLE UNIT)

15. How to work with polyatomic ions…
If a polyatomic needs a subscript, put a parenthesis around the polyatomic ion to show that more than one polyatomic is present.
Ex: Magnesium hydroxide
Mg2+OH1-
Mg(OH)2
Iron (II) hydroxide
Cobalt (II) phosphate
Tin (IV) sulfate

16. If the metal has more than one possible charge…
You will need to reverse cross the subscripts to determine the charge of the metal. You must include the roman numeral as part of the metal ion name.
FeCl3 (Fe3+) iron (III) chloride
CuCl2 (Cu+ ) copper (II) chloride
1. PbCl4
2. Cr(NO3)3
3. NiPO4

17. Common Transition Metals
Elements that can have more than one possible charge
MUST have a Roman Numeral to indicate the charge on
the individual ion.
-ous means lower charge
-ic means higher charge

18. Complete the names of the following binary compounds with variable metal ions:
1. FeBr2
CuCl
SnO2
4. Fe2O3

19. Write the formula from the name (remember – the Roman numeral gives you charge of the cation)
5. Chromium (III) iodide 6. Tin (IV) oxide 7. Mercury (I) sulfide 8. Copper (II) fluoride

20. Write the formula for the following ternary compounds:
9. Strontium phosphate 10. Lithium acetate 11. Platinum (I) nitrite 12. Chromium (IV) sulfate

21. Name the following: 23. Na2O 24. CaCO3 25. PbS2 26. Sn3N2 27. Cu3PO4 28. HgF2
Write the formula:
29. Copper (II) chlorate
30. Calcium nitride
31. Aluminum carbonate
32. Potassium bromide
33. Barium fluoride
34. Cesium hydroxide

22. Covalent Formulas
Fill in the blanks to complete the following names of covalent compounds using the prefixes.
CO carbon ______oxide
CO2 carbon _______________
PCl3 phosphorus _______chloride
CCl4 carbon ________chloride
N2O _____nitrogen _____oxide
Mono 1* Di 2
Tri 3
Tetra 4
Penta 5
Hexa 6
Hepta 7
Octa 8
Nona 9
Deca 10
*mono is omitted if on the first element

23. Naming Covalent Compounds
If you are given the name of a covalent compound and need to name it:
First, make sure the compound is covalent by noting that it is made up of 2 nonmetals. Examples: Dinitrogen Monoxide
Next, use the latin prefixes to translate the chemical name. The prefixes refer to the elements they are attached to.
Example: Dinitrogen means “two nitrogens”
Monoxide means “one oxygen”
N2O

24. Practice **Do not reduce subscripts for covalent compounds
Dinitrogen tetroxide
Sulfur trioxide
Tetraphosphorus decasulfide
**Do not reduce subscripts for covalent compounds

25. If you are given the formula of a covalent compound and need to write the formula, use the prefixes to indicate the number of atoms of each element. “Mono” is never used with first element and second element will have –ide ending.
4. NF3
5. PCl5
N2O3
C2F4

26. Mixed Practice BaI2 Dinitrogen monoxide P4S3 Potassium sulfide Ca(OH)2
Copper (II) nitrate
Dichlorine heptoxide
Chromium (III) sulfate
Iron (III) sulfite
Calcium oxide
Barium carbonate
Iodine monochloride
BaI2
P4S3
Ca(OH)2
FeCO3
Na2Cr2O7
I2O5
Cu(ClO4)2
CS2
B2Cl4

27. Acid Nomenclature Acids
They are an important class of hydrogen-containing compounds that are named in a special way. They will be written with H as the first element.
Examples:
HCl (aq) – hydrochloric acid
HNO3 – nitric acid
H2SO4 – sulfuric acid O H N O O
Use IUPAC rules for naming ionic compounds when naming bases.

28. Naming acids

29. HCN
HNO2
H2SO3
Permanganic acid
Dichromic acid