Chemical Nomenclature (Naming Chemical Compounds)

1. Chemical Nomenclature(Naming Chemical Compounds)

2. Three types of compounds require three types of names • Ionic compounds-metals and nonmetals • Molecular compounds-covalently bound nonmetals • Acids-most molecular compounds where hydrogen is the cation

3. Monatomic Ions • Ions formed from a single atom are called monatomic ions • Common monatomic ions on page 221 • many d-block elements can form more than one ion with different charges • Use Roman numerals to show the charge on d-block elements

4. Some Common Monatomic IonsMain-group Elements

5. Some Common Monatomic Ionsd-block Elements

6. Binary Ionic Compounds • The total number of positive charges must equal the negative charges so the compound comes out nuetral • In order to figure out the number of cations and anions use the Least Common Multiple (LCM) • A shortcut for this is the criss-cross method

7. Naming ionic compounds • Name the cation (positive ion) first. If the metal has more than one oxidation number use roman numerals to indicate which. • Then name the anion. If the anion is a single type of atom, its name will most likely end in –ide. • If the anion is a polyatomic, just name the anion. • Learn the names as soon as possible!

8. Example: • Lets look at the ionic compound NaNO3. • The cation is sodium. • The anion is the nitrate ion. • So the name is: sodium nitrate.

9. Naming covalent compounds • Name the least electronegative first. • Then name the most electronegative. • Use prefixes: mono-, di-, tri- etc. to indicate more than one of each. • The name will end in –ide if there are only two elements present.

10. Example: • Name the covalent molecule CO2. • Carbon is less electronegative than oxygen, so it is named first. It is not necessary to say monocarbon. • Since there are two oxygens we say di and since there are two elements, oxide. • The name is carbon dioxide.

11. Naming acids • If the acid is binary (hydrogen and only one other element) then the acid is: • Hydro________ic acid, the other element’s root word goes in the blank. • If the acid is ternary (hydrogen and a polyatomic ion) then change the ending of the ion from –ate to –ic or from –ite to –ous and add the word acid.

12. Two examples of acids: • Name HBr • It is a binary acid, so the name is • Hydrobromic acid • Name HNO3 • It is ternary, and NO3-1 is the nitrate ion, so the –ate becomes ic • Nitric acid

13. Assigning Oxidation Numbers • The oxidation number of an element in its free (uncombined) state is zero. • The sum of all oxidation numbers in a neutral compound is zero. • The oxidation number on a monatomic ion is equal to the charge on the ion • The sum of all oxidation numbers in a polyatomic ion is equal to the charge on the ion.

14. Assigning Oxidation Numbers • Group 1 – oxidation number +1 • Group 2 – oxidation number +2 • Group 13 – oxidation number +3 • Group 14 – oxidation number +4 / -4 • Group 15 – oxidation number -3 • Group 16 – oxidation number -2 • Group 17 – oxidation number -1

15. Assigning Oxidation Numbers – Transition metals • Transition elements can have more than 1 oxidation state. Common examples are: • Cr - chromium (II) or chromium (III) • Mn – manganese (II) or manganese (III) • Fe – iron (II) or iron (III)

16. Assigning Oxidation Numbers – Transition metals (continued) • Co – cobalt (II) or co (III) • Cu - copper (I) or copper (II) • Hg – mercury (I) or mercury (II) • Sn – tin (II) or tin (IV) • Pb – lead (II) or lead (IV)

17. Using Oxidation Numbers to Determine Formulas • Oxidation numbers can frequently be used like ionic charges to determine formulas