Nomenclature Chapter 4

Common names of chemicals don’t tell us much: Epsom Salts Gypsum Sugar Laughing Gas What are they?

A system of naming compounds which indicates composition is needed. CHAPTER 4 GOAL: By the end of the chapter, be able to name a compound when given its formula, and produce the formula when given the compound name.

Oxidation Number A representation of how many electrons have been gained or lost by the element For each electron the element loses the oxidation number increases by one

Example: Cu(II) has two more protons than electrons, giving it a charge of +2. So if the element were Cu(IV) that would mean that the copper element had lost 4 electrons and had a charge of +4

Binary Compounds: Compounds composed of two elements Two Classes of Binary Compounds: 1.Compounds containing a metal and a nonmetal 2.Compounds containing two nonmetals

Binary Ionic Compounds Contain a cation and an anion Cation is always written first in the formula There Are Two Types of Binary Ionic Compounds

Type I Binary Compounds: The metal present forms only one type of cation Naming Type I Ionic Compounds 1.The cation is always named first and anion second 2.A simple cation (obtained from a single atom) takes its name from the name of the element 3.A simple anion (obtained from a single atom) is named by taking the root of the element name and adding -ide

Example: Na + = sodium ion Cl - = chloride ion NaCl = sodium chloride Do: Self Check 4.1 pg 88

Type II Binary Compounds: The metal present can form two (or more) cations that have different charges Naming Type II Binary Compounds Use the oxidation number of the anion (nonmetal) to determine which charge of cation (metal) is present Write the charge of the cation with Roman Numerals

Example: CoBr 2 Co = cobalt (II) (2+) Br 2 = bromine -1(2 atoms) = (2-) cobalt (II) bromide

CoCl 3 cobalt (III) chloride CuI copper (I) iodide SnBr 4 tin (IV) bromide PbS lead (II) sulfide Do: Self Check Exercise 4.2 pg 93

Type III Binary Compounds Only contain nonmetals Naming Type III Binary Compounds 1.The first element in the formula is named first, and the full element name is used 2.The second element is named as if it were an anion 3.Prefixes are used to denote the numbers of atoms present 4.The prefix mono is never used for naming the first element

Example: BF 3 B = boron F 3 = trifluoride

CF 4 carbon tetrafluoride PCl 3 phosporus trichloride I2O7I2O7 diiodine heptoxide Do: Self Check 4.3 pg 95

IN SUMMARY STEP 1 Look at the cation Determine if it is a Type I, II, or III STEP 2 Name accordingly –Type I cation / anion (-ide) –Type II cation (roman numeral) / anion (-ide) –Type III (prefix) cation / (prefix) anion (-ide)

I IIIII

Polyatomic Ions Charged entities composed of several atoms bound together You MUST memorize the polyatomic ion names in table 4.4 pg 100 Do: Self Check 4.4 pg 97 Focus Question #5 pg 100 Self Check 4.6 pg 102

QUIZ 1.Al 2 S 3 2.AgCl 3.FeI 3 4.HgO 5.SeO 6.P 2 S 5 7.MnF 2 8.PCl 3 9.Cr(C 2 H 3 O 2 ) 2 10.Fe(NO 3 ) 3 1.aluminum sulfide 2.silver chloride 3.iron (III) iodide 4.mercury (II) oxide 5.selenium monoxide 6.diphosphorus pentasulfide 7.manganese (II) fluoride 8.phosphorus trichloride 9.chromiuim (II) acetate 10. iron (III) nitrate

Oxyanions Series (set number) of polyatomic ions which contain an atom of a given element and different numbers of oxygen atoms Names: Hypo- less than Per- more than -ite smaller -ate larger

Example: ClO - hypochlorite ClO 2 - chlorite ClO 3 - chlorate ClO 4 - perchlorate

Naming Compounds Containing Polyatomic Ions Example: Na 2 SO 4 Two sodium ions One sulfate ion sodium sulfate

Example: KH 2 PO 4 One potassium ion + Two hydrogen ions 2+ One phosphate ion 3- potassium dihydrogen phosphate Polyatomic

Example: Mn(OH) 2 One manganese ion (2 + ) Two hydroxide ions (2 - ) manganese (II) hydroxide

Writing Formulas from Names Just Work Backwards!!!!! Example: potassium hydroxide K + OH - =KOH sodium carbonate Na + CO 3 2- =Na 2 CO 3 Do: Self Check 4.7 pg 103 and Self Check 4.8 pg 106

Naming Acids Rule 1 If the anion does not contain oxygen: Prefix = hydro- Suffix = -ic Example: HCl = hydrochloric acid

Rule 2 If the anion does contain oxygen: The name is formed from the root of the central element of the anion name Suffix = -ic or –ous If the anion ends in –ate the suffix –ic is used If the anion ends in –ite the suffix -ous is used Example: H 2 SO 4 = sulfuric acid H 2 SO 3 = sulfurous acid (sulfate) (sulfite)