I. Using Symbols to Write Formulas: (2-1, 2-2)

AP Chemistry Name ______Period ___ Date ___/___/___ 2  Nomenclature of Acids N O T E S

Note: IF you have ANY trouble with this sections – this is the place to go!: http://www.chemteam.info/ChemTeamIndex.html (choose Nomenclature), in the book, sections 4-5, 6 (note: the weblinks have practice problems with answers!!!)

A. Chemical formulas:

1. Formulas describe the ratio of atoms/ions in a substance or the number of atoms/ions in a single molecule of the substance

2. Subscripts tell you the number of each atom/ion in the formula (note: no subscript is used for 1)

. ex: NaCl, CH3COOH, CH4

B. Types of formulas:

1. Elements: (see 2-1)

a. monatomic, ex: ______

b. diatomic, ex (list 7): ______

c. polyatomic, ex: (list 2) ______

2. Compounds: can be expressed as

a. simplest whole number ratio of atoms (ionic) CaCl2

b. actual number of atoms in a molecule (covalent) CH3COOH

II. Types of Compounds

A. Identify components of compounds - Use the “staircase” on the periodic table (see Table 4-2, p 126)

1. left and below the “staircase”: metals? nonmetals? metalloids?

2. right and above the “staircase”: metals? nonmetals? metalloids?

3. along the “staircase”: metals? nonmetals? metalloids?

0150e7f4c4e6fab1dc47ee3263a0214a.doc 1 Marsden, Christine B. Step 1 in naming/writing formulas: Identify types of compounds

1. “Ionic” - Metal + Nonmetal (or polyatomic ion)

a. (note: always expressed as simplest ratio of ions - called “formula units”)

b. ex. NaCl, MgCl2, Al2(SO4)3 (why are these ionic?)

2. “Molecular” or “Covalent” - do not start with a metal!

a. formula expressed as actual number of each type of atom in the formula

b. ex. C6H6 (not CH), SiO2, CS2

3. Which are ionic? Which are covalent? (see bottom of page for answers)1

a. b. c. SO2 CaCl2 N2O4

III. Covalent compounds (don’t forget – start with a nonmetal!)

A. Naming Covalent (Molecular) Compounds: Formula to Name (p. 51, 142) Note we will only use the “traditional” method), http://www.chemteam.info/Nomenclature/Binary-Greek-FormulatoName.html

1. Some have common names (those below you need to know)

H2O: ______CH4 ______

NH3: ______CH3OH______

CH3COOH______

1 1) covalent, 2) ionic, 3) covalent, 4) ionic p. 2 2. Naming binary (containing two types of atoms) molecular compounds

remember: these compounds are identified by LACKING metals

3. Steps for naming: a. Name the elements in the same order they appear in the formula b. Drop the last syllable (or two!) of the second element and add “-ide” (see table 4-11)

element symbol element name as second element, name becomes (same as for ionic)

Cl chlorine

Br bromine

O oxygen

S sulfur

N nitrogen nitride

P phosphorus phosphide

c. Add prefixes to the name of each element to indicate the number of atoms of that element in the molecules  Prefixes: (see p. 142)

1 mono 4 6 9

2 5 7 10

Note: for the first element, mono is not used (no prefix needed) 4. Examples See write at least 3 examples here:

p. 3 B. Writing Formulas for Covalent (Molecular) Compounds: Name to Formula (p. 51, 142) (http://www.chemteam.info/Nomenclature/Binary-Greek- NametoFormula.html )

1. Use the prefixes to determine the number of each atom

2. Examples: see link (above) write at least 3 here

Note: for covalent compounds, DO NOT reduce subscripts!!! Subscripts reflect the ACTUAL NUMBER of each type of atom in the molecule

Special note: With regard to acids: Acids are covalent compounds, but have special rules which we shall touch on later in the notes.

p. 4 IV. Ionic Compounds (Compounds with Metal + Nonmetal, or with polyatomic ion) *** Be sure to print out the list of polyatomic ions to know!!! ***

A. Writing formulas – ionic compounds (links:

 http://www.chemteam.info/Nomenclature/Binary-Fixed- NametoFormula.html

 http://www.chemteam.info/Nomenclature/Binary-Stock- NametoFormula.html

 http://www.chemteam.info/Nomenclature/Binary-Comm- NametoFormula.html

 http://www.chemteam.info/Nomenclature/Polyatomic- NametoFormula.html

1. First, we need to know about ions and their charges -

a. Metals – lose electrons to become + ions (cations)

 Ca  Ca2+ Ca+2  Na  Na1+ or Na+ or Na+1

b. Ions formed from elements in groups 1 & 2 have +1 and +2 charges, respectively

 Ba  Cs Note: Hydrogen can combine as a +1 with a nonmetal

c. Ions you need to remember (table 2-3): Ag Zn Al

d. If the metals are other transition metals, you need to be given a “hint” – called “Stock System”

 Parentheses and Roman numerals used to indicate charge

(i) Copper (I)  Cu1+ (ii) Copper (II)  Cu2+

 Also, common names are used (and should be memorized!)

Element Lower Oxidation State Higher Oxidation State Stock Name Common Name Stock Name Common Name +1,+2 Copper copper (I) cuprous copper (II) cupric +1, +2 Mercury* mercury (I) mercurous mercury (II) mercuric +2,+3 Iron iron (II) ferrous iron (III) ferric +2,+4 Tin tin (II) stannous tin (IV) stannic +2, +4 Lead lead (II) plumbous lead (IV) plumbic p. 5 2+ *Note: mercury (I) is actually a polyatomic ion: Hg2 , ex: mercury (I) fluoride Hg2F2

e. Nonmetals: based on family

 Nonmetals: gain electrons to become – ions (anions)

 Halogens (group 17): Cl  Cl1-

 Oxygen group (group 16):O  O2-

 Nitrogen group (group 15) N  N3-

Note: Hydrogen can combine as a –1 with a metal: ex NaH called sodium hydride

f. PAI – need to memorize!!!

2. To write formulas, combine the two charged particles in the lowest whole number ratio to give a net charge of 0.

 Now, let’s write formulas (first, go to web link from above)

 Don’t forget – we need to BALANCE the charge with the lowest whole number

lithium bromide iron(III) chloride

magnesium oxide copper(II) sulfide

calcium nitride tin(IV) iodide

aluminum sulfide aluminum hydroxide

mercurous chloride calcium acetate

stannic fluoride potassium permanganate

B. Naming – ionic compounds (see

 http://www.chemteam.info/Nomenclature/Binary-Fixed- FormulatoName.html

 http://www.chemteam.info/Nomenclature/Binary-Stock- FormulatoName.html p. 6  http://www.chemteam.info/Nomenclature/Binary-Comm- FormulatoName.html

 http://www.chemteam.info/Nomenclature/Polyatomic- FormulatoName.html

1. Cation

a. Metal: If only one possible charge, then just name it

b. If transition metal (and not silver or zinc), need to

 determine charge (Figure out what charge it would need in order to balance the charge in the formula)

(i) FeCl3 (ii) Mn2O7

 name using Stock system or common name (Stock is preferable)

c. + If polyatomic ion (usually NH4 ), just name it

2. Anion

a. Nonmetal – change the ending to –ide

b. Polyatomic ion – just name it

3. Examples:

a. Ca3N2 b. AuCl