Unit 6

Chemical Naming and MolesChapter 9-10

Naming Ions

Positive Ions, cations, simply retain their name. Na+ Sodium Ion Mg2+ Magnesium Ion

Naming Ions

Negative Ions, anions, change ending of element to –ide Cl- Chloride Ion Br- Bromide Ion

Unique Anions Names N3- Nitride Ion

O2- Oxide Ion

S2- Sulfide Ion

P3- Phosphide Ion

Polyatomic Ions

Selected polyatomic ions are on Table E in the Reference Tables.

Polyatomic ions keep their names in most chemical names

Naming Systems

Ionic System Stock System (Roman Numerals) Binary Covalent System (Prefixes)

When to use ionic system

First element is a metal NaCl

More than 2 elements, meaning polyatomic ion is involved NH4Cl

Naming Ionic Compounds

Name positive ion first, then negative ion. NaCl Sodium chloride Mg(OH)2 Magnesium hydroxide

Problem Name these 2 compounds, using the

ionic system

CuCl Copper Chloride

CuCl2 Copper Chloride

Different compounds need to have different names

Stock System

Use when the metal element has more than one positive oxidation number

Stock System

We must indicate which charge the metal ion has, using Roman Numerals CuCl CuCl2 Cu+1 Cu+2

Copper(I)ChlorideCopper(II)Chloride

Roman Numeral is the charge of the metal ion

Roman NumeralsCation Charge

Roman Numeral

+1 I

+2 II

+3 III

+4 IV

+5 V

+6 VI

+7 VII

+8 VIII

Example

Fe3(PO4)2

Iron(II) Phosphate

-3

-3

+6 -6

PO4

PO4

Fe

Fe

Fe+2

+2

+2

Binary Covalent Compounds

Use when compound is 2 nonmetals Including metalloids

Use a prefix system to indicate the number of atoms for each element

Second element ends in -ide

Prefixes

Number of atoms Prefix

1 mono-

2 di-

3 tri-

4 tetra-

5 penta-

6 hexa-

7 hepta-

8 octa-

Example

N2Cl3 Dinitrogen Trichloride

Exceptions

When there is only one atom of the first element, do not use mono- prefix. CO2

Carbon dioxide OF2

Oxygen difluoride

Exceptions

When an element starts with a vowel, drop any o or a at the end of a prefix CO

Carbon Monooxide Carbon Monoxide

P2O5

Diphosphorus Pentaoxide Diphosphorus Pentoxide

Words representing Numbers

Dozen 12 Baker’s Dozen 13 Gross 144 Ream 500 Mole 6.02 x 1023

Avogadro’s Number

6.02 x 1023

Number of representative particles in a mole

1 mol He = 6.02 x 1023 atoms 1 mol H2 = 6.02 x 1023 molecules

Practice

2 mol H2 = 12.04 x 1023 molecules

2 mol H2 = 24.08 x 1023 atoms

2 mol H2O = 36.12 x 1023 atoms

2 mol C6H12O6 = 72.24 x 1023 O atoms

Mole-Mass relationship

1 mole of any element equals the atomic mass in grams

1 mol Carbon = 12.01g Carbon

1 mol Iron = 55.8g Iron

Gram Formula Mass

Mass of the formula in g/mol Simply add the atomic masses of

each element in the formula together

H2O = 1 + 1 + 16 = 18 g/mol Also known as gram atomic mass,

gram molecular mass, molar mass

Rounding

Round most masses to the nearest whole gram

Except: Copper, Cu 63.5 Chlorine, Cl 35.5

Practice

KNO3 = 39 + 14 + 16(3) = 101 g/mol

C6H14 = 12(6) + 1(14) = 86 g/mol

CuSO4 = 63.5 + 32 + 16(4) = 159.5 g/mol

Mole - Mass Conversion

Example: 96 g of Oxygen gas = ? mol

molmolg

gmol 3

/32

96#

Practice

How many moles are there in 506g of ethanol, C2H6O?

What is the mass of 8 moles of CCl4?

molg

gx

/46

506

molg

xmol

/1548 1232g CCl4

11 mol C2H6O

Molar Volume

At STP, 1 mol of any gas occupies 22.4L of space

Examples: 2 mol of He occupies how much

space at STP? 11.2L will have how much H2 gas

at STP?

44.8L

0.5 mol

Mole Road Map

Review

How many moles are in 584g of SF6?

How many grams are in 6 mol of HCl?

X =584g

146 g/mol= 4 mol

6 mol =X

36.5 g/mol= 219 g

Percent Composition

%100*Whole

Part

Example

H2O

H

100*18

2

11.1% H

O

100*18

16

88.9% O

Another Example

NH3

N

100*17

14

82.4% N

H

100*17

3

17.6% H

Percent Composition

What is the percent composition of oxygen in H2SO3?

58.5% 100*82

48

Percent Composition

What is the percent composition of aluminum in Al2(SO4)3?

15.8% 100*342

54

Percent Composition

What is the percent composition of nitrogen in NH4NO3?

35% 100*80

28

Hydrates

Compounds that have a specific number of water molecules attached

Dot means plus (+) gfm = 159.5 + 5(18) = 249.5g/mol

CuSO4·5H2O

Formulas

Molecular Formula Shows the total number of atoms in a

molecule H2O

Structural Formula Shows the total number of atoms in a

molecule, and how the bonds are arranged

O H

H

Empirical Formula

Simplest Whole-Number ratio of atoms in a compound

Examples CO2

P4O10 P2O5

C6H12O6 CH2O

Empirical Formula

Molecular Formula is a multiple of the Empirical Formula

Examples

Compound that has 4 carbon atoms for every 8 hydrogen atoms

C4H8 CH2

Compound that has 6 carbon atoms for every 18 hydrogen atoms

C6H18 CH3

Empirical Formula

A molecular formula has an empirical formula of CH2 and a molecular mass of 28 g/mol.

A molecular formula has an empirical formula of CH2 and a molecular mass of 42 g/mol.

C2H4

C3H6