Unit 5Unit 5Naming Ionic CompoundsThe MoleHydrocarbonsPercent CompositionEmpirical and Molecular Formulas

Unit 5 Naming and Writing Unit 5 Naming and Writing Formulas for Ionic and Formulas for Ionic and Covalent Compounds. 6.4, Covalent Compounds. 6.4, 6.5, 6.66.5, 6.6Quick Review

◦How can you tell whether a compound is ionic or covalent (molecular)? Ionic compounds are composed of a

_________ and a _________________.

◦A positively charged ion is a ________. Ex: K+ - which means potassium ______ an

electron A negatively charged ion is an _________. Ex: Cl- which means chlorine _______ an

electron.

Unit 5 Naming compoundsUnit 5 Naming compoundsExamples:

◦Li + S

◦Mg + N

◦Fe(III) + O

Unit 5 Naming Ionic Unit 5 Naming Ionic CompoundsCompoundsA chemical compounds name should

indicate its _____________, ___________, and how it is ________ to other compounds.

Compounds composed of two elements are called ___________ compounds.

Compounds that contain atoms of three different elements are ___________ compounds (usually contain a polyatomic ion.

Unit 5 Naming Ionic Unit 5 Naming Ionic CompoundsCompoundsThe cation is always named first and

the anion will be named second.The cation takes the name from the

element. Ex: Na+ Sodium Ex: K+ Potassium

The anion is named by taking the root of the elements name and adding “ide”◦Ex: Cl- Chloride◦Ex: S2- Sulfide

Unit 5 Naming Ionic Unit 5 Naming Ionic CompoundsCompoundsExamples

◦Na + Br

◦Ca + Br

◦Ga + Cl

Unit 5 Naming Ionic Unit 5 Naming Ionic CompoundsCompoundsHow to name binary compounds

with multiple charges.◦_____________ metals all have elements

with multiple charges.◦The cation (transition metal) is named

first and the anion is named second◦The cation takes on the name of the

element and the charge is placed in ___________. Ex: Cu+ is Copper (I) ALL transition metals must show the charge

in parenthesis except Zn2+, Cd2+, Ag+

Unit 5 Naming Ionic Unit 5 Naming Ionic CompoundsCompoundsExamples:

◦CuCl2 Copper(II) Chloride

◦CuCl Copper(I) Chloride

◦Fe2O3

Iron (III) Oxide

Unit 5 Naming Ionic Unit 5 Naming Ionic CompoundsCompoundsHow to name ternary ionic

compounds.◦First name the cation and then the

polyatomic ion.◦The polyatomic ions usually end in

“_____” or “________”.◦The two polyatomic ions that end in

“ide” are ___________ and __________.◦Ex: Ca(NO3)2

◦K2SO4

◦Mg(OH)2

◦Fe(SO4)

Unit 5 Naming Ionic Unit 5 Naming Ionic CompoundsCompoundsPolyatomic Ions

◦YOU MUST MEMORIZE THE FOLLOWING POLYATOMIC IONS.

◦Acetate (C2H3O2-)

◦Hydroxide (OH-)◦Sulfate (SO4

2-)

◦Sulfite (SO32-)

◦Nitrate (NO3-)

◦Nitrite (NO2-)

◦Carbonate (CO32-)

◦Ammonium (NH4+)

Unit 5 Naming Covalent Unit 5 Naming Covalent Molecular CompoundsMolecular CompoundsCovalent compounds share

electrons so there are not charges. Instead we use prefixes.Mono 1

Di 2

Tri 3

Tetra 4

Penta 5

Hexa 6

Hepta 7

Octa 8

Nano 9

Deca 10

Unit 5 Naming Molecular Unit 5 Naming Molecular CompoundsCompoundsExamples: Give the formula for

the following molecular compounds.

N2O

Cl2O8

SO3

Unit 5 Naming Unit 5 Naming CompoundsCompoundsMixed examples:Be(NO3)2

N2H4

PI3

ZnO

Unit 5 Naming Unit 5 Naming CompoundsCompoundsGive the formula of the following

molecular compounds from their names.◦Nitrogen trifluoride

◦Disulfur dichloride

◦Dinitrogen tetroxide

Unit 5 Naming Unit 5 Naming CompoundsCompoundsWrite the formulas for the

following substances.Magnesium sulfide

Calcium carbonate

Dichlorine heptoxide

Carbon tetrachloride

Unit 5Unit 5Percent CompositionPercent CompositionTaking a look at Percents…..

◦What is the percent of boys in the class?

◦What is the percent of girls in the class?

◦How did you solve for this?

Percent CompositionPercent CompositionTells a chemist how much of each

element or polyatomic ion is present in a compound on a percent basis.

It is the mass of an element or polyatomic ion that is present in 100 g of a compound.

The percent composition has as many percent values as there are different elements in the compound

Percent CompositionPercent CompositionCompound FormulaCompound FormulaThe formula of a compound shows

which atoms it contains and how many atoms of each it contains.◦Ex: Na2S

There are 2 sodium atoms and 1 sulfur atom

Must know how to find molar mass of a compound from its chemical formula◦Ex: Find the molar mass of the compound

CuSO4

Percent CompositionPercent CompositionSolving for Percent Composition

◦% of an element = mass of element mass of compound

◦Ex: CuSO4

Percent CompositionPercent CompositionPractice

◦Calculate the percent composition of propane (C3H8)

◦Calculate the percent composition of ethane (C2H6)

◦Calculate the percent composition of sodium bisulfate (NaHSO4)

Percent Composition of Percent Composition of HydratesHydratesWhen ionic compounds are

crystallized from an ionic solution they take up a definite proportion of water as a part of their structure.

The compound that contains water is known as the hydrate and the water is known as the water of hydration.◦% water = mass of water X 100 mass of the hydrate

Percent composition of Percent composition of HydratesHydratesExample

◦CuSO4*5H2O

◦MgSO4 *7H2O

Unit 5 The Mole 7.1 and Unit 5 The Mole 7.1 and 7.27.2What is the mole and why do we

use it?

Atoms are extremely small which means a sample of matter contains too many atoms to count. The mole allows us to count the atoms.

Unit 5 The MoleUnit 5 The MoleMole Conversions

◦The mole is used in a number of conversions between mass, particles, and volume.

◦1 mole = 6.02 x 1023 particles (atoms, molecules or formula units).

◦1 mole = 22.4 L◦1 mole = the molar mass of a

substance

Unit 5Unit 5 The MoleThe MoleExample:

◦Co is a metal that is added to steel to improve its resistance to corrosion. Calculate both the number of moles in a sample of Co containing 5.00 X 1020 atoms and the mass of the sample.

Unit 5Unit 5 The MoleThe MoleExample: Jugalone, a dye known for

centuries is produced from the husks of black walnuts. It is also a natural herbicide that kills off competitive plants around the black walnut tree but does not affect grass and other noncompetitive plants. The formula for jugalone is C10H6O3. A sample of 1.56 x 10-2 g of pure jugalone was extracted from the husks. How many moles of jugalone does this sample represent?

Unit 5Unit 5 The MoleThe MoleExample: Calcium carbonate is

the principle mineral found in limestone, marble, chalk, pearls, and the shells of marine animals like clams. A certain sample of calcium carbonate contains 4.86 moles. What is the mass in grams of this sample?

What is the mass of carbonate ions present?

Unit 5Unit 5 The MoleThe MoleExample: Determine the volume

in L of 0.60 mol sulfur dioxide gas at STP.

Unit 5 Unit 5 The MoleThe MoleExample: How many moles is

0.880 L He?

Unit 5Unit 5Empirical/Molecular Formulas Empirical/Molecular Formulas 7.37.3Empirical Formulas

◦Gives the lowest whole number ratio of the atoms of the elements in a compound

◦Ex: Hydrogen Peroxide normally reported as H2O2 (Molecular formula).

◦The empirical formula would be HO

Unit 5 Empirical FormulaUnit 5 Empirical FormulaDetermine the empirical formula

for a compound that gives the following percentages upon analysis (in mass%).

71.65% Cl24.27% C4.07% H

Unit 5 Empirical FormulaUnit 5 Empirical FormulaStep 1 - ALWAYS assume you

have 100 g of the substance. Then convert the percentages to grams.◦71.65 g Cl, 24.27 g C and 4.07 g H

Step 2 – Convert the masses of each element to moles by dividing by the molar mass.

Unit 5 Empirical FormulaUnit 5 Empirical FormulaStep 3 – Choose the smallest

amount of moles and divide each mole amount by that number to get the ratio of atoms in the compound.

Divide each one by the lowest amount.

Unit 5 Molecular FormulaUnit 5 Molecular FormulaThe exact formula of a

substance. This is the formula you normally see in your book.

Ex: The molecular formula for hydrogen peroxide is H2O2.

You must know the molar mass of the molecular formula and the empirical formula to find the molecular formula.

Unit 5 Molecular FormulaUnit 5 Molecular FormulaCalculate the molecular formula for

the previous example. Remember the empirical formula was CClH2. The molar mass is 98.96g/mol.

Step 1 – Find the Empirical FormulaStep 2 – Divide the molar mass by

the empirical formula mass (If you forget the larger mass will always go on top and that will always be the molar mass.

Unit 5 Molecular FormulaUnit 5 Molecular FormulaStep 3 – multiply the number

from the second step by the subscripts in the empirical formula. This will give the molecular formula.

The empirical formula was CClH2Multiply all by 2 and the

molecular formula is C2Cl2H4

Unit 5 Molecular FormulaUnit 5 Molecular FormulaA white powder is analyzed and

found to contain 43.64%P and 56.36%O by mass. The compound has a molar mass of 283.88 g/mol. What are the compound’s empirical and molecular formulas?

Unit 5 Molecular FormulaUnit 5 Molecular FormulaCaffeine, a stimulant found in

coffee, tea, and chocolate, has an empirical formula of C4H5N2O, and has a molar mass of 194.2g/mol. Determine the molecular formula of caffeine.

HydrocarbonsHydrocarbonsSections 25.125.225.3

What are hydrocarbons?What are hydrocarbons?Just like the name says…..

They are compounds composed only of Carbon and Hydrogen!

HydrocarbonsHydrocarbonsAlkanesAlkanesContain only single covalent

bondsAlso referred to as saturated

hydrocarbons.

HydrocarbonsHydrocarbonsDraw complete structural

formulas for the straight chain alkanes that have three and four carbons.

HydrocarbonsHydrocarbonsHow many single bonds are How many single bonds are in a propane molecule?in a propane molecule?

Alkenes and AlkynesAlkenes and AlkynesAlkenes: double bond hydrocarbons

Alkynes: triple bond hydrocarbons

These are also referred to as unsaturated compounds.

Still follow the same chart as alkanes, but end in ene or yne instead of ane.

Alkenes and AlkynesAlkenes and AlkynesExamplesExamples1 – Ethene:

1 – Ethyne:

Draw the structure formula Draw the structure formula for 2-pentynefor 2-pentynePent is 5yne means triple bond

Draw the structural formula Draw the structural formula for 2-Butenefor 2-ButeneBu means 4ene means double bond

Structural IsomersStructural IsomersCompounds that have the same

molecular formula but different molecular structures

Ex: Butane

Structural IsomersStructural Isomers2-methylpropane

Structural IsomersStructural IsomersC5H10

IsomersIsomers

Draw a structural isomer Draw a structural isomer Hexane

Name the following Name the following IsomersIsomers

Name the following Name the following IsomersIsomers