Chemistry SM-1131Week 6 Lesson 2

Dr. Jesse ReichAssistant Professor of Chemistry

Massachusetts Maritime AcademyFall 2008

Class Today• Molecules, Compounds, Nomenclature• No Class on Friday, but you’ll have to make one up

later, enjoy the weekend• New Material: Polyatomic anions, Molecular

Compounds, Acid Names, Formula Mass

What does that mean?

• Don’t do homework with friends in your room.• Don’t hang with friends when you have to do

work.• Don’t think about work when you are chilling

with friends.• If you got less than a raw 70 you really have to

do the homework or risk failing this course• You won’t pass this class just listening

Compounds

• Joseph Proust- 1754-1826• Law of Constant Composition: All samples of a

given compound have the same proportions of their constituent elements

• Every molecule of water has H2O, every molecule of sugar is C6H12O6

What’s it mean

.

H is the symbol O is the symbol

2 is how many Hs there are

How many Os?

More complicated…

• Mg(NO3)2

• There is one Mg• There are 2 groups of (NO3)

• In each NO3 there is 1 N and 3 O

• The math 2 * 1N = 2N • The math 2 * 3O = 6O• Total formula= Mg1N2O6

Atomic Elements

• Noble Gases, many metals exist simply as just their element

Molecular Elements

• Many elements are not stable enough to exist on their own without forming molecules:

• H = H2, N = N2, O = O2, F = F2, S = S8, Cl = Cl2,

• Br = Br2, I = I2

• These are so unstable they need to form molecules to exist, they are molecular elements

2 Compound Types

• Ionic Compounds: Are between two or more ions, most of them are between a metal and a non-metal

• Molecular Compounds: Are between 2 or more non-metals

Compound TypesIonic: Metal and a non-metalMolecular: 2 non metals

Memorize this Table

• Group 1= +1• Group2= +2• Group13= +3• Group14= + or – 4• Group 15= -3• Group 16 = -2• Group 17= -1• Group 18 = No Charge Ever!

Ionic Compounds

• They are overall neutral, but each component has a charge. So, we have to make sure that charges are balanced.

Ionic Compound Making

• 1- Write their symbols• 2- Write their charges to the upper right• 3-Switcheroo• 4- (Reduce)• MEMORIZE THIS!

Naming Ionic Compounds

• Hold UP!• Ionic Compounds have 1 naming system• Molecular compounds have a 2nd naming

system that works differently• Ionic Compounds are between metals and

non-metals

Naming Metals

• Alkali, alkaline earth, and group 3 metals are easy to name in compounds when saying their names out loud. Just use what you see on the periodic table.

• Al is aluminum, Na is sodium, Mg is Magnesium

Transition Metals

• Alkali metals are easy. The charge is always 1. Alkaline earth metals are easy the charge is always 2. Group 13 metals are easy the charge is always +3.

• Transition metals, lanthanides, actinides, and all the other metals are trickier. There are multiple charges they can have and multiple names for the metals depending on their charge.

T.M. Example

• Iron can exist in stable forms with a +2 or +3 charge. We write the symbol as as Fe+2 and Fe+3 or Fe(II) and Fe(III) or Iron (II) and Iron (III)

• Copper typically has a +1 or +2 charge. We will write it as Cu+1 or Cu+2e or Cu(I) and Cu (II) or Copper (I) and Copper (II)

Transition Metals

• Chemistry is old. We’ve actually gone through 2 naming systems for transition metals.

• The old system had certain names for certain charges. Fe+2 and Fe+3 were called ferrous and ferric. We won’t use those names in here, but you should at least read the list and be familiar.

Naming Ionic Compounds

• The non-metal in ionic compounds gets it’s name changed.

• Chlorine becomes chloride• Oxygen becomes oxide• Nitrogen becomes nitride• Fluorine becomes Fluoride• Sulfur becomes Sulfide• Iodine becomes Iodide

All the way through

• Magnesium and Nitrogen form a compound what is it’s formula and name?

• MgN• Mg+2N-3

• Mg3N2

• Can’t reduce• Magnesium Nitride

What about Iron (II) and Nitrogen

• Fe and N• Fe+2 and N-3

• Fe3N2

• 3:2 doesn’t reduce• Iron (II) Nitride

New Material

• Polyatomic Ions• Ionic Compounds are between metals and

non-metals, AND metals and polyatomic atoms

• Poly=Many• Atomic= Atoms• Polyatomic= many atoms

Polyatomic Anions

• Compounds still work basically the same way• 1- Symbols (keep the parenthesis)• 2- Charges• 3- Switcheroo• 4- Reduce

Example

• Sodium and Carbonate combine to make a compound. What’s the formula and charge?

• Na & (CO3)

• Na+1 and CO3-2

• Na2(CO3)

• Metal First polyatomic ion second• Sodium Carbonate

Example 2

• Magnesium and Phosphate come together to form a compound. Formula and charge?

• Mg & (PO4)

• Mg+2 & (PO4)-3

• Mg3(PO4)2

• Metal first polyatomic ion second• Magnesium Phosphate

Example 2 cont.

• Mg3(PO4)2• There are 3 Magnesium atoms• There are 2 PO4 groups• Each PO4 group has 1 P and 4 O• So, we have to multiply:• 2x 1P = 2P• 2x 4O = 8O• Total: Mg3P2O8

Example 3

• Iron (III) and Nitrate form a compound. What’s the formula and name?

• Fe(III) & (NO3)

• Fe(III)+3 & (NO3)-1

• Fe(III)1(NO3)3

• Iron (III) nitrate• Formula = Fe(III)1N3O9

Example 4• Ammonium and Permanganate form a compound.

Formula and Name?• (NH4) & (MnO4)

• (NH4)+1 & (MnO4)-1

• (NH4)1(MnO4)1

• Ammonium Permanganate• This guy is a rarity because the non-metal thing is the

cation and the metal thing is the anion. Polyatomics can act a little differerntly than metals or non-metals that are just by themselves.

Polyatomics to Memorize

• Table 5.6 page 138• Make note cards. They are all fair game.

Molecular Compounds

• Ionic compounds are between metals and non-metals (or polyatomic ions)

• Molecular compounds are between 2 or more non-metals

Molecular Compounds

• Two different naming systems. DON’T CONFUSE THEM!

• This system is just for molecular compounds.• Molecular compounds have 2 or more non-

metals in them

Molecular Nomenclature

• The naming systems for the simple ones works like this:

• 1-Prefix • 2-First element (somewhat alphabetical)• 3-Prefix• 4-Second element• 5-change the ending of the second element to

-ide.

What are the prefixes

• MEMORIZE THESE!• Mono-1• Di-2• Tri-3• Tetra-4• Penta-5• Hexa-6• Hepta-7• Octa-8

Example

• Here’s a formula: N2O4. What’s the name?• Di• Nitrogen• Tetra• Oxygen• Oxide• Dinitrogen tetraoxide

Example 2

• SF6• Mono (If mono is the very first one you don’t

have to use it).• Sulfur• Hexa• Fluorine• Fluoride• Sulfur Hexafluoride

Example 3

• CO2

• Mono (drop it)• Carbon• Di• Oxygen• Oxide• Carbon Dioxide

Acids

• Acids are things that create H+ ions when dissolved in water. They are typically bitter and sour tasting. Most acids can dissolve metals.

• They are combinations of H+ atoms with anions

Acid Types

• Binary Acids• Oxyacids

Binary Acid Names

• Binary Acids are a combination of 2 things. Hydrogen and one other non-metal

• Naming them is simple• 1-Hydro• 2-Base name of non-metal• 3-change the ending of the non-metal to –ic• 4-Add the word acid at the end

Binary Acid names

• HBr• 1-Hydro• 2-Brom• 3-ic• 4-Acid• Name= Hydrobromic acid

Binary Acid Names

• HCl• 1-Hydro• 2-Chlor• 3-ic• 4- Acid• Name= Hydrochloric Acid

Oxyacid Names

• Oxy Acids are built around compounds that have oxygen containing polyatomic anions in them.

What polyatomic anions make sense?

• Phosphate (PO4)

• Phosphite (PO3)

• Chlorate (ClO3)

• Chlorite (ClO2)

• Nitrate (NO3)

• Sulfate (SO4)

• Sulfite (SO3)

Oxyacid naming with-ate

• 1-Name of the polyatomic acid• 2-change the ending to –ic (sometimes needs

a fudge factor)• 3-add the word acid

Oxyacid Naming• Phosphate makes an acid. What is the name and

formula?• 1-Phosphate• 2-turns into Phosphoric• 3- add acid• Name= Phosphoric Acid• 1-H (PO4)• 2-H+1(PO4)-3• 3-H3(PO4)1

• Can’t reduce

Naming Oxyacids with -ite polyatomic anions

• 1-Write the anion name• 2-Change the ending to –ous (might need a

fudge factor)• 3- add the word acid

Oxyacid Naming with -ite polyatomic anions

• The polyatomic anion sulfite forms an oxyacid. What is the name and formula?

• 1-Sulfite• 2- Change to Sulferous• 3- add Acid• Name= Sulferous Acid• H (SO3)

• H+1 (SO3)-2• H2(SO3)1

• Can’t reduce

Molecular Mass

• To figure out molecular mass you have to know the atomic mass.

• Let’s start easily• Ne- it exists by itself and doesn’t form

molecules. It’s mass is just the atomic mass of Ne, which is 20.18

Simple Molecule Mass

• The mass of N2 is going to be twice the mass of 1 atom of N

• So, if N has an atomic mass of 14.01, then N2 must have a mass of 2x14.01 or 28.02

Molecular Mass

• Ozone has the formula O3, what is it’s molecular mass

• 1 Oxygen has a mass of 16.00• 3x(16.00) has a mass of 48.00 amu

More Complex Masses

• Water has the formula H2O• The molecular mass is going to be from 2H

atoms and 1 O atom, so• 2x(1.0079) + 1x(16.00)= 18.0158amu

Sugar

• C6H12O6• 6(12.01) + 12(1.0079) + 6(16.00)= ???

• Homework due Monday• Work on your Wikis the due date is coming up• Test coming in two weeks