Today is Friday (!),March 13th, 2015

Pre-Class:Can you name these compounds?

H2O

CO2

NaClHCl

Today you will need your periodic tables that show the charges for transition metals. You also need a small paper towel for

you and your partner.

Stuff You Need:Periodic TablePaper Towel

In This Lesson:Unit 3Ionic

Nomenclature and Polyatomic

Ions(Lesson 1 of 4)

Pre-Class Deux

• Can you name these compounds?– O2

• Oxygen gas

– O3

• Ozone gas

– CO• Carbon monoxide

– H2SO4

• Sulfuric Acid

Today’s Agenda

• Namin’ stuff.– In today’s case, ionic compounds and polyatomic

ions.

• Where is this in my book?– P. 254 and following…

By the end of this lesson…

• You should be able to name ionic compounds, including those with polyatomic ions.

Quick Reminders

• A compound is a chemical combination of two or more elements (like the pre-class ones).

• Subscripts indicate how many atoms of an element are present.– H2O = 2 Hydrogen, 1 Oxygen

– CO2 = 1 Carbon, 2 Oxygen

• Note that subscripts only apply to the letter next to them (unless there are parentheses).

Quick Reminders

• Chemists don’t write ones.– Na+ has a charge of 1+.– Cl- has a charge of 1-.– K2S has one sulfur atom.

Quick Reminders

Nd2-

Charge (1-)

Subscript (2 Nd atoms)

Quick Reminders

• For elements whose symbols have two letters (or even three), only the first letter is capitalized.– For example, Cobalt is abbreviated Co.– If you write CO, another person might think it’s a

compound of Carbon (C) and Oxygen (O).• That’s carbon monoxide!• Both are deadly, but don’t confuse them.

Quick Reminders

• Remember that cations are positively-charged ions, and anions are negatively-charged.– Most cations are metals; some polyatomic ions.• Example: Ca2+, NH4

+

– Most anions are nonmetals; many polyatomic ions.• Example: Cl-, SO4

2-

Cations and Anions

• And since cations and anions attract one another…

• They form ionic bonds, making ionic compounds.

Need to Know Information

• Now, to name any compound or derive its formula, you need to know:– What kind of elements are involved?• Metal, nonmetal, or metalloid.

– How many elements are there?• 2 – binary compound• 3 – ternary compound (usually has a polyatomic ion)

– Are there polyatomic ions?

Wait…polyatomic?

• Polyatomic ions are (usually) small compounds that behave as one ion.– In other words, there’s more than one element, but

they act as one. Poly-atomic…get it?• You should memorize as many of these as

possible.– Yes, really.

• Here’s a hint:– Anything ending in “-ide,” except Hydroxide, Peroxide,

and Cyanide, will be found on the periodic table.– Everything else is on the polyatomic ion charts.

Polyatomic Ion List• I will give you a list of polyatomic ions, but I assure you

that studying/memorizing the list will be extremely helpful.– Note: You will not have a polyatomic ion list on the final.

• Also helpful will be the following slide that shows how many of the names for polyatomic ions are determined.

• Important Note:– “Hydrogen carbonate” is the same as “Bicarbonate.”– “Hydrogen sulfite” is the same as “Bisulfite.”– “Hydrogen sulfate” is the same as “Bisulfate.”– Acetate is more commonly written as C2H3O2

-

– Chloride (Cl-) is NOT a polyatomic ion. Just cross it out.

Most Common Polyatomic IonsThese are worth memorizin’!

• Acetate (C2H3O2-)

• Carbonate (CO32-)

• Chlorate (ClO3-)

• Hydroxide (OH-)• Nitrate (NO3

-)

• Phosphate (PO43-)

• Sulfate (SO42-)

• Ammonium (NH4+)

Naming Polyatomic Ions

• There’s a system to how these polyatomic ions are named.

• It’s not the most helpful, but getting a little familiar with this might be useful.

• Let’s take a look…

Naming Polyatomic Ions

Main IonClO3

-

Chlorate

CO32-

Carbonate

PO43-

Phosphate

NO3-

Nitrate

SO42-

Sulfate

BrO3-

Bromate

Naming Polyatomic Ions with Chlorine

Anion Name Number ofOxygen Atoms

Cl- Chloride 0 – “-ide”

ClO- Hypochlorite 1 – “hypo…ite”(2 fewer than main)

ClO2- Chlorite 2 – “ite”

(1 fewer than main)

ClO3- Chlorate 3 – “ate”

(main ion)

ClO4- Perchlorate 4 – “per…ate”

(1 more than main)

Naming Polyatomic Ions

No O -2 O -1 O Main Ion +1 OCl-

ChlorideClO-

HypochloriteClO2

-

ChloriteClO3 –

ChlorateClO4

-

Perchlorate

STAR WARS!(not real)

CO32-

Carbonate

P3-

PhosphidePO3

3-

PhosphitePO4

3-

Phosphate

N3-

NitrideN2O2

2-

HyponitriteNO2

-

NitriteNO3

-

Nitrate

S2-

SulfideSO3

2-

SulfiteSO4

2-

Sulfate

Br-

BromideBrO-

HypobromiteBrO2

-

BromiteBrO3

-

BromateBrO4

-

Perbromate

Time for some practice!

• Polyatomic Ion Puzzle– The puzzle is like dominoes - match the names of

polyatomic ions to their formulas.• Note that some sides may not be used.• Some ions are represented more than once.• Try many possibilities – don’t give up!

– HINTS:• There are four obvious corner pieces.• Cyanide, chromate, dichromate, hydrogen carbonate,

and permanganate only have one match each.• It’s a 4x4 grid.

Now that that’s over…

• Let’s make sure we know how to predict ionic charges a little more specifically.

Group 1: Lose 1 electron to form 1+ ionsH+

Li+

Na+

K+

Group 1

Be2+

Mg2+

Ca2+

Sr2+

Ba2+

Group 2

Group 2: Lose 2 electrons to form 2+ ions

Group 13:

B3+Al3+Ga3+

Group 13

Group 13: Lose 3 electrons to form 3+ ions

Group 14:Group 14

Group 14: Rarely form ions

Group 14:Group 14

Group 14: 4+ or 2+ ions

Pb2+Sn4+Ge4+

N3-

P3-

As3-

NitridePhosphideArsenide

Group 15

Group 15: Gain 3 electrons to form 3- ions

Group 16:

O2-

S2-

Se2-

OxideSulfideSelenide

Group 16

Group 16: Gain 2 electrons to form 2- ions

Group 17:

F-

Cl-

Br-

FluorideChloride

BromideI- Iodide

Group 17

Group 17: Gain 1 electron to form 1- ions

Group 18:Group 18

Group 18: Noble gases do not form ions

Hey, wait a sec…

• By now you may be thinking, “But Mr. G…didn’t you forget the transition metals?”

• No. I did not. Chill.– They’re just weird.

Groups 3 - 12:

Fe2+ = Iron (II)Fe3+ = Iron (III)

Transition Metals

Transition Metals: Many transition metals have more than one oxidation state

Multivalent Elements• For transition elements (and some others), things

can get tricky.• Most have either 1 or 2 valence electrons.• Some have more or less.• Some have more than one amount of valence

electrons.– These are called multivalent metals because they

have multiple valence numbers (charges).• They are often written as this:– Element (charge written as Roman numeral)

Common Multivalent Elements• Copper (Cu) – either 1 or 2 valence electrons.– Copper (I) or Copper (II) – 1+ or 2+

• Nickel (Ni) – either 2 or 3 valence electrons.– Nickel (II) or Nickel (III) – 2+ or 3+

• Iron (Fe) – either 2 or 3 valence electrons.– Iron (II) or Iron (III) – 2+ or 3+

• Lead (Pb) – either 2 or 4 valence electrons.– Lead (II) or Lead (IV) – 2+ or 4+

• Tin (Sn) – either 2 or 4 valence electrons.– Tin (II) or Tin (IV) – 2+ or 4+

• Mercury (Hg) – either 1 or 2 valence electrons.– Mercury (I) or Mercury (II) – 1+ or 2+

However…

• Some transition elements have only one possible oxidation state.– Zinc (Zn) – Zn2+

– Silver (Ag) – Ag+

Valence Electrons andMultivalent Metals

• How many valence electrons does Iron (I) have?– One.• If it forms a +1 charge, it must have one electron to give

up.

• How many valence electrons does Lead (IV) have?– Four.• If it forms a +4 charge, it must have four electrons to

give up.

Nomenclature

• Before we begin nomenclature, I’m going to hand out a flowchart to everyone.

• Treat this piece of paper like it’s a piece of solid Au, or Pt.– Get it?

• Anyway, this paper will save you a lot of frustration. Trust me.

Nomenclature• We now reach something called nomenclature,

which is a fancy name for a very particular naming system.– Ain’t that a coincidence?

Nomenclature

• When naming ionic compounds (that’s today’s lesson), cations’ names are not changed.– In other words, a sodium ion is called a “sodium ion.”

• Anions, however, are referred to by the element stem followed by –ide.– Chlorine becomes chloride, nitrogen becomes nitride,

fluorine becomes fluoride (becomes toothpaste).• Thus, NaCl is called “sodium chloride,” not “sodium

chlorine” or “sodide chloride” or whatever.

Procedure

• To name ionic compounds, follow these four steps:1. Write the symbols for the cation and anion, including

charges. Put polyatomic ions in a circle. Do not change anything in the circle.

2. Check to see if the charges are balanced (=0).3. Balance charges, if necessary, using subscripts.4. If you need more than one of a polyatomic ion, use

parentheses at the end. ONLY for polyatomics!• Simplify subscripts, remove circles and charges to clean it all

up.

Remember the Goal

• Your goal is to make sure that the positive parts of the compound are completely balanced with the negative ones.– In other words, the overall charge adds to 0.

Quick Reminder

Nd2-

Charge (1-)

Subscript (2 Nd atoms)

Example: Iron (III) chloride

1. Write the symbols for the cation and anion, including charges.

2. Check to see if the charges are balanced (=0).3. Balance charges, if necessary, using subscripts.– Clean it up (and don’t leave a space).

Fe3+Cl-3

Not balanced!Total Positive

Charge3+

Total Negative Charge

1-

Total Negative Charge

3-

Example: Barium nitrate

1. Write the symbols for the cation and anion, including charges. Put polyatomic ions in a circle.

2. Check to see if the charges are balanced (=0).3. Balance charges, if necessary, using subscripts.4. If you need more than one of a polyatomic ion, use

parentheses. ONLY for polyatomics!– Clean it up.Ba2+ ( )2NO3

-

Not balanced!Total Positive

Charge2+

Total Negative Charge

1-

Total Negative Charge

2-

About Parentheses

• Parentheses make a difference only when you have multiple polyatomic ions.

• Imagine if you need multiple pairs of shoes. You want two sets of shoes, not just two left shoes.

• Similarly, (OH)2 says you want two sets of OH.

• However, OH2 says you want water and wrote it backward.• Parentheses don’t make a difference if it’s just an atom or

one polyatomic ion.– You write Cl2, not (Cl)2.

– (NO3)3 or (OH)2 are not the same as N3O9 and OH2.

Total Positive Charge

1+

( )

Example: Ammonium sulfate1. Write the symbols for the cation and anion, including

charges. Put polyatomic ions in a circle.2. Check to see if the charges are balanced (=0).3. Balance charges, if necessary, using subscripts.4. If you need more than one of a polyatomic ion, use

parentheses. ONLY for polyatomics!– Clean it up.

NH4+ SO4

2-2

Not balanced!Total Negative

Charge2-

Total Positive Charge

2+

Total Positive Charge

3+

Total Negative Charge

2-

Total Positive Charge

6+

Example: Aluminum sulfide

1. Write the symbols for the cation and anion, including charges.

2. Check to see if the charges are balanced (=0).3. Balance charges, if necessary, using

subscripts.– Clean it up. Al3+ S2-

2 3

Not balanced!Total Negative

Charge6-

Alternative Method: The Cross-Over

Al3+ S2-2 3

Example: Magnesium carbonate

1. Write the symbols for the cation and anion, including charges. Put polyatomic ions in a circle.

2. Check to see if the charges are balanced (=0).– Clean it up. Remember to simplify.

Mg2+

Are balanced!

CO32-

Total Negative Charge

2-

Total Positive Charge

2+

Example: Zinc hydroxide1. Write the symbols for the cation and anion, including

charges. Put polyatomic ions in a circle.2. Check to see if the charges are balanced (=0).3. Balance charges, if necessary, using subscripts.4. If you need more than one of a polyatomic ion, use

parentheses. ONLY for polyatomics!– Clean it up.

Zn2+ ( )2OH-

Not balanced!Total Negative

Charge1-

Total Positive Charge

2+

Total Negative Charge

2-

Example: Aluminum phosphate

1. Write the symbols for the cation and anion, including charges. Put polyatomic ions in a circle.

2. Check to see if the charges are balanced (=0).– Clean it up.

Al3+

Are balanced!

PO43-

Total Positive Charge

3+

Total Negative Charge

3-

Practice

• To practice all this stuff, let’s turn to the Nomenclature Practice Sheet worksheet, first page.

• Try the first section (1-12).

Now let’s do all that again. Backwards.

• You’ve now learned how to write the formula of an ionic compound from its name.

• Now let’s take the formula of an ionic compound and write its name.

Binary Compounds

• Binary compounds are those with two elements.– Example: CaCl2

• For these, first write the cation:– Calcium

• Then write the anion root (chlor–) with the suffix –ide.– chloride

• Calcium chloride!

Binary Compounds

• What’s the name of NaCl?– Sodium chloride

• Al2O3

– Aluminum oxide• AlN– Aluminum nitride

Binary Compounds

• What’s the name of MgI2?– Magnesium iodide

• AlCl3

– Aluminum chloride

• Na3P– Sodium phosphide

Binary Compounds

• Remember there are some elements that are multivalent.

• For these, you need to specify which charge that particular ion is carrying (in parentheses).– Do this by figuring out the negative charge and

working backward to find the cation charge.• Example on the next slide…

Binary Compoundswith Multivalent Elements

• What is the name of PbCl2?• Well, we know it’s Lead (___) chloride, but we

need to figure out the kind of lead we have.– Lead could be 4+, 2+, or possibly something else.

• To figure that out, let’s start with Chlorine.– Two chlorines each show up to this party, each with a 1-

charge. Total charge? 2-.• With one Lead atom balancing this out, the Lead

must be Lead (II).– Lead (II) chloride!

Binary Compoundswith Multivalent Elements

• What’s the name of PbO2?– Lead (IV) oxide

• Mn2O3

– Manganese (III) oxide

• CuCl2

– Copper (II) chloride

• Ti(Cr2O7)2

– Titanium (IV) dichromate

PbO2

-4+4

Mn2O3

-6+6

CuCl2

-2+2

Ti(Cr2O7)2

-4+4

Ternary Compounds

• Some compounds, like that last one, contain more than two elements.

• Ternary compounds contain three.– They often include polyatomic ions.

• Naming works the same way.• The trick is to know when you’re looking at a

polyatomic ion.– How do you know? There will be a total of more

than two elements there!

Ternary Compounds

• NaNO3

– Sodium nitrate

• Fe2(SO4)3

– Iron (III) sulfate• Cesium perchlorate– CsClO4

• Ammonium phosphate– (NH4)3PO4

• Calcium hydroxide– Ca(OH)2

Practice

• To practice all this stuff, let’s turn to the Nomenclature Practice Sheet worksheet, first page.

• Try the second section (13-24).

Takeaways

• Roman numerals tell you the charge of an atom, NOT how many there are.– Subscripts tell you how many atoms there are.

• Roman numerals are used only for cations that make multiple charges.– Also, they are only used in names, not formulas.

• Parentheses are used only when you need more than one of a polyatomic ion.– Never around a single element.

It’s time to play…

• Fix That Ionic Compound!• I’ll give you a name and a formula.• Your job is to fix the part that is in bold text.

Fix That Ionic Compound!

• Potassium sulfide is K2S1

– K2S

• BaI2 is barium iodine– Barium iodide

• SrBr2 is strontium (II) bromide– Strontium bromide

• Titanium (IV) oxide is Ti(IV)O2

– TiO2

Corrections

Fix That Ionic Compound!

• CuCl2 is copper chloride– Copper (II) chloride

• The lead in PbO2 has a charge of 2+– 4+

• Magnesium oxide is Mg2O2

– MgO

• Sodium nitrate is Na3N– NaNO3

Corrections

Fix That Ionic Compound!

• There are 4 phosphate molecules in AlPO4

– 1

• Ca(CN)2 is calcium carbon nitride– Calcium cyanide

• Strontium hydroxide is SrOH2

– Sr(OH)2

• Ammonium chlorite is NH4(ClO2)– NH4ClO2

Corrections

Closure

• Remind me what the name of this ion is: Cl-

– Chloride• And do you know what HCl is?– Hydrochloric Acid

• Remind me what polyatomic ion this is: SO42-

– Sulfate

• And do you know what H2SO4 is?– Sulfuric acid

• Any pattern here?

Closure Part Deux

• What’s the name of this compound? CO2

– Carbon dioxide• And what’s the name of this compound? CO– Hint: It’s toxic but odorless and colorless.– Double Hint: You probably own a detector for it.– Triple Hint: It’s not smoke.– Carbon monoxide.

• What’s up with that? Why isn’t it “carbon oxide?”– Hint: Location on the table?– Double Hint: Metal or nonmetal?

Extra Practice

• For extra practice, turn your Nomenclature Practice Sheet worksheets face down and try #1-20.