Chemical Formulas

and Chemical

CompoundsHeart cell rhythm depends on the opening and closing of a complex series of valves on the cell membrane, called ion channels. Some valves let certain ions like potassium (K+) flow out, others let different ions like sodium (Na+) flow in. There are also pumps that actively move ions one direction or another.

IonsIons• Cation: A positive ion

• Mg2+, NH4+

• Anion: A negative ion

• Cl, SO42

• Ionic Bonding: Force of attraction between oppositely charged ions.

Predicting Ionic ChargesGroup 1Group 1::Lose 1 electron to form Lose 1 electron to form 1+1+ ions ions

HH++ LiLi++ NaNa++ KK++

Predicting Ionic ChargesGroup 2Group 2::Loses 2 electrons to form Loses 2 electrons to form 2+2+ ions ions

BeBe2+2+ MgMg2+2+ CaCa2+2+ SrSr2+2+ BaBa2+2+

Predicting Ionic ChargesGroup 13Group 13:: Loses 3 Loses 3 electrons to form electrons to form 3+3+ ions ions

BB3+3+ AlAl3+3+ GaGa3+3+

Predicting Ionic ChargesGroup 14Group 14:: Lose 4 Lose 4 electrons or gain electrons or gain 4 electrons?4 electrons?

Neither! Neither! Group 14 Group 14 elements rarely elements rarely form ions.form ions.

Predicting Ionic ChargesGroup 15Group 15:: Gains 3 Gains 3 electrons to form electrons to form 3-3- ions ions

NN3-3-

PP3-3-

AsAs3-3-

Nitride

Phosphide

Arsenide

Predicting Ionic ChargesGroup 16Group 16:: Gains 2 Gains 2 electrons to form electrons to form 2-2- ions ions

OO2-2-

SS2-2-

SeSe2-2-

Oxide

Sulfide

Selenide

Predicting Ionic ChargesGroup 17Group 17:: Gains 1 Gains 1 electron to form electron to form 1-1- ions ions

FF1-1-

ClCl1-1-

BrBr1-1-Fluoride

Chloride

Bromide

II1-1- Iodide

Predicting Ionic ChargesGroup 18Group 18:: Stable Stable Noble gases Noble gases do do notnot form ions! form ions!

Predicting Ionic ChargesGroups 3 - Groups 3 - 1212::

Many Many transitiontransition elements elements have more than one possible oxidation have more than one possible oxidation state.state.Iron(II) = Fe2+ Iron(III) = Fe3+

Predicting Ionic ChargesGroups 3 - Groups 3 - 1212::

Some Some transitiontransition elements elements have only one possible oxidation state.have only one possible oxidation state.

Zinc = Zn2+ Silver = Ag+

Binary Ionic Compounds

• Binary ionic compounds means two ions,

• one that is positive in charge (cation)

• one that is negative in charge (anion)

• that react to form a compound.

Naming Ionic Binary Compounds

1. The ion with the positive charge (cation) is always written before the ion with the negative charge (anion)

2. The first word is the name of the element of which the cation originally came. (Example: Na+ would be called Sodium)

3. The last word is the name of the element of which the anion originally came. (Example: Cl- would become chlorine, but the first part of the word is used and -ide is added to the end, so the last word would be Chloride.)

4. Put the two words together and that is the name of the compound. (Example: Na+ and Cl- would become Sodium Chloride.)

Naming Ionic CompoundsNaming Ionic Compounds• 1. Cation first, then anion

• 2. Monatomic cation = name of the element

• Ca2+ = calcium ion

• 3. Monatomic anion = root + -ide• Cl = chloride

• CaCl2 = calcium chloride

Naming Ionic Compounds(continued)

Naming Ionic Compounds(continued)

• - some metal forms more than one cation

• - use Roman numeral in name

• PbCl2

• Pb2+ is cation

• PbCl2 = lead(II) chloride

Metals with multiple oxidation Metals with multiple oxidation statesstates

Polyatomic Ions

• Polyatomic Ions are ions that contain a number of ions.

• There is no way to learn how to write their names, except to commit them to memory

Common Polyatomic Ions (VIP)

Ion Name Ion Name

NH4+ Ammonium O2

-2 Peroxide

NO2- Nitrite CrO4

-2 Chromate

NO3- Nitrate Cr2O7

-2 Dichromate

SO3-2 Sulfite MnO4

- Permanganate

SO4-2 Sulfate C2H3O2

- Acetate

HSO4- Hydrogen Sulfate ClO4

- Perchlorate

OH- Hydroxide ClO3- Chlorate

CN- Cyanide ClO2- Chlorite

PO4-3 Phosphate ClO- Hypochlorite

HPO4- Hydrogen Phosphate HCO3

- Hydrogen Carbonate

H2PO4- Dihydrogen Phosphate CO3

-2 Carbonate

Writing Ionic Compound Formulas

Example: Ammonium sulfate

1. Write the formulas for the cation and anion, including CHARGES!

NHNH44++ SOSO44

2-2-2. Check to see if charges are balanced.

3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion.

Not balanced!

( )( )22

Writing Ionic Compound Formulas

Example: Iron(III) chloride

1. Write the formulas for the cation and anion, including CHARGES!

FeFe3+3+ClCl--2. Check to see if charges are balanced.

3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion.

Not balanced!

33

Writing Ionic Compound Formulas

Example: Aluminum sulfide1. Write the formulas for the cation and anion, including CHARGES!

AlAl3+3+ SS2-2-2. Check to see if charges are balanced.

3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion.

Not balanced!

22 33

Writing Ionic Compound Formulas

Example: Magnesium carbonate1. Write the formulas for the cation and anion, including CHARGES!

MgMg2+2+ COCO332-2-2. Check to see if

charges are balanced.

They are balanced!

Writing Ionic Compound Formulas

Example: Zinc hydroxide

1. Write the formulas for the cation and anion, including CHARGES!

ZnZn2+2+ OHOH--2. Check to see if charges are balanced.

3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion.

Not balanced!

( )( )22

Writing Ionic Compound Formulas

Example: Barium nitrate

1. Write the formulas for the cation and anion, including CHARGES!

BaBa2+2+ NONO33--2. Check to see if charges are

balanced.

3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion.

Not balanced!

( )( ) 22

Writing Ionic Compound Formulas

Example: Aluminum phosphate1. Write the formulas for the cation and anion, including CHARGES!

AlAl3+3+ POPO443-3-2. Check to see if charges are

balanced.

They ARE balanced!