Chemistry Chapter Chemistry Chapter 1515

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 ike 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.

IonsIonsIonsIons• CationCation: A positive ion: A positive ion

• MgMg2+2+, NH, NH44++

• AnionAnion: A negative ion: A negative ion

• ClCl, SO, SO4422

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

Predicting Ionic ChargesPredicting Ionic Charges

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

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

Predicting Ionic ChargesPredicting Ionic Charges

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

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

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

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

Lead (Pb) and Tin (Sn) are metals and they lose electrons: Pb2+, Pb 4+, Sn2+ and Sn4+.

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

NN3-3-

PP3-3-

AsAs3-3-

Nitride

Phosphide

Arsenide

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

OO2-2-

SS2-2-

SeSe2-2-

Oxide

Sulfide

Selenide

Predicting Ionic ChargesPredicting 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 ChargesPredicting Ionic ChargesGroup 18Group 18:: Stable Noble Stable Noble gases gases do notdo not form ions!form ions!

Predicting Ionic ChargesPredicting Ionic ChargesGroups 3 - Groups 3 - 1212::

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

To show which ion it is we use Roman numerals in naming ions with more than one possible charge!!

Predicting Ionic ChargesPredicting Ionic ChargesGroups 3 - Groups 3 - 1212::

Some Some transitiontransition elements elements have only one possible oxidation have only one possible oxidation state.state.Zinc = Zn2+ Silver = Ag+

Writing Ionic Compound Writing Ionic Compound FormulasFormulas

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 Writing Ionic Compound FormulasFormulas

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 Writing Ionic Compound FormulasFormulas

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 Writing Ionic Compound FormulasFormulas

Example: Aluminum sulfide

1. 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 Writing Ionic Compound FormulasFormulas

Example: Magnesium carbonate

1. 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 Writing Ionic Compound FormulasFormulas

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 Writing Ionic Compound FormulasFormulas

Example: Aluminum phosphate

1. 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!

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

• 2. Monatomic cation = name of 2. Monatomic cation = name of the elementthe element

• CaCa2+2+ = calcium = calcium ionion

• 3. Monatomic anion = 3. Monatomic anion = rootroot + + -ide-ide

• ClCl = chlor = chlorideide

• CaClCaCl22 = calcium chlor= calcium chlorideide

Naming Ionic CompoundsNaming Ionic Compounds(continued)(continued)

Naming Ionic CompoundsNaming Ionic Compounds(continued)(continued)

• -- some some metal forms more than one metal forms more than one cationcation

• -- use use Roman numeralRoman numeral in namein name

• PbClPbCl22

• PbPb2+2+ is cationis cation

• PbClPbCl22 = lead( = lead(IIII) chloride) chloride

Metals with multiple oxidation Metals with multiple oxidation statesstates

Naming Binary CompoundsNaming Binary CompoundsNaming Binary CompoundsNaming Binary Compounds• -- Compounds between two Compounds between two nonmetalsnonmetals• -- First element First element in the formula is in the formula is named firstnamed first..• -- Second element Second element is named as if it were an is named as if it were an

anionanion..• -- Use prefixesUse prefixes• -- Only use Only use monomono on second element - on second element -

PP22OO55 ==COCO22 = =

CO =CO =

NN22O =O =

didiphosphorus phosphorus pentpentoxideoxide

carbon carbon didioxideoxide

carbon carbon monmonoxideoxide

didinitrogen nitrogen monmonoxideoxide