IONIC BONDING

Happens when an atom of a nonmetaltakes one or more electrons

from an atom of a metalso both atoms end up with

eight valence electrons

An electrical attraction between two oppositely charged atoms or groups of atoms.

The Octet Rule

• The octet rule says that atoms can become stable by having eight electrons in their outer energy level, as shown in the noble gas, Neon, (or two electrons in the case of some of the smallest atoms).

Electron Dots For Cations Metals will have few valence electrons These will come off

Ca

Electron Dots For Cations Metals will have few valence electrons These will come off Forming positive ions

Ca2+

Electron Dots For Anions

Nonmetals will have many valence electrons.

They will gain electrons to fill outer shell.

P P3-

IONIC COMPOUNDS

metal with nonmetal + ion - ion Ca+ion anion

Predicting Oxidation Number or Charge from Periodic Table

Forming Cations

metals lose e- form cations oxidation #

group 1A lose 1 +1 charge 1 + group 2A lose 2 +2 charge 2 + group 3A lose 3 +3 charge 3 + group 4A lose 4 +4 charge 4 +

Forming Anions

Non-metals gain e- form anions oxidation #

group 7A gain 1 -1 charge 1 -

group 6A gain 2 -2 charge 2 - group 5A gain 3 -3 charge 3 -

1

7

4

5

6

2

3

+1

+2

+3 +4

-3 -2 -1

0

+2

+2

+3

+1

Oxidation Numbers

Neutral atoms come near each other.

Electron(s) are transferred from the Metal atom to the Non-metal atom.

They stick together because of electrostatic forces, like magnets.

IONIC BONDING

Steps for writing ionic bond formulas 1. Determine the oxidation numbers

for the two elements or ions.

Ca = +2, Cl = -1

Steps for writing ionic bond formulas 2. Write the chemical symbols in the

correct order, with the metal ion first and write the oxidation numbers as superscripts. Ca 2+ Cl -1

Ca 2+ Cl 1-

3. Crisscross the numbers only—not the charge signs—writing the oxidation number of one element as a subscript for the other. Don’t write number 1 either.

Ca 1 Cl 2

Steps for writing ionic bond formulas

Ca Cl2

4. Determine whether the formula is in its simplest form. Reduce the subscripts to the simplest from by dividing by a common denominator.

CaCa+2+2 OO-2-2

CaCa22 OO22 = Ca= Ca22OO22

CaOCaO

Steps for writing ionic bond formulas

5. Check the formula by calculating the total positive and negative charges and confirming that the total charge on the compound is zero.

CaCl 2

Steps for writing ionic bond formulas

 Oxidation Number

 

Subscript

   

Calcium (+2) x (1) = +2

Chlorine (-) x (2) = -2

Practice these!

magnesium and oxygen aluminum and bromine sodium and sulfur potassium and nitrogen

MgO

AlBr3

Na2S

K3N

More Practice!

potassium bromidecalcium oxideSilver fluoride

KBrCaOAgF

Polyatomic ions

Groups of atoms that stick together as a unit, and have a charge

PO43- phosphate

CO32- carbonate

C2H3O41- acetate

Names often end in –ate or –ite

6. POLYATOMIC IONS ACT JUST LIKE ANY OTHER NEGATIVE ION WHEN BONDINGTreat polyatomic ion as single unit—don’t change it in any way!

Steps for writing ionic bond formulas

Steps for writing ionic bond formulas

polyatomic ions are enclosed in parenthesis if taken more than once in the formula. A subscript outside the parenthesis multiplies everything inside.

Steps for writing ionic bond formulas

Steps for writing ionic bond formulas

potassium hydroxide

zinc (II) carbonate

barium chlorate

aluminum phosphate

Practice

KOHKOH

ZnCOZnCO33

Ba(ClOBa(ClO33))22

AlPOAlPO44

calcium acetate

sodium nitrate

aluminum hydroxide

ammonium phosphate

More Practice

Ca(CCa(C22HH33OO22)) 2 2

NaNONaNO33

Al(OH)Al(OH) 3 3

(NH(NH44))3 3 POPO44

Naming Ionic Compounds1. name cation - then anion

2. if anion (nonmetal) is a single element ….. then name ends in “-ide”

3. If metal have more than one possible charge (include roman numeral in parenthesis to give charge)*

*All metals except: Ag+1, Zn+2, Cd+2, Al+3

Naming Ionic Compounds

Na2O

Mg(OH)2

Al(NO3)3

NH4Cl

Practice (no transitional metals)

Sodium oxideSodium oxide

Manganese (II) oxideManganese (II) oxide

Aluminum nitrateAluminum nitrate

Ammonium chlorideAmmonium chloride

Sn(ClO3)4

Cu2CO3

Fe2O3

NiSO4

Practice with transitional metals

Tin(IV) chlorateTin(IV) chlorate

Copper (I) carbonateCopper (I) carbonate

Iron (III) oxideIron (III) oxide

Nickel (II) sulfateNickel (II) sulfate

Hint: look at the subscript in the anion to predict the metal oxidation number.

Properties of Ionic Compounds Crystalline structure. A regular repeating arrangement of

ions in the solid. Ions are strongly bonded. Structure is rigid. High melting points- because of

strong forces between ions.

Crystalline structure

3 dimension

The repeating unit is called the unit cell

Crystalline structure

+

+

+ +

+

+

++

+

--

--

- --

--

The POSITIVE CATIONS

stick to the NEGATIVE ANIONS,

like a magnet.

Ionic solids are brittle

+ - + -+- +-

+ - + -+- +-

Ionic solids are brittle

+ - +-

+- +-+ - + -+- +-

Strong Repulsion breaks crystal apart.

Cubic

Body-Centered Cubic

Face-Centered Cubic

Do they Conduct? Conducting electricity is allowing

charges to move. In a solid, the ions are locked in place. Ionic solids are insulators. When melted, the ions can move

around. Melted ionic compounds conduct. First get them to 800ºC. Dissolved in water they conduct.