Ionic Compounds are formed from a metallic cation, and a non-metallic anion

Ionic Bonding Anions and cations are held together by opposite charges. Ionic compounds are called salts . The bond is formed through the transfer of electrons. Electrons are transferred to achieve a noble gas configuration. (very stable)

Anions and cations are held together by opposite charges.

Ionic compounds are called salts .

The bond is formed through the transfer of electrons.

Electrons are transferred to achieve a noble gas configuration. (very stable)

Example 1 . . . . . . . . Na + Cl Na + + . . . . . . . Cl . - Na has 1 valence electron because it is in Group 1 Cl has 7 valence electrons because it is in Group 17

Example 1 Na + Cl - Na gives his one valence electron to Cl. Now both atoms are happy. They each have a stable set-up of electrons like noble gases. How many do they need in their valence shell to be stable?

Ionic Bonding All the electrons must be accounted for! Ca P

All the electrons must be accounted for!

Ionic Bonding Ca P Sometimes atoms can’t satisfy each other in a one to one ratio

Making Formulas Ca +2 P Notice Ca is happy but P still needs one more electron. So watch what happens.

Making Formulas Ca +2 P Ca

Making Formulas Ca +2 P -3 Ca But what about the 2nd Ca?

Making Formulas Ca +2 P -3 Ca P

Making Formulas Ca +2 P -3 Ca +2 P OK, 2nd Ca is Happy but 2nd P is not now!

Making Formulas Ca +2 Ca +2 Ca P -3 P

Making Formulas Ca +2 Ca +2 Ca +2 Finally everyone’s happy! P -3 P -3

Making Formulas Ca 3 P 2 So what’s the formula for this Compound? Now complete your Ionic Formulas Worksheet.

Steps to remember 1)Get charges for the cation and anion.(Look at the Periodic Table) Cation always comes first! 2)Put polyatomics in parenthesis. 3)Balance the charges so that they add up to zero by using subscripts. (Cross method)

Writing Formulas: The Cross-Out Method Steps to Remember: 1) Get charges for the cation and anion. Cation always comes first! 2)Balance the charges so that they add up to zero by using subscripts. (cross-out method)

Steps to Remember:

1) Get charges for the cation and anion. Cation always comes first!

2)Balance the charges so that they add up to zero by using subscripts. (cross-out method)

Reminder: Get charges from the Periodic Table +2 +1 +3 -3 -2 -1

Example: Ba and Br Cation? Anion? Ba +2 Br -1 BaBr 2 (The one is understood) Now complete your ionic cross-out worksheet.

Polyatomic Ions Groups of atoms that stay together and have a charge. Found on p. 7 of your Chemistry Reference Tables Name Charge Formula

Groups of atoms that stay together and have a charge.

Found on p. 7 of your Chemistry Reference Tables

How Do We Use Polyatomic Ions? When writing them as either cation or anion we ... ... put parenthesis around the ion. Example: ammonium becomes (NH 4 ) + So ammonium chloride would become (NH 4 )Cl

When writing them as either cation or anion we ...

... put parenthesis around the ion.

Example: ammonium becomes (NH 4 ) +

So ammonium chloride would become (NH 4 )Cl

Example with Polyatomic Ions Calcium and nitrate Cation Anion Ca +2 NO 3 -1 Ca(NO 3 ) 2 Remember: Polyatomic ion goes in parentheses.

Writing Names Step 1 – Separate cation and anion from formula CuBr 2 Cu 2+ Br -

Step 1 – Separate cation and anion from formula

CuBr 2

Cu 2+ Br -

Step 2 – Name Check for the need for a roman numeral in the name. Transition element? Yes “Special Case” on stair-step? Yes

Step 2 – Name Ex : Cu 2+ Br - Copper (II) Bromide

Ex : Cu 2+ Br -

Copper (II) Bromide

Things to look for If cations have (), the number is their charge. If anions end in -ide they are probably off the periodic table If anion ends in -ate or -ite it is polyatomic

If cations have (), the number is their charge.

If anions end in -ide they are probably off the periodic table

If anion ends in -ate or -ite it is polyatomic

Properties of Ionic Solids High lattice energy   high melting T 3D ionic lattice  brittleness Ions   electrical conductivity (when molten) solubility in polar solvents (eg H 2 O)

Properties of Ionic Compounds Crystalline structure. A regular repeating arrangement of ions in the solid. Ions are strongly bonded. Structure is rigid.

Crystalline structure.

A regular repeating arrangement of ions in the solid.

Ions are strongly bonded.

Structure is rigid.

Crystalline structure

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. Dissolved in water 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.

Dissolved in water they conduct.

Ionic solids are brittle + - + - + - + - + - + - + - + -

Ionic solids are brittle Strong Repulsion breaks crystal apart. + - + - + - + - + - + - + - + -

Strong Repulsion breaks crystal apart.