Chapter 15 Ionic Bonding and Ionic Compounds. What is an Ionic Bond?

Chapter 15Ionic Bonding and Ionic

Compounds

What is an Ionic Bond?

Ionic Bond Bond formed between a metal and

nonmetal.

Why do atoms bond? Atoms bond in order to acquire a full set

of valence electrons. Most of the time this is 8 . This is known

as the octet rule. Atoms will gain, lose or share in

order to attain a full set of electrons

Valence Electrons The electrons responsible for the

chemical properties of atoms are those in the outer energy level. These electrons are called the valence electrons.

Valence electrons - The electrons in the outer energy level

Electron Configuration

Electron Configuration…Maybe you learned it this way

Electron Configurations for Cations

Metals lose electrons to attain noble gas configuration.

They make positive ions (cations) If we look at the electron configuration,

it makes sense to lose electrons: Na 1s22s22p63s1 1 valence electron Na1+ 1s22s22p6 noble gas configuration

Electron Configurations for Anions

Nonmetals lose electrons to attain noble gas configuration.

They make negative ions (anions) If we look at the electron configuration, it

makes sense to lose electrons: F 1s22s22p5 2 valence electrons F-1 1s22s22p6 noble gas configuration

Keeping Track of Electrons Atoms in the same column...

–Have the same valence electrons. LABEL!

Bohr Model of the AtomThe Bohr Model has an atom consisting of a small, positively-charged nucleus orbited by negatively-charged electrons.

• 1st shell: 2 electrons

• 2nd shell: 8 electrons

• 3rd shell: 18 electrons

Example: Bohr Model of Nitrogen

CHEM-IS-TRYDraw the Bohr Model of Fluorine

Electron Dot diagrams A way of keeping track of

valence electrons. How to write them? Write the symbol. Put one dot for each

valence electron Don’t pair up until they

have to (Hund’s rule)

X

The Electron Dot diagram for Nitrogen

Nitrogen has 5 valence electrons.

First we write the symbol.

NThen add 1 electron at a time to each side.Until they are forced to pair up.

Write electron dot diagrams: Na

Mg

C

O

Properties of Ionic Compounds A regular repeating arrangement of

ions in the solid: this is known as a lattice. Structure is rigid.

High melting points

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.

Therefore, they have the ability to conduct electricity

Ionic Compounds dissolved in water conduct

Completing the Circuit