Ionic and Metallic Bonding

And how!

1/5/12

• Objective: To review the fundamentals of ions and learn about ionic bonding

• Do now: Do the hokey pokey. Turn yourself around. – Then write down what a valence electron is and

how many aluminum and gold have. (4 minutes!)• Le homework: – Read Ch. 7.1, answer pg 193 # 3-11

Valence electrons

• The electrons in an atoms highest energy level are called valence electrons– We’ll revisit this later.

• S and P block: Valence electrons = group #• D and F block: all elements have 2 valence e-s

Octet rule• Why do atoms give up and receive electrons?• BIG IDEA: – Octet rule: atoms give up and receive electrons in

order to achieve a full valence shell – A full valence shell has 8 e-s

Cations

• Metals tend to lose electrons when they form ions– less electrons than protons– overall positive charge – Positive ions are called cations

Anions

• Non-metals tend to gain electrons when they form ions– more electrons than protons– overall negative charge– Negative ions are called anions

1/6/12

• Objectif: To understand the electron configuration of ions

• Do now: How many electrons do each of the following ions have? – Na+, F-, Al3+, O-2, Mg2+

• Do Later: Read 7.2, pg 196 #12 & 13, Pg 199 # 14-22

Hw 1/5/12

3) Valence electrons of rep. element = group #4) Metals gain electrons, non-metals lose e-s5) Atoms lose electrons to form cations6) Atoms gain electrons to form anions7) a. 1 b. 4 c. 2 d. 68) 9) a. lose 2 b. gain 1 c. lose 3 d. gain 210) Potassium ion K+; zinc ion Zn2+; fluoride ion F-

11) Cd2+ = 1s22s22p63s23p64s23d104p64d10

Electron Dot Structures

• Electron dot structure = chemical symbol of an atom surrounded by dots representing valence electrons.

– Ex: Lithium (1 valence e-)

– Zinc (2 valence e-s)

– Carbon (4 valence e-s)

– Bromine (7 valence e-s)

Noble Gas Configurations

• Noble gases are in group 8A– 8 valence electrons = full octet– Valence shell = ns2np6

Neon: 1s22s22p6

Argon: 1s22s22p63s23p6

Krypton: 1s22s22p63s23p64s23d104p6

Noble Gas Configurations• Old idea: Atoms gain or lose electrons to form

ions with full octets in their valence shell

• New idea: Atoms with full octets in their valence shell have electron configurations similar to a noble gas.

Sodium Neon

Electron configuration of ions

• How do I write the electron configuration of an ion? – Calculate the number of electrons in the ion– Proceed as usual

• Example: Al Al3+ + 3e-

– Al (13 e-): 1s22s22p63s23p1

– Al3+ (10 e-): 1s22s22p6 = Ne: 1s22s22p6

Electron configuration of ions

• Exception: Metals in periods 4 and higher lose electrons from their highest energy levels not their highest energy orbitals.

• Example: – Iron (26 e-): 1s22s22p63s23p64s23d6

– Fe2+: 1s22s22p63s23p63d6

– Why not lose higher energy e-s in 3d?• Because 4s2 are the valence electrons. Losing them leaves

you with a full third valence shell.