1. The Attachment Between Atoms
atoms combine to form
ionic bonds covalent bonds
(M + NM) (NM + NM)
chemical bond – a mutual electrical attraction between the nuclei and valence electrons of two atoms that binds the atoms together

2. Ionic Bonding cation and anion
ionic bond – when electrons are taken by one atom from another atom
metal and a nonmetal
NaCl
cation and anion
(The charges are “hidden” to make a neutral compound.)

3. Ionic Bonding: taking of electrons
Na 11e-
F 9e-
Na+ 10e- STABLE!!!
F- 10e- STABLE!!! 3s 3s 2p 2p 2s 2s 1s 1s

4. + - I’m Positive! I’m Negative A metal atom A metal ion A nonmetal ion
A nonmetal atom
I’m Positive!
I’m Negative + -

5. I’m Positive! I’m Negative
A metal ion
A nonmetal ion
I’m Positive!
I’m Negative
When a metal and a nonmetal atom are around each other there is the opportunity for….
…the transfer of electrons producing ions that would like to cling to each other.

6. The simplest ratio of the packed ions is called:
The Formula Unit Ex: NaCl

7. Ions cations (+) anions (-)
monatomic ions – ions formed from one atom Examples: Na+ or O-2
polyatomic ions - ions formed from two or more atoms bonded together
Examples: NH4+ or SO4-2

8. Naming Ions monatomic ions polyatomic ions
Cations – named like the atom, only add ion to it
Example: Na+
is the sodium ion
Anions – remove the ending to the atom name and add –ide and ion to it
Example: Cl-
is the chlorine
+ide ion
or the chloride ion
polyatomic ions
You do not determine their names, you memorize them

9. Ionic Compounds solid at room temperature
high melting points (thus are usually solid at RT)
formula unit represents the lowest ratio of ions that combine to form a neutral compound
most are crystalline solids
when dissolved in water, the ionic compounds will break up into ions (dissociate)
the solutions of ionic compounds will conduct electricity (electrolytes)

10. Dissociation solid placed in water hydrated ions (surrounded by water)
dissociation – when an ionic compound dissolves to break apart into hydrated ions

11. Dissociation
Click on the picture to see a short clip.

12. Electrolytes and Nonelectrolytes
When an ionic compound dissolves to produce ions, it is called an electrolyte because it conducts electricity in water.
When an compound does not dissolve to produce ions, it is called a nonelectrolyte because it does not conduct electricity in water.
Click on the picture to see a short clip.

13. Covalent Bonding
covalent bond – when electrons are shared between two atoms
two nonmetals
No ions formed! (no electrons are taken)

14. Covalent Compounds Also called molecular compounds
solid, liquid, or gas at room temperature
low melting points
molecular formula represents the actual ratio of atoms that combine to form a neutral compound
when dissolved in water, the molecular compounds DO NOT break up into ions
the solutions of molecular compounds DO NOT conduct electricity (nonelectrolytes)

15. When a nonmetal and another nonmetal atom are around each other there is the opportunity for….
…the sharing of electrons producing molecules in which the atoms like to cling to each other.

16. The formation of a bond between two nonmetal atoms.
Atoms sufficiently far apart to have no interaction

17. Figure 5 Page 179

18. The two fundamental types of bonds.
Pure Covalent
The two fundamental types of bonds.
Ionic

19. There is another type of bond, not purely covalent and not purely ionic.
Nonpolar Covalent
Pure Covalent
Polar Covalent
Ionic

20. Sharing of Electrons
How would you know if an electron is going to be taken by one atom from another?
Is there ever a time in which the electron is not taken but shared?
Is the electron always shared equally?

21. Electronegativity
electronegativity – a measure of the ability of an atom in a chemical compound to attract electrons from another atom in the compound
The difference in electronegativity values for two atoms will indicate whether the two atoms form an ionic bond or a polar or nonpolar covalent bond.

22. Electronegativity Differences
< 0.3 nonpolar covalent
0.3 to 1.7 polar covalent
> 1.7

23. Ionic, Polar Covalent, or Nonpolar Covalent?
What kind of bond would each pair form?
N and S
S and C
Mg and Cl
C and F
Ba and O

24. Octet Rule
octet rule – most atoms will gain or lose electrons to have 8 valence electrons (e- in the highest energy level)
Exceptions: H, He, Li, Be, B, and some atoms P and higher on the periodic table
Why is an atom like Ca not stable with 2 valence electrons?
How many would it have to lose to have 8?

25. Valence Shell Electron Pair Repulsion Theory VSEPR Theory
Repulsion between the sets of valence-level electrons surrounding an atom causes these sets to be oriented as far apart as possible.

26. Regions of Electron Density
What is a Region of electron density?
Single bond (2e- connecting 2 atoms)
Double bond(4e- connecting 2 atoms)
Triple bond(6e- connecting 2 atoms)
Lone pair (unbonded pair) (2e- alone on an atom)

27. LINEAR 180o 2 Regions of Electron Density 2 Bonds
bonded pair of electrons
bonded pair of electrons

28. TRIGONAL PLANAR 120o 3 Regions of Electron Density 3 Bonds
3 bonded pairs of electrons

29. BENT 119o 3 Regions of Electron Density 2 Bonds & 1 Lone Pair
2 bonded pairs of electrons
1 lone pair of electrons

30. TETRAHEDRAL 109.5o 4 Regions of Electron Density 4 Bonds
4 bonded pairs of electrons

31. TRIGONAL PYRAMIDAL 107o 4 Regions of Electron Density 3 Bonds & 1 Lone Pair
1 lone pair of electrons
3 bonded pairs of electrons

32. BENT 105o 4 Regions of Electron Density 2 Bonds & 2 Lone Pairs

33. All of these have 4 regions of electron density
(although the number of bonded pairs is different)

34. TRIGONAL BIPYRAMIDAL 120o & 90o 5 Regions of Electron Density 5 Bonds

35. You don’t have to know this!
SEE-SAW 120o & 90o 5 Regions of Electron Density 4 Bonds & 1 Lone Pair
You don’t have to know this!

36. You don’t have to know this!
T-SHAPED 120o & 90o 5 Regions of Electron Density 3 Bonds & 2 Lone Pairs
You don’t have to know this!

37. You don’t have to know this!
LINEAR 180o 5 Regions of Electron Density 2 Bonds & 3 Lone Pairs
You don’t have to know this!

38. OCTAHEDRAL 90o 6 Regions of Electron Density 6 Bonds
SF6

39. You don’t have to know this!
SQUARE PYRAMIDAL approximately 90o 6 Regions of Electron Density 5 Bonds & 1 Lone Pair
BrF5
You don’t have to know this!

40. SQUARE PLANAR 90o 6 Regions of Electron Density 4 Bonds & 2 Lone Pairs
ICl4-