1. The Name’s BOND…….
Chemical Bond

2. Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 electrons
C would like to
N would like to
O would like to
Gain 4 electrons
Gain 3 electrons
Gain 2 electrons

3. Cations/Anions What kind of atoms LOSE electrons and become positive?
What kind of atoms GAIN electrons and become negative?

4. Diatomic Molecules
Always exist in a chemical bond with another atom, even if the atom is of the same element
H2 , N2 , O2 , F2 , Cl2 , Br2 , I2

5. Chemical Bond Involves 2 atoms
Mutual, electrical attraction between nuclei and valence electrons of 2 atoms

6. Chemical bonds: an attempt to fill electron shells
Ionic bonds –
Covalent bonds –
Metallic bonds

7. IONIC BOND bond formed between two ions by the transfer of electrons
IONIC BOND bond formed between two ions by the transfer of electrons. ELECTRON STEALING !

8. Ionic Bonds: One Big Greedy Thief Dog!

10. Formation of Ions from Metals
Ionic compounds result when metals react with nonmetals
Metals lose electrons to match the number of valence electrons of their nearest noble gas
Positive ions form when the number of electrons are less than the number of protons
Group 1 metals  ion 1+
Group 2 metals  ion 2+
Group 13 metals  ion 3+

11. Ionic Bonds
Between atoms of metals and nonmetals with very different electronegativity
Huge difference in electronegativity
Electronegativity value > 1.7
Bond formed by transfer of electrons
Produce charged ions
Form between elements located on opposite sides of the periodic table

12. Ionic Bonds (cont.) Conductors High melting point. Water soluble
Crystallize (form crystals)
Examples; NaCl, CaCl2, K2O

13. 1). Ionic bond – electron from Na is transferred to Cl, this causes a charge imbalance in each atom. The Na becomes (Na+) and the Cl becomes (Cl-), charged particles or ions.

15. COVALENT BOND bond formed by the sharing of electrons Electron sharing!

16. Covalent Bonds

17. Covalent Bond
Between nonmetallic elements of similar electronegativity.
Small electronegativity difference <1.7
Formed by sharing electron pairs,
Formed between elements on the same side of the periodic table.

18. Covalent Bond (cont.) Stable non-ionizing particles
Poor electrical conductors
Brittle, nonmetals, low melting point
Examples; O2, CO2, C2H6, H2O,

19. Partial Charges Apply ONLY to COVALENT bonds
Results when there is unequal sharing between 2 atoms
Indicates electronegativity difference between bonded atoms

20. when electrons are shared equally, small electronegativity difference
NONPOLAR COVALENT BONDS
when electrons are shared equally, small electronegativity difference
All diatomics
H2 or Cl2

21. when electrons are shared but shared unequally
POLAR COVALENT BONDS
when electrons are shared but shared unequally
H2O

22. Polar Covalent Bonds--More
One atom “keeps” electrons closer to it
Electrons tend to reside around one atom more than the other atom
Electrons still remain distributed between the 2 atoms-- unequal

23. Polar Covalent Bonds: Unevenly matched, but willing to share.

24. Example: Cl2 , H2O

26. Multiple Covalent Bonds
Single
1 bond between 2 atoms
2 electrons shared
Ex. H2
Double
2 bonds between 2 atoms
4 electrons shared
Ex. O2

27. Multiple Covalent Bonds (cont.)
Triple
3 bonds between 2 atoms
6 electrons shared
Ex. N2

28. Example: H2O, KI

29. Identify Bond type, Draw Lewis Structure to show bonding
NaCl, CO

30. METALLIC BOND bond found in metals; holds metal atoms together very strongly

31. Electrons Localized: Delocalized: Electrons hang out in a local area
Restricted to an atom/ion or shared between atoms
Delocalized:
Electrons not attached to a particular area
Electrons are able to travel and move among atoms

32. Metallic Bonds Formed between atoms of metallic elements
Between atoms on left side of periodic table
Electronegativities are approximately equal
Electron cloud around atoms, delocalized electrons
Valence electrons shared among multiple atoms, “neighbors”
Electrons move through the whole metal, can jump between energy levels to create conduction bands.

33. Metallic Bonds (cont.)
Delocalized electrons result in good electrical and thermal conductors
3-D network of metal ions and electron sea
Examples; Na, Fe, Al, Au, Co

34. Metallic Bond, A Sea of Electrons

35. Metallic Bonds: Mellow dogs with plenty of bones to go around.

36. Alloys Metallic compounds with 2 different elements
Enhances metallic characteristics
Ex. Sterling silver (approx %Ag, other metal—Cu)
Brass (Cu and Zn)
Stainless steel (contains chromium, prevents corrosion, structural component)

38. What is the point of chemical bonding?
Physical/chemical properties vary based on
Structure
Bond type
Ionic Bonds
High melting point
High boiling point
Covalent Bonds
Lower melting point
Lower boiling point