1. CHEMICAL BONDING What is it?
Mod.H U.3 L.3

2. Identify the elements in these compounds
Identify the elements in these compounds. Predict whether the elements are similar to each other. Why?
C6H12O6
C2H5OH
C6H8O6
C6H8O7

3. Carbon, hydrogen, oxygen. They are similar
C6H12O6 (glucose - a sugar)
C2H5OH (ethyl alcohol – an alcohol)
C6H8O6 (vitamin C – found in citrus fruits)
C6H8O7 (citric acid - found in citrus fruits)

4. Chemical Bonding is: The joining of atoms, or
The re-arrangement of atoms
- to form new substances

5. Examples:
A silver spoon tarnishes. The silver reacts with sulfur in the air to make silver sulfide, or tarnish. 2 Ag + S Ag2S

6. An iron bar rusts. The iron reacts with oxygen in the air to make rust
An iron bar rusts. The iron reacts with oxygen in the air to make rust. 4 Fe + 3 O Fe2O3

7. Methane combines with oxygen in the air to make carbon dioxide and water vapor. CH4 + 2O CO2 + 2 H2O

8. An antacid (calcium hydroxide) neutralizes stomach acid (hydrochloric acid):
Ca(OH)2 + 2HCl CaCl2 + 2H2O

9. Sugar breaks down when fermented to give:
C6H12O C2H5OH + 2 CO2
(glucose) (ethyl alcohol)

10. Carbon burns in air(oxygen) to give carbon dioxide
C + O CO2

11. Chemical Bonds The force of attraction that holds atoms together
(electromagnetic / electrostatic)

12. How are bonds formed?
Bonds are formed by the outer shell or valence electrons of an atom. * Review Lewis models of atoms!

13. For sodium? (Na) For calcium? (Ca) For chlorine? (Cl) For Carbon? (C)
What are the valences?
For sodium? (Na)
For calcium? (Ca)
For chlorine? (Cl)
For Carbon? (C)

14. Valences for transition metals
Either 1, 2 or both, sometimes 3!
Iron Fe shows all 3 valences!
Fe(I), Fe(II), & Fe (III)

15. Valences for nonmetals
Subtract 10 from the group number
(in your book / P. table)
C = 14-10=4
O = ? Cl = ? N = ?

16. The Octet Rule
Atoms will form bonds with other atoms to get a full outer shell (8). Is most stable
Noble gases already have 8!
So are unreactive or inert.

17. H and Li need only 2 valence electrons to complete the k-shell
Exceptions!
H and Li need only 2 valence electrons to complete the k-shell
(also He?)

18. Organizing electrons
When bonding, atoms will attain the stable octet state by either:
Losing (an) electron(s)
Gaining (an) electron(s), or
Sharing electrons

19. The farther away from the nucleus an electron is, the more energy it has, and the less strongly it is pulled to the nucleus.
So, it’s easier to lose it !

20. So…..
How are bonds formed?

21. 1. Atoms Lose an electron: form positive ion - cation

22. 2. Gain an electron – form a negative ion - anion

23. Na+Cl- crystal structure (cubic)

24. 3. Share electrons

25. HOMEWORK! QUIZ!!

26. Physical Sc Ch 13

27. Section 13-2 Types of Chemical Bonds
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