1. Chemical Bonding
Mr. Fleming

2. Content Standards
9.4 D.11
Describe how atoms combine to form new substances by transferring electrons (ionic bonding) or sharing electrons (covalent bonding).

3. Significance of Chemical Bonding
Changes chemical properties of matter
Mechanism to build more complex matter
Determines how energy is transferred in a system
Energy released= Exothermic
Energy absorbed= Endothermic
Vital Chemical Reactions
Cellular Respiration= how are cells produce energy
Combustion=how we drive from point A to point B

4. Essential Questions What are ionic and covalent bonds?
Why do bonds occur?
How do you predict what type of bond atoms will form?

5. What is Bonding?
Bonds between atoms are caused by electrons in outermost shells or valence electrons.
The process of bond formation is called a chemical reaction
Lewis-Dot Diagrams illustrate the bonding electrons within the elements doing the bonding.

7. The Rules of Bonding Octet Rule Electronegitivity
Elements want to fill outer shell with 8 electrons with exception of Helium and Hydrogen which want 2.
Electronegitivity
Elements ability to capture electrons
Increases as you go to top right of periodic table. (See Next Slide)

9. Electronegitivity of Periodic Table

10. Types of Bonds Ionic Covalent Transfer of electrons
Electrons are not shared
Na+ Cl-
Covalent
Sharing electrons
Chlorine Gas (Cl2)
Hydrogen and nonmetal like Chlorine.

11. The Ionic Bond

12. Sodium 23 Na 11
e.c. 2,8,1
11p
12n
11 protons
12 neutrons
11 electrons

13. Lewis Dot Diagram: Sodium

14. Chlorine Cl e.c. 2,8,7 17 protons 18 Neutrons 17 electrons 35 17 17p

15. Lewis Dot Diagram: Sodium

16. + The Sodium atom has 1 Electron in it’s outer shell.Na
e.c. 2,8,1
Atom +
The Sodium loses 1 electron to leave a complete outer shell.
It is now a Sodium ion with a charge of 1 +
(Na +)
e.c. (2,8)+
Ion

17. - The Chlorine atom has 7 electrons in it’s outer shell.Cl
e.c. 2,8,7
Atom -
(Cl - )
The Chlorine gains 1 electron to gain a complete outer shell.
It is now a Chlorine ion with a charge of 1 -
e.c. (2,8,8)-
Ion

18. + - The Ionic Bond Sodium atom Na Chlorine atom Cl Sodium ion (Na +)
Chlorine ion
(Cl -)
The sodium atom loses one electron to attain a complete outer shell and become a positive ion (Na +). The Chlorine atom gains one electron to attain a complete outer shell and become a negative ion (Cl –). Strong electrostatic forces attract the sodium and chlorine ions.

19. Lewis Dot Diagram: Na Cl

20. Ionic Compounds
Held together by strong electrostatic forces
Opposite charges attract
High melting points and boiling points
Regular structures – giant ionic lattices
When melted or dissolved ionic compounds conduct electricity

21. Examples of Ionic Compounds
Metal + Nonmetal
LiF - Lithium Fluoride
LiCl - Lithium Chloride
NaF - Sodium Fluoride
NaCl - Sodium Chloride
KBr - Potassium Bromide
KI - Potassium Iodide
CsF - Cesium Fluoride
CsCl - Cesium Chloride

22. Lewis Dot Diagram: Cl2

23. Chlorine atom 2,8,7

24. 2 Chlorine atoms
Outer shells only

25. Molecular or covalent compounds are usually gases or liquids – they have low melting points and low boiling points
Chlorine molecule Cl2
Electrons shared
Each outer shell has 8 electrons
Forces (bonds) between atoms in the molecule very strong
Forces between molecules very weak
Molecules have no overall electric charge

26. Covalent Bonds:
Water H2O
Methane CH4
Ammonia NH3
Hydrogen H2
Hydrogen Chloride HCl
Oxygen O2
N.B. Oxygen has a double bond

27. Oxygen O 16 8
Oxygen atom 2,6

28. 2 Oxygen atoms (outer shells only)
Double covalent bond O

29. Chemical Bonding Recall
1. In a chemical bond, __________ are being shared amongst different elements.
Electrons
2. A _______ bond is when electrons are not being shared.
Ionic

30. Chemical Bonding Recall
3. Will Lithium (Li) and Chlorine (Cl) form an ionic or covalent bond? Ionic Bond 4. Draw the resulting Lewis Dot structure that forms when lithium and chlorine bond.