1. Chemical Bonding
Chapter 11

2. Electrons and Chemical Bonding
Have you ever stopped to consider that by using the 26 letters of the alphabet, you make all of the words you use every day? Although the number of letters is limited, you combine them in different ways to make a huge number of words. This is the same with elements. We combine them to make different substances.

3. Combining Atoms Through Chemical Bonding
Chemical Bond - is the joining of atoms to form new substances
The properties of these new substances are different than the properties of the original substance.
When chemical bonds form, electrons are lost, gained, or shared

4. Electron Number and Organization
To understand how atoms form chemical bonds, you need to understand how electrons are arranged in an atom.
The number of electrons in an atom = the number of protons.
The number of protons can be determined by the atomic number.
The electrons are organized in energy levels.
1st Energy Level: Diagram Fluorine:
2nd Energy Level: 8
3rd Energy Level: 8

5. Outer-Level Electrons and Bonding
Not all electrons in an atom take part in a bonding.
Most bonds form using the outer most electrons called valence electrons.
Valence electron - an electron in the outermost energy level of an atom.

6. To bond or Not to Bond Not all atoms bond the same way.
The number of valence electrons determines if an atom will form a bond.
Atoms want to be like noble gases (have a full outer shell of electrons).
8 valence electrons
2 valence electrons like He
Atoms bond by gaining, losing, or sharing electrons to have a full outer most energy level like the noble gases.

7. Complete with your partner
1. How many valence electrons does C have?
2. How many valence electrons does Ca have?
3. How many valence electrons does S have?
4. Why do elements form bonds?

8. Covalent Compounds
Covalent Bonds are formed when two nonmetals share electrons.
Covalent Bond – a bond that forms when atoms share one or more pairs of electrons

9. Covalent Compounds Examples of covalent compounds: 1. ammonia 2. water
3. carbon dioxide
Properties
1.low melting points
2. low boiling points
3. Brittle as a solid
Substances containing covalent bonds consist of individual particles called molecules.
molecule - a neutral group of atoms that are joined together by one or more covalent bonds.

10. Covalent Compounds Simple Covalent Compounds
When found in nature as pure elements, these seven elements exist only as two atoms covalently bonded. H2 O2 N2
Cl2
Br2 I2 F2 7 N 8 O 9 F 19 Cl 35 Br 53 I 1 H

11. Covalent Compounds
How to draw covalent molecules: using electron dot diagrams
Write the symbol of the element and place one dot around the symbol for every valence electron in the atom.
Examples:
Carbon Oxygen
Krypton Hydrogen

12. Covalent Compounds
2. Combine the elements where they can share electrons so each have a full outer shell. (The shared electrons are the covalent bond)
Examples:
Hydrogen + Chlorine
Fluorine + Fluorine
Water
Oxygen + Oxygen

13. Complete with your partner
Draw the Lewis Structures for each of the following
CH CO2

14. Covalent Compounds One = mono Two = di Three = tri Four = tetra
Naming Covalent Compounds
Prefixes
One = mono
Two = di
Three = tri
Four = tetra
Five = penta
Six = hexa
Seven = hepta
Eight= octa
Nine = nona
Ten = deca
Rules:
Prefix + name Prefix + name –ide
Rule: Do NOT use mono- on the first element
Examples: CO
CO2
C2H4
P2O5
N3P6

15. Ionic Bonds
Ionic Bonds-are formed when electrons are transfered from one atom to another.
Ionic bonds form so that the outermost energy levels of the atoms in the bonds are full.
Ionic bonds form between a metal and a nonmetal
Sodium Chlorine

16. Ionic Bonds Charged Particles (Magnets)
A transfer of electrons between atoms changes the number of electrons in each atom but the number of protons stay the same.
The negative charges and positive charges no longer cancel out and the atom becomes an ion.
Ion- an atom that gained or lost electrons

17. Ionic Bonds Charged Particles Continued
An atom cannot lose electrons without a nearby atom gaining electrons and visa versa.
Metals – tend to lose electrons and become a positive ion (cation)
Nonmetals – tend to gain electrons and become a negative ion (anion)
-ide- the ending that is given to atoms that gain electrons
Oxygen = __________
Fluorine = __________
Sulfur = __________

18. Ionic Compounds
Metals tend to lose a certain number of electrons depending on their number of valence electrons and become positively charged
Nonmetals tend to gain a certain number of electrons depending on their number of valence electrons and become negatively charged

19. Ionic Compounds
When ionic bonds form, the number of electrons lost by the metal equals the number of electrons gain by the nonmetal atoms.
The ions that bond are charged but the compounds formed are neutral because the charges on the ions cancel out.

20. Complete with your partner
What types of elements form Ionic compounds?
Why?

21. Ionic Compounds Writing Ionic Compounds ( metal + nonmetal) Examples:
Write the metal with its’ charge
Write the nonmetal with its’ charge
Criss- Cross the charges
Only bring down the #, NOT the charge
Examples:
Sodium and Chlorine
Barium and Chlorine
Potassium and Oxygen
Lithium and Sulfur

22. Complete with your partner
Write the formula for the ionic compound that forms:
1. Potassium + Sulfur
2. Magnesium + nitrogen
3. Aluminum + phosphorous

23. Ionic Compounds Naming Ionic Compounds Examples:
Name of Metal + nonmetal w/ ending –ide
Examples:
Sodium and Chlorine
Barium and Fluorine
Potassium and Oxygen
Lithium and Sulfur

24. Ionic Compounds
When ions bond, they form a repeating 3-dimensional pattern called a crystal lattice.

25. Metallic Bonds Properties of Metals 2. ductile
1. malleable
2. ductile
3. conduct heat/electric well
Metals are malleable and ductile because of the presence of a metallic bonds.
Metallic Bond – a bond between metals of the same atom

26. Metallic Bonds
The positive ions in a metal form a lattice that is held in place by strong interactions between the positive ions and the surrounding electrons.
Swimming in electrons.

27. Complete on your own
Write a paragraph about the 3 types of bonds and the types of elements that are involved in each.