1. Chemical Bonding
Chapter 11

2. 11.1: Electrons and Energy Levels
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. 11.1: Electrons and Energy Levels
Combining Atoms Through Chemical Bonding
Chemical Bond - is the joining of atoms to form ionic compounds or molecules
The properties of these new substances are different than the properties of the original substance.
When chemical bonds form, electrons are
Lost
Gained
shared

4. 11.1: Electrons and Energy Levels
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. 11.1: Electrons and Energy Levels

6. 11.1: Electrons and Energy Levels
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.

7. 11.1: Electrons and Energy Levels
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.

8. 11.1: Electrons and Energy Levels
Showing valence electrons used in bonding
Electron Dot Diagrams
models that represent valence electrons in an atom as dots around the element’s chemical symbol
Steps
Identify the element’s group number on the periodic table
Identify the number of valence electrons
Draw the electrons as dots (NESWNESW)
Determine if stable or how many bonds can form
Stable: All electrons are paired
Bonds possible: Each unpaired set of electrons

9. Draw electron dot diagrams for the valence electrons!
Stable elements?
1 bond possible?
2 bonds possible?
3 bonds possible?
4 bonds possible?

10. 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?

11. 11.2: Compounds, Chemical Formulas, and Covalent Bonds
Covalent Bonds are formed when two nonmetals share electrons.
Covalent Bond – a bond that forms when atoms share one or more pairs of electrons

12. 11.2: Compounds, Chemical Formulas, and Covalent Bonds
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.

13. 11.2: Compounds, Chemical Formulas, and Covalent Bonds
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

14. 11.2: Compounds, Chemical Formulas, and Covalent Bonds
1. Draw an electron dot diagram for each element
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

15. 11.2: Compounds, Chemical Formulas, and Covalent Bonds
Draw the Lewis Structures (electron dot diagrams) for each of the following
CH CO2

16. 11.2: Compounds, Chemical Formulas, and Covalent Bonds
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

17. 11.3: Ionic and Metallic Bonds
Ionic Compounds
Examples of ionic compounds:
1. table salt
2. deicer
Properties
1.high melting points
2. high boiling points
Substances containing ionic bonds consist of individual particles called formula units.
Formula unit - a neutral group of atoms that are joined together by an ionic bond

18. 11.3: Ionic and Metallic Bonds
An ionic bond is an attraction between positively and negatively charged ions in an ionic compound
Electrons are transferred
This creates ions, which are atoms that are no longer electrically neutral because they have gained or lost valence electrons
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

19. 11.3: Ionic and Metallic Bonds
Charged Particles
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 (electrons) and positive charges (protons) no longer cancel out and the atom becomes an ion.
Ion- an atom that gained or lost electrons

20. 11.3: Ionic and Metallic 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

21. 11.3: Ionic and Metallic Bonds
Charged Particles Continued
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 = __________

22. 11.3: Ionic and Metallic Bonds
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 IONIC CHARGES

23. 11.3: Ionic and Metallic Bonds
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.

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

25. 11.3: Ionic and Metallic Bonds
Ionic Bonding Pictures
Draw the electron dot diagram for each element
Show the transfer of electrons from the metal to the nonmetal
Add more metal or nonmetal atoms until all elements have a full octet
Sodium Chlorine
Magnesium Fluorine

26. 11.3: Ionic and Metallic Bonds
Ionic Bonding Pictures
Lithium oxygen
Aluminum sulfur

27. 11.3: Ionic and Metallic Bonds
Writing Formulas for Ionic Compounds ( metal + nonmetal)
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

28. 11.3: Ionic and Metallic Bonds
Write the formula for the ionic compound that forms:
1. Potassium + Sulfur
2. Magnesium + nitrogen
3. Aluminum + phosphorous

29. 11.3: Ionic and Metallic Bonds
Naming Ionic Compounds
Name of Metal + nonmetal w/ ending –ide
Examples:
Sodium and Chlorine
Barium and Fluorine
Potassium and Oxygen
Lithium and Sulfur

30. 11.3: Ionic and Metallic Bonds
When ions bond, they form a repeating 3-dimensional pattern called a crystal lattice.

31. 11.3: Ionic and Metallic Bonds
Properties of Metals
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

32. 11.3: Ionic and 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.
Sea of electrons or pool of electrons.

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