1. Chapter 6 Chemical Bonds
Warm-up Question:
1. What are valence electrons?
2. List the number of valence electrons for the following elements:
Na ________K ________ Cl __________Al _________
***Hint: You need your periodic table***

2. C6H12O6 Chemical Bonds… Chemical bonding forms COMPOUNDS
Chemical Bond – force that holds atoms together
Bonding occurs between the valence electrons
These chemical bonds are constantly being made and broken down in our environment.
Your body breaks the chemical bonds in the food we eat to get energy so our body can do work.
Chemical bonding forms COMPOUNDS
Reading a Chemical compound formula
C6H12O6

3. Chemical Bonds… (cont)
There are two types of chemical bonds.
The difference is what they do with their valence electrons.
1. Ionic Bonds - One atom steals electrons from another atom.
Ionic is always a metal with a nonmetal
2. Covalent Bonds – Electrons are shared between the atoms.
Covalent is always two nonmetals

4. Representing Valence Electrons
Lewis Dot Structure – model of an atom in which each dot represents a valence electron
* symbol in the center is the nucleus and all the inner electrons in the atom
C =
S =
He =

5. IONIC COMPOUNDS Ion - an atom that has a charge. (+ or -)
2 types of ions
1. anion – negatively charged ion (must gain electrons) ex: Cl-1 O-2 N-3
2. cation - positively charged ion (must lose electrons) ex: Ca+2 K+1 Al+3
***You can determine charge by where they are located on the periodic table.

6. Stable Electron Configurations
When the highest energy level is filled with electrons, the atom is stable and not likely to react.
Octet Rule – the tendency of atoms to gain or lose electrons in order to fill the outer most electron shell.(a full outer shell has 8 valence electrons)
What group on the periodic table already has a full outer most shell?

7. Drawing Lewis Dot Structures of Ions
Cations – they are + charge so they must have ________ electrons.
Examples:
Anions – They are – charge so they must have _______ electrons.

8. Dot Structures for Ionic Compounds
Examples:
BaO
CaCl2
Mg3 N2
AlBr3
*** Now for the homework assignment***

9. → Na+Cl- → Mg+2S-2 II. Ionic Bonds
1. ion – an atom that has a positive or negative charge
a. When an atom gains or loses an electron, the # of protons no longer = the # of electrons
b. 2 types of ions
1. anion – negatively charged ion (gains a electron)
2. cation - positively charged ion (loses a electron)
→ Na+Cl-
→ Mg+2S-2

10. 2. Ionic Bond – Form between metals and nonmetal (transfer of electrons) ex. NaCl, MgO, CaBr2
3. Chemical Bond – force that holds atoms together
4. Ionization energy – amount of energy used to remove an electron
a. Lower the ionization energy, the easier it is to remove an electron from an atom
b. Ionization energies increase from left to right in a period
Ex. More energy is required to remove an electron from a nonmetal than a metal.
c. Energy increases from the bottom of a group to the top
Ex. Easier to remove an electron from K than Na

11. III. Covalent Bonds – form between two non-
III. Covalent Bonds – form between two non- metals (sharing of electrons)
a. Molecule – neutral group of atoms that are joined together by one or more covalent bonds
IV. Metallic bonds
1. Metal in a sea of electrons
Ex. Cu, Al, Fe

12. V. Unequal Sharing of Electrons
1. Electronegativity – ability of an atom attract electrons to itself, greater this number the greater its ability to attract electrons
a. Non-Polar Covalent Bonding- an equal sharing of electrons
ex. F2
b. Polar Covalent Bonding - an unequal sharing of electrons
ex. HF
attraction between polar molecules are stronger

13. VI. Naming Compounds and Writing Formulas
a. The subscripts on H2 = 2 atoms in 1 molecule of hydrogen
b. determining the number of atoms
Ex. P2F4 =
2 phosphorus atoms
4 fluorine atoms
Ex. (NaSO4)3 =
3 sodium
3 sulfate
12 oxygen

14. = CaCl2 Sodium Chloride Boron Phosphide
1. Writing Formulas for ionic compounds
a. list the symbols and charges for the cation and anion
b. use the criss cross method
ex.
2. Naming Ionic Compounds (TYPE 1)
A. Cations (metals) and Anion (nonmetal)
1st cation before the anion (or metal before the nonmetal)
2nd drop the end of the second element and add “ide”
Ex. NaCl =
BP =
= CaCl2
Sodium Chloride
Boron Phosphide

15. 3. Naming TYPE (2)
A. If the metal is a transition metal Roman Numerals in parentheses are used
1 = (I)
2 = (II)
3 = (III)
4 = (IV)
5 = (V)
ex. Cu+2 = copper (II) ion
Fe+3 = iron (III) ion
CuCl2 =
Iron (III) oxide =
Copper (II) Chloride
Fe2O3

16. DiNitrogen Monoxide P2F4 3. Naming Covalent Compounds (TYPE 3)
A. Name between two nonmetals
1st – most metallic element first (element farthest to the left)
2nd – then add “ide” on the end of the second element
3rd – then add a prefix (mono is never used with the 1st element)
Ex. N2O =
Ex. diphosphorus tetraflouride =
DiNitrogen Monoxide
P2F4