1. A. Chemical Compound: two or more atoms chemically combined.
II. Compounds & Bonding
A. Chemical Compound: two or more atoms chemically combined.
1. Expressed as a 3-part molecular formula:
Symbol
Coefficient
Subscript
Example:
To calculate the total numbers of individual atoms, multiply the coefficient by the subscripts.
In the molecules above, we have 6 hydrogen atoms and 3 oxygen atoms.

2. 2. More Examples: find the total number of each atom in the molecules below.
a. 2 Glucose molecules: 2C6H12O6 C: H: O: 12 24
b. 6 Methanes: 6CH4 C: H: 6 24

3. c. 1 Ammonium Phosphate: (NH4)3PO412 1 4
When a group of elements are inside of parentheses with a subscript outside, multiple the subscript outside by the subscript of each element to calculate total number of each atom (distributive property)
d. 2 Iron Sulfates: 2Fe2(SO4) 3
Fe: S: O: 4 6 24

4. B. Chemical Bonds
There are 2 main types of chemical bonds that hold molecules together
(Chemical bonds require and store energy)
1. Covalent Bond: atoms share their valence (outer-most) electrons.
*The number of valence electrons determines how many bonds an atom can make.
*Atoms “want” to fill their valence shells.
Structural Formula
Example 1: H2O (water)

5. H O H O H O H
Represents 1 pair of shared electrons
Structural Formula

6. Example 2: CH4 (methane)
*Draw the bonded Bohr Diagram, Lewis Structure, and Structural Formula of methane.

7. electrons are transferred from one atom to another, creating ions.
2. Ionic Bond:
electrons are transferred from one atom to another, creating ions.
a. Ion: an atom that has lost or gained electrons thus having a positive or negative charge.
Lost e- = positive ion
Gained e- = negative ion

8. Opposites attract, BABY!
b. The opposite charges between ions create a strong attraction in ionic bonding.
Hey! Could you spare an electron?
Example: NaCl (table salt)
Thanks!
You sure you don’t mind? I didn’t want to be a bother!
Sorry – I can’t help it!
You sure it’s ok?
I suddenly find myself attracted to you!
Sure – I have one extra!
Don’t be so negative! Cl Na
I’m positive!
Me too! I feel like we’re bonding! - +
Opposites attract, BABY!

9. Neutral Sodium Atom:
Protons: +11
Electron: -11
Charge: 0
Neutral Chlorine Atom:
Protons: +17
Electron: -17
Charge: 0
Sodium Ion:
Protons: +11
Electron: -10
Charge: +1
Chlorine Ion:
Protons: +17
Electron: -18
Charge: -1

10. Put brackets around the atom that received the electron(s)._ Cl Cl Na + Na
Put brackets around the atom that received the electron(s).

11. Hey! Those are mine! Now I’m going to keep an ion both of you!+2
Give me an electron!
Me too! Cl Cl - -

12. Mg Cl Cl

13. weak attraction between polar molecules that are very close together
C. Hydrogen Bonds:
1. Polar Molecules form when electrons are not shared equally between atoms in a molecule, so poles (opposite charges) form at either end of the molecule.
2. The positive pole of one molecule is attracted to the negative pole of another.

14. D. Writing chemical equations:
Products
Reactants
Yields
6CO2 +
6H2O
C6H12O6 +
6O2
6 Carbon
12 Hydrogen
6 Carbon
6 Oxygen
12 Oxygen
12 Oxygen
6 Oxygen
12 Hydrogen
18 Oxygen total
18 Oxygen total
*Whatever goes into the reaction (reactants) must come out (products).
 You will have the same number of atoms on either side of the equation!

15. _____ H2 + _____ O2  _____H2O4 H O 2 1 4 2