1. Bellringer Draw a model for the following elements: A. Sodium
B. Chlorine
2. How many valence electrons does sodium have?
3. If sodium lost its valence electrons, what would its charge be?
4. How many valence electrons does chlorine have?
5. If chlorine gained an electron, what would its charge be?

2. Sodium Chlorine 1 A. 1 B. X X X X X X X X X X X X X X X X X X X X X X
P: 11
N: 12 X X X
P: 17
N: 18 X X X X X X X X X X X
One +1
Seven -1

3. I. Bonding Atoms
Atoms bond because their valence electrons interact
Bonding occurs so that atoms will have stable outer energy levels
What is a stable outer energy level? How many electrons?
1st Energy level: 2e-
ii. 2nd, 3rd, 4th, etc…Energy level: 8e-

4. Example: Hydrogen
Valence electrons: 1
Energy levels: 1 X X
The valence electron in each hydrogen is shared, giving each atom a stable outer energy level.

5. II. Ionic Bonds
Ionic Bonds –
Formed between oppositely charged ions
Metals form positive ions
2. Nonmetals form negative ions
B. When one atom loses an electron, another atom gains that same electron
Salt is formed from positively charged sodium ions and negatively charged chlorine ions

6. Chloride Ion (negative)
Example:
Sodium Ion (positive)
Na [Na]+
Cl [ Cl ]-
Chloride Ion (negative)

7. C. The chemical formula, NaCl, tells the ratio of sodium to chloride ions
D. Characteristics of ionic compounds:
Conduct electricity when dissolved
Metallic bonds – the attraction between a nucleus of one atom and the electrons from another atom
Causes atoms to pack close to each other

8. III. Covalent Bonds
Covalent Bond –
Molecules, made when electrons are shared between atoms

9. The line indicates shared electrons
Example: Chlorine
Seven Valence Electrons X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X
The line indicates shared electrons
Cl Cl

10. O O N N Elements can form double or triple bonds
The compounds above share electrons equally, so they form nonpolar covalent bonds
2. Not all covalent bonds are nonpolar
Water is a polar covalent molecule

11. IV. Polyatomic Ions
Polyatomic Ions –
Groups of covalently bonded atoms that have either gained or lost electrons
Polyatomic Ion Examples:
NH4+
ammonium
PO33-
phosphite
NO2-
nitrite
NO3-
nitrate
OH-
hydroxide

12. C. Polyatomic ions usually end in -ate or -ite
B. A polyatomic ion that is bonded with another atom is often indicated with parentheses
(NH4)2SO4
Ammonium sulfate
But not always
NH4NO3
Ammonium nitrate
C. Polyatomic ions usually end in -ate or -ite
-ate indicates one additional oxygen atom than the polyatomic ion with -ite
ClO3-
chlorate
ClO2-
chlorite

13. Quiz: Match the polyatomic ion with its name
____ 1. SO42- B
A. sulfite
____ 2. SO32- A
B. sulfate
_____ 3. AsO43- C
C. arsenate
____ 4. AsO33- D
D. arsenite