1. What happens if we don’t have the same number of p+ and e-?
Then we no longer have a neutral atom.
Neutral atoms have NO CHARGE

2. What happens if we don’t have the same number of p+ and e-?
They have the same number of positive particles as negative particles. (these cancel each other out!)
Example:
Oxygen has an atomic number of 8.
An atom of oxygen has 8p+ and 8e-
So… = 0

3. What happens if we don’t have the same number of p+ and e-?
In order for an atom to not be neutral, the number of e- changes, the numbers of p+ and n0 remain the same. We call this an ION
Ion- an atom with either a positive or negative charge, a charged particle.

4. Example: Oxygen commonly has a -2 charge.
Oxygen always has 8 p+ (atomic number)
+8 + -x = -2
X = 10
This means there are 10 electrons in an ion of oxygen.
Symbol= O2- or O-2

5. Example: Boron commonly has a +3 charge.
Boron always has 5 p+ (atomic number)
+5 + -x = +3
X = 2
This means there are 2 electrons in an ion of boron.
Symbol: B3+ or B+3

6. Example If an atom has 7 protons and 10 electrons, what is its charge?-3

7. Terms Negative ions are called ANIONS
Means you gain electrons
Positive ions are called CATIONS.
Means you lose electrons

8. Homework Part 7 Pick up bingo sheet and review
Number 3: use ISOTOPE NOTATION (see part 6 for example)
Number 4: Be careful; these are ions, so #p+ doesn’t equal # e-! If the charge is -, there should be more e- than p+!
Number 5: Answers should look like those in number 4
Pick up bingo sheet and review
Bingo sheet must be filled in for tomorrow!
Review and definitions for bingo due WEDNESDAY