1. Calculating PEN (protons, electrons, neutrons) for Atoms and Ions

2. Using your Periodic Table
rounded
Not rounded

3. For a neutral atom… P= atomic number E= atomic number
N= Mass # - Atomic #

4. What are ions? An atom is neutral. It has neither a positive nor a
negative charge. In order for an atom to be neutral,
the number of electrons must equal the number of
protons. The positive and negative charges cancel
each other. If an atom does not have the same
number of protons and electrons, an ion is formed.
When an atom loses or gains one or more electrons,
it acquires a net electrical charge and it is called an
ion.

5. EXAMPLE Number of protons = 12 - Number of electrons = 10 +2
Let’s look at magnesium (Mg)  
To find net charge of an ion, subtract the number of
electrons from the number of protons.
Number of protons = 12
Number of electrons =
A magnesium ion is represented as Mg+2.

6. Charges of Ions by Group

7. Gaining vs. Losing Electrons are NEGATIVELY charged
Gain electrons = negative charge on ion
Lose electrons = positive charge on ion

8. Calculating Electrons in Ions
If the charge is +, you will subtract
If the charge is -, you will add
Ex) Al +³ Atomic # is 13, so originally 13 electrons. But, lost 3 electrons because it is positive. SO, 13-3 = 10 electrons!

9. Complete Nuclear Symbols
Complete nuclear symbol mass number
for an element is Cl +2  element symbol and charge
written like this atomic number
If it is a neutral atom, there is no charge!

10. Isotope Notation If it is a neutral atom, there is no charge!
Element name
Isotope notation is written Carbon-14
like this NEW rounded atomic mass (you use this to calculate neutrons for isotopes)
If it is a neutral atom, there is no charge!