1. Isotopes & Ions

2. Atomic number = Number of protons
Each atomic number is specific to a certain element
No two different elements have the same atomic number or number of protons
Periodic table is set up in order of increasing atomic number

3. Practice Questions How many protons are in oxygen?8
Potassium (K) has how many protons? 19
Which has more protons, Lithium (Li) or Sodium (Na)? Na

4. If you are talking about a particular element, the number of protons will never change even if the charge changes.
If this is the case, what must change in order for the charge to change?
Number of electrons

5. If atom is neutral, # protons = # electrons
How many electrons are in a neutral atom of Carbon? 6
If an atom is neutral and contains 1 proton, what element is it?
Hydrogen (H)
How many electrons are in a neutral atom of Zinc? 30

6. All atoms of an element are not necessarily identical
They have same physical and chemical properties
can have different numbers of neutrons
This causes atoms to have different masses
Atoms of the same element with different masses are called isotopes.

7. Isotopes Always have the same number of protons
Have same atomic number
Different numbers of neutrons
Different masses (mass numbers)
mass of atom = number protons + number of neutrons
Isotope symbol

8. What do you know about this isotope?

9. Ions Charged element Positive ions: # protons > # electrons
Negative ions: # protons < # electrons

10. Another Isotope symbol
C - 13 Symbol – mass number