1. Protons & Neutrons

2. Proton review In nucleus +1 charge
One proton balances out the charge of one electron
Proton has much greater mass than an electron
Ignore mass of electron in determining mass of an atom

3. 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

4. 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

5. 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

6. If you know the atom of an element is neutral and you know either the number of protons or the atomic number, you can always determine the number of electrons in that atom
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

7. Neutrons review Part of nucleus Neutral charge (0 charge)
Mass = 1 amu (same as mass of proton)
Knowing this, what part of the atom has the majority of the mass?
Nucleus (electrons are in electron cloud and do not influence the mass of the atom)

8. All atoms of an element are not necessarily identical
They have same characteristics and chemical properties (have the same atomic number/number of protons)
Atoms can have different numbers of neutrons in the nucleus
This causes atoms to have different masses
Atoms of the same element with different masses are called isotopes.

9. 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

10. What do you know about this isotope?