1. The Parts of the Atom

2. MATTER = ATOM All matter is composed of atoms.
Atoms are the smallest part of an element that keeps that element’s properties.
If an atom were the size of a football field, the nucleus would be the size of a marble and nearly all of the mass of the atom is in the nucleus.
The space around the nucleus and the electron have very, very little mass. This means that matter is mostly empty!

3. The nucleus contains most of the mass of the atom (protons + neutrons)
The nucleus contains most of the mass of the atom (protons + neutrons). The rest is mostly empty space!

4. The difference between protons, neutrons, and electrons is:

5. Sub -Atomic Particles & Charge
Protons have a positive charge. (+1)
Neutrons are electrically neutral. (0)
Electrons have a negative charge. (-1) 5

6. Protons & Neutrons The atomic number equals the number of protons.
The mass number equals the total number of subatomic particles in the nucleus.
(protons and neutrons)

7. Look at the periodic table, and find each of the elements above
Look at the periodic table, and find each of the elements above. Find where they Atomic Number is located on the table.

10. Neutrons The number of neutrons can be calculated.
number of neutrons = mass number – atomic number

11. ISOTOPES of an element - vary in mass because their numbers of neutrons differ.
This is why the atomic weight is not always a whole number
it is an average of the atomic masses for that element

12. The same number of protons but different numbers of neutrons
In a nutshell
The same number of protons
but different numbers of neutrons

13. Protons
The number of protons is what distinguishes the atom from another.
Change the number of protons and you change the element.
Hydrogen – 1
Helium - 2

14. Electrons Most atoms are electrically neutral.
Have the same number of electrons as protons.
Same positives and negatives
= 0,
If the numbers aren’t even the atom is charged and is called an Ion
++ - = +1, = -1

15. Ion Only electrons can be gained or lost!!!!!
Example. Hydrogen, which has an atomic number of 1, usually has 1 proton and 1 electron
A Hydrogen Ion has 1 proton and 2 electrons…therefore it has a charge of -1.
( 1 p= + 1, 2 e= -2….so = -1)
Only electrons can be gained or lost!!!!!

16. Valence Electrons
are the electrons in the outer most shell (don’t count all electrons, only last shell)
Determine the chemical properties of the atom
Each shell can only hold so many e-
When the shell is full it is said to be stable
Shell 1 = 2
Shell 2 = 8
Shell 3 = 8

17. Valence Electrons

18. Goodbye e-, Welcome e- Atoms want their valance shells filled!!
So sometimes an electron might leave or one might be ‘invited in’ to fill or empty a valance shell
This is why Ions exist….if an electron leaves or joins the atom, now the number of protons and electrons is NOT the same, therefore there is a charge!!