1. Atom Notes

2. All matter that exists is made up of atoms.
These atoms are made up of other parts, called; protons, electrons, and neutrons.
Let’s look at each of these individually.

3. The Nucleus
The central part of any atom is called the nucleus of the atom.
The nucleus of an atom contains 2 types of particles.
They are the protons and the neutrons

4. Protons
Protons are located in the nucleus of atoms and each proton has a positive (+) electrical charge
It’s the number of protons in an atom that determine what the atom is and also determines that atom’s atomic number.

5. Protons continued
For example, hydrogen has 1 proton, thus has an atomic number of 1
Uranium has 92 protons, and thus has an atomic number of 92.

6. Neutrons Neutrons are also located in the nucleus of atoms.
A neutron and a proton have pretty much the same mass , but they don’t have the same electrical properties

7. Neutrons continued
Protons have a positive electrical charge, but neutrons don’t have any charge at all, so we say they are electrically neutral

8. Atomic Mass
The atomic mass of an atom is determined by adding the number of protons and neutrons together.
Sodium, for example, has an atomic mass of 23 and an atomic number of 11, so how many neutrons does it have?

9. Example #1
Nitrogen (N) has an atomic number of 7 and an atomic mass of 14.
How many protons does N have?
How many neutrons does N have?

10. Example #2
Gold (Au) has an atomic number of 79 and an atomic mass of 197.
How many protons does Au have?
How many neutrons does Au have?

11. Electrons
Electrons are located outside, around the nucleus of an atom.
An appropriate analogy for this would be how the blades of a fan can move very, very fast, and pretty much fill up an entire space around the fan blades, even though they really are not that large

12. Electrons continued
In many atoms the number of protons and electrons is the same number. So if an atom has 13 protons, it would also have 13 electrons.
If an atom has an atomic number of 22, then it would have 22 protons and also 22 electrons.
What element would that be?

13. Electrons continued
The electrons are in motion (orbit) around the nucleus of atoms (at nearly the speed of light) in a certain order.
They are located in what are called energy levels.
The electrons fill the energy levels in a certain way.

14. Electrons continued again!
The 1st energy level is the smallest and can hold up to 2 electrons.
Once the 1st energy level is filled with 2 electrons, then the 2nd energy level can start being filled with electrons.
The 2nd energy level can hold up to 8 electrons.
Once the 2nd energy level is filled, then the 3rd energy level can start taking electrons.
(up to 18 in the 3rd energy level)

15. Sodium (Na) How many electrons does sodium have?
How many electrons in sodium’s first energy level?
2nd energy level?
3rd energy level?

16. Hydrogen How many electrons does H have?
How many electrons does H have in it’s 1st energy level?
Why doesn’t H have more than one energy level?

17. Neon (Ne) How many electrons does Ne have?
How many electrons does Ne have in it’s 1st energy level?
2nd?
3rd?
Why does Ne Not have a 3rd energy level?

18. 3 types of chemical bonds
Ionic bond-holds crystals together, involves an exchange of electrons
Metallic bond-hold atoms of a metal together
Covalent bond-holds molecules together, involves a sharing of electrons

19. Valence electrons
The electrons in an atom’s outermost shell are the valence electrons
These electrons are the ones that determine what an atom will bond with

20. Electron dot diagrams
Electron dot diagrams immediately show you 2 things-
How many valence electrons an atom has
How many of the valence electrons are paired.

21. Example of electron dot diagram for Cl
7 valence electrons shown
1 unpaired electron.

22. Kr electron dot diagram
8 valence electrons
No unpaired electrons
Kr is a nobel (inert) gas

23. A plethora of Electron dot diagrams

24. What is a “polar molecule”
One side of a water molecules gets more face time with the electrons than the other side.

25. Water polarity
Oxygen, being a larger molecule than hydrogen, get more face time with the electrons,
A water molecule becomes polarized, that is, it has a net + and – side.

26. Snowflake humor