1. Models of Matter:
Atomic Structure

2. subatomic electron proton neutron nucleus neutral
OUTCOME QUESTION(S):
S1-2-02:
What is the basic subatomic structure of an atom?
S1-2-04
How do you use atomic mass and atomic number to identify parts of the atom?
Vocabulary & Concepts 
subatomic electron proton
neutron nucleus neutral
Amu (µ) atomic mass atomic number

3. Subatomic – a fundamental particle smaller than an atom.
Experiments proved 3 subatomic particle:
Electron (e-): Small, negative electric charge
Proton (p+): Positive electric charge
Neutron (no): NO charge, same size as protons
Scientists have since found many more fundamental particles – many by crashing particles into each other to see the little pieces in the collision
Subatomic – a fundamental particle smaller than an atom.

4. Electrons occupy the space around the nucleus.
The protons and neutrons are found in the dense centre of the atom – nucleus.
Electrons occupy the space around the nucleus.
Atoms contain an equal number of (+) charged protons and (-) charged electrons.
Overall atom is neutral.

5. The number of protons in an element does NOT change.
Important points:
The number of protons in an element does NOT change.
No TWO elements have the same number of protons.
Atoms can lose and gain neutrons and electrons – since protons have NEVER been shown to change we use this to identify elements

6. Atomic Number
Atomic Mass
This information on the Periodic Table will help us build atomic models of any element

7. Atomic Number
Smaller value – no units
Equals the number of protons in the nucleus
p+ number is used to identify an element
Remember atoms are neutral (equal p+ and e-): Atomic number can be the number of protons OR electrons in the atom

8. How many protons and electrons in Carbon? Copper?
Atomic Number
How many protons and electrons in Carbon?
Copper?
6 protons and 6 electrons
29 protons and 29 electrons

9. Amu is just a unit to measure very small masses equal to
Protons (p+) have mass of 1 Atomic Mass Unit (μ)
Neutrons (no) are the same size - also 1 μ
Electrons (e-) are so small - considered zero mass
So ALL of the mass of an atom comes from the protons and neutrons only.
Amu is just a unit to measure very small masses equal to
x grams +
Protons
Neutrons -
electrons

10. Larger value – total mass in amu (μ) - Round off the value
Atomic Mass
Larger value – total mass in amu (μ)
- Round off the value
Equals total number of p+ and no in the nucleus
Since protons and neutrons each weight 1 amu – for Helium, a mass of 4.00 reveals there must be a total number of 4 subatomic particles in the nucleus

11. Atomic Number Atomic Mass
(Protons/Electrons) (Protons + Neutrons)
PROTONS
Atomic Number = 2
NEUTRONS
A.mass – A.number = 4 – 2 = 2
ELECTRONS
Same as Protons = 2

12. Sulfur (S)
How many protons are there in one atom of Sulfur?
Atomic number p+
How many electrons in one atom of Sulfur?
Atoms are neutral e-
How many neutrons in one atom of Sulfur?
Atomic mass = 16 no
How many protons in 3 atoms of Sulfur?
3 x 16 = 48 p+

13. An atom is found with 19 protons:
What element is this?
Potassium
How many electrons in one atom of Potassium?
Atoms are neutral – 19 e -
How many neutrons in one atom of Potassium?
At mass – At number 39 – 19 = 20 no
How many protons in 10 atoms of Potassium?
10 x 19 p + = 190 p +

14. CAN YOU ANSWER THESE QUESTIONS? S1-2-02:
What is the basic subatomic structure of an atom?
S1-2-04
How do you use atomic mass and atomic number to identify parts of the atom?
Vocabulary & Concepts 
subatomic electron proton
neutron nucleus neutral
Amu (µ) atomic mass atomic number