1. Subatomic Particles (Sections 4.2 and 4.3)
Dr. Walker
Surry County High School

2. What will you learn? The subatomic particles located within an atom
The location, charge, and relative mass of subatomic particles within an atom
How the number of subatomic particles affect the atomic number and mass number of an element
To determine atomic symbols from numbers of subatomic particles

3. Three Subatomic Particles
Proton
Positively Charged
Located in nucleus
Larger than electrons, same size as neutron
Held in nucleus by nuclear force (aka strong force)
Overcomes repulsion of like charged particles

4. Three Subatomic Particles
Neutron
No charge
Located in nucleus
Same size as proton, larger than electrons

5. Three Subatomic Particles
Electron
Negatively charged
Located in electron clouds (shells)
Less massive than protons

6. Compare and Contrast Chart
Subatomic Particle
Mass
Location
Charge
Proton
1.67 x kg
Nucleus +
Neutron
uncharged
Electron
9.1 x kg (much smaller)
Orbitals (outside nucleus) -

7. Sub-Subatomic Particles
Quarks
Located in the nucleus
Six “flavors”
Protons and neutrons made of quarks and have a different composition
New SOL content

8. Atomic Number Atomic numbers are included in the periodic table
For a neutral atom: atomic number = # of protons = # of electrons

9. Periodic Table Entry

10. Mass Number Mass number = protons + neutrons
Electrons are too small to count (1/1000 the size of protons and neutrons)
Mass number is a whole number (not the same as atomic mass)

11. Average Atomic Mass
The average atomic mass for each element is the weighted average of that element’s naturally occurring isotopes
Isotope = same # protons, different # of neutrons
Protons must stay the same, neutrons can change
Mass numbers are whole numbers (can’t have part of a proton or neutron)
Atomic masses are decimals because they are averages!!

12. Learning Check
What is the mass number of an element with 7 protons, 8 neutrons, and 7 electrons?
What is the atomic number of this element?

13. Learning Check
What is the mass number of an element with 7 protons, 8 neutrons, and 7 electrons?
15 (7 protons + 8 neutrons)
What is the atomic number of this element? 7

14. Relating New Terms Protons Electrons Neutrons ______ Located in
_______
Located in ______

15. Relating New Terms Protons Electrons Neutrons Located in nucleus
Mass number
Located in
nucleus
Atomic
number
Located in orbitals
(aka shells)

16. Element
Number of Protons
Number of Neutrons
Number of Electrons
Mass Number
lithium 7
carbon
chlorine 35
silver 61
lead
207
calcium 20
tantalum
181
radium
226
samarium 88
uranium
238
americium
148
lawrencium
268

17. Element
Number of Protons
Number of Neutrons
Number of Electrons
Mass Number
lithium 3 4 7
carbon 6 13
chlorine 17 18 35
silver 47 61
108
lead 82
125
207
calcium 20 40
tantalum 73
181
radium 88
138
226
samarium 62
150
uranium 92
146
238
americium 95
148
243
lawrencium
103
165
268

18. Atomic Symbols 12 6 C 13 14
Top Number = mass number (protons + neutrons)
Bottom Number = atomic number (protons, electrons)

19. Atomic Symbols 12 6 C 13 14
Protons 6
Neutrons 7 8
Electrons
To get neutrons, subtract the bottom number (protons)
from the top (protons + neutrons)

20. Atomic Symbol Practice
Give the number of protons, neutrons, and electrons for the following symbols
3517Cl
8537Rb
7935Br

21. Atomic Symbol Practice
Give the number of protons, neutrons, and electrons for the following symbols
3517Cl
8537Rb
7935Br
17 protons
17 electrons
18 neutrons
37 protons
37 electrons
48 neutrons
35 protons
35 electrons
44 neutrons

22. Atomic Symbol Practice
Give the atomic symbol for:
An atom with 3 protons, 3 electrons, and 4 neutrons
An atom with 15 protons, 15 electrons, and 17 neutrons

23. Atomic Symbol Practice
Give the atomic symbol for:
An atom with 3 protons, 3 electrons, and 4 neutrons
73Li
An atom with 15 protons, 15 electrons, and 17 neutrons
3215P

24. More Practice 8 39 8035Br 45 30 65 Element Atomic Symbol Atomic Number
Mass Number
# of protons
# of neutron
# of electron 8
Potassium 39
8035Br 45 30 65

25. More Practice Oxygen 168O 8 16 3919K 19 39 20 Bromine 8035Br 35 80 45
Element
Symbol
Atomic
Number
Mass Number
# of protons
# of neutron
# of electron
Oxygen
168O 8 16
Potassium
3919K 19 39 20
Bromine
8035Br 35 80 45
Zinc
6530Zn 30

26. Isotopes Same atom, different number of neutrons
All atoms of an element must have the same number of protons
All hydrogens have 1 proton
All heliums have 2 protons, etc., etc.
The neutrons can be different
11H, 21H, 31H
These are called isotopes

27. Average Atomic Mass The weighted average of all isotopes of an element
Average: Add up terms, divide by number of terms
Weighted average: Multiply each term by percentage as decimal, add terms
No division in a weighted average!
Represented by decimal number with each element of the periodic table

28. Average Atomic Mass Example with grades
Johnny has a 90 homework average (20%), 70 quiz average (20%), 60 test average (40%), 60 exam (20%)

29. Average Atomic Mass Example with grades
Johnny has a 90 homework average (20%), 70 quiz average (20%), 60 test average (40%), 60 exam (20%)
Regular average
( )/4 = 280/4 = 70 - C
Weighted average
(90 x 0.2) + (70 x 0.2) + (60 x 0.4) + (60 x 0.2) = 68 - D
homework
quiz
test
exam

30. Average Atomic Mass Chemical example
For the element boron, 10B occurs 19% of the time, while 11B occurs 81% of the time.

31. Average Atomic Mass Chemical example
For the element boron, 10B occurs 19% of the time, while 11B occurs 81% of the time.
Use the mass number and percentages (as decimals)
(10 x 0.19) + (11 x 0.81) = 10.81

32. Review What is the charge of each subatomic particle?
The mass number contains which subatomic particles?
The atomic number is equal to which subatomic particles?
If a fluorine atom has a mass number of 19, how many protons, electrons, and neutrons does it contain?
Give the atomic symbol for an element containing 33 protons, 33 electrons, and 42 neutrons.

33. Terms To Know Skills To Master
Proton
Neutron
Electron
Quark
Isotope
Mass Number
Atomic Number
Average Atomic Mass
Calculating mass number from numbers of protons and neutrons
Calculating protons, neutrons, and electrons from mass number
Recognizing isotopes of the same element

34. Corresponding Text
Subatomic Particles – pp