1. Atomic Structure Current Atomic model
Dense nucleus contains the mass and positive charge.
The electrons are far outside the nucleus. (e- cloud)

2. The Atomic Scale
Most of the mass of the atom is in the nucleus (protons and neutrons)
Electrons are found outside of the nucleus (the electron cloud)
Most of the volume of the atom is empty space
“q” is a particle called a “quark”

3. About Quarks…(particles that make up protons and neutrons)
Protons and neutrons are NOT fundamental particles.
Protons are made of two “up” quarks and one “down” quark.
Neutrons are made of one “up” quark and two “down” quarks.
Quarks are held together
by “gluons”

4. Subatomic particle symbols
Proton p+
Neutron n0
Electron e-

5. Atomic Particles Summary
Subatomic Particle
Charge
Mass (kg)
Location
Proton, p+ +1
1.673 x 10-27
Nucleus
Neutron, n0
1.675 x 10-27
Electron, e- -1
9.109 x 10-31
Electron cloud
(Very far outside the nucleus)

6. Comparing relative mass:
Subatomic Particle
Charge
Mass (kg)
Location
Proton, p+ +1
1.673 x 10-27
Nucleus
Neutron, n0
1.675 x 10-27
Electron, e- -1
9.109 x 10-31
Electron cloud
(Very far outside the nucleus) 1 1 1
1840 =
Neutron
Proton
1.675 x kg
1.673 x kg
 1 =
Neutron
Electron
1.675 x kg
9.109 x kg
1838.8 1 =
Proton
Electron
1836.6 1
&

7. (Very far outside the nucleus)
Atomic Particles
Subatomic Particle
Charge
Mass (amu)
Location
Proton, p+ +1 1
Nucleus
Neutron, n0
Electron, e- -1
1840
Electron cloud
(Very far outside the nucleus)
Note: atomic mass unit (amu)
1 amu = 1/12 the mass of a carbon-12 isotope.

8. Atomic Number
Atomic number (Z) of an element is the number of protons in the nucleus of each atom of that element.
Atomic # C
Carbon 6
12.011 P
Phosphorus 15
30.97 Au
Gold 79
196.97
Periodic Table
Atomic mass
(average)
Element
# of protons
Atomic # (Z)
Carbon 6
Phosphorus 15
Gold 79

9. Mass Number Nuclide p+ n0 e- Mass #
Mass number is the number of protons and neutrons in the nucleus of an isotope.
Mass # = p+ + n0
Nuclide p+ n0 e-
Mass #
Oxygen - 10 - 33 42
- 31 15 18 8 8 18
Arsenic 75 33 75
Phosphorus 16 15 31
Periodic Table of Elements

10. Isotopes
Isotopes are atoms of the same element having different masses due to varying numbers of neutrons.
Isotope
Protons
Electrons
Neutrons
Nucleus
Hydrogen–1
(protium) 1
Hydrogen-2
(deuterium)
Hydrogen-3
(tritium) 2

11. Chemical Symbol Notation
Zinc-64
Specific Isotope mass
(A) = Mass #
(p+ + n0) 64 2+
Charge on ion Zn
Oxidation state: (Lost 2 e-)
LEO
(Z) =Atomic #
(p+) 30
Chemical Symbol
(Zinc)
30 proton
+ 34 neutrons
64 (mass #)

12. H Hydrogen-1 (Protium) Isotope symbols Chemical Symbol (Hydrogen) 1
Mass #
(p+ + n0) H
1 proton
+ 0 neutrons 1
Atomic #
(p+) 1

13. H Hydrogen-2 (Deuterium) Isotope symbols Chemical Symbol (Hydrogen) 2
Mass #
(p+ + n0) H
1 proton
+ 1 neutrons 2
Atomic #
(p+) 1

14. H Hydrogen-3 (Tritium) Isotope symbols Chemical Symbol (Hydrogen) 3
Mass #
(p+ + n0) H
1 proton
+ 2 neutrons 3
Atomic #
(p+) 1

15. H H H Isotope symbols Hydrogen-1 Hydrogen-2 Hydrogen-3 (Protium)
(Deuterium)
Hydrogen-3
(Tritium) 1 3 2 H H H 1 1 1
1 proton
+ 0 neutrons 1
1 proton
+ 1 neutrons 2
1 proton
+ 2 neutrons 3
Isotopes only differ by number of neutrons.

16. Calculating Average Mass
Atomic mass is the average of all the naturally isotopes of that element.
Copper = amu
Isotope
Symbol
Composition of the nucleus
Mass in
(amu)
Relative Abundance
(% in nature)
Copper-63 63 29
29 protons
34 neutrons
62.93
69.2 %
Copper-65 65
36 neutrons
64.93
30.8 % Cu Cu x
Mass (amu)
Relative abundance
(% as a decimal)
Copper-63
62.93 amu x
0.692
= amu +
Copper-65
64.93 amu x
0.308
= amu
amu
Periodic Table of Elements

17. Atomic Particles 1+ Nucleus e- n0 Note: atomic mass unit (amu)
Subatomic Particle
Symbol
Charge
Location
Relative Mass (amu)
Proton p+
Electron 1-
Neutron
Nucleus
1 amu 1+
Nucleus 1
Very far
outside nucleus 1 e-
1840 n0
Note: atomic mass unit (amu)
1 amu = 1/12 the mass of a carbon-12 isotope.

18. C N Cl Your Turn 7 7- 14 7 7- 15 17 17- 35 17 17- 37 6C N Cl Atomic #
Isotope
Symbol
Atomic #
neutrons
electrons
Mass Number
(p+ + n0)
Isotope Mass in (amu)
Relative abundance
Carbon-12 6C 6
= 6
6 -
6 + 6 = 12
12.000
98.89%
Carbon-13
13 – 6 = 7
6 + 7 = 13
13.003
1.11%
Nitrogen-14 N
14.003
99.63%
Nitrogen-15
15.000
0.37%
Chlorine-35 Cl
34.969
75.77%
Chlorine-37
36.966
24.23% 12 13 14 7 7- 14
14-7=7 7 15 7 7- 15
15-7=8 7 35 17
17- 35
35-17=18 17 37 17
17- 37
37-17=20 17
Atomic # C
Carbon 6
12.011 N
Nitrogen 7
14.007 Cl
Chlorine 17
35.453
Atomic mass
(average)

19. Your Turn (Calculate Average Mass)
Isotope
Symbol
Atomic #
neutrons
electrons
Mass Number
(p+ + n0)
Isotope Mass in (amu)
Relative abundance
Carbon-12 6C 6
= 6
6 -
6 + 6 = 12
12.000
98.89%
Carbon-13
13 – 6 = 7
6 + 7 = 13
13.003
1.11% 12 13 x
Mass (amu)
Relative abundance
(% as a decimal)
Carbon-12
amu x
0.9889
= amu +
Carbon-13
amu x
0.0111
= amu
amu
12.01 amu
Atomic # C
Carbon 6
12.011
Atomic mass
(average)

20. Your Turn (Calculate Average Mass)
Isotope
Symbol
Atomic #
neutrons
electrons
Mass Number
(p+ + n0)
Isotope Mass in (amu)
Relative abundance
Nitrogen-14 N
14.003
99.63%
Nitrogen-15
15.000
0.37%
Chlorine-35 Cl
34.969
75.77%
Chlorine-37
36.966
24.23% 14 7 7- 14
14-7=7 7 15 7 7- 15
15-7=8 7 35 17
17- 35
35-17=18 17 37 17
17- 37
37-17=20 17 x
Mass (amu)
Relative abundance
(% as a decimal)
Nitrogen-14
amu x
0.9963
= amu +
Nitrogen-15
amu x
0.0037
= amu
amu N
Nitrogen 7
14.007
amu

21. Your Turn (Calculate Average Mass)
Isotope
Symbol
Atomic #
neutrons
electrons
Mass Number
(p+ + n0)
Isotope Mass in (amu)
Relative abundance
Nitrogen-14 N
14.003
99.63%
Nitrogen-15
15.000
0.37%
Chlorine-35 Cl
34.969
75.77%
Chlorine-37
36.966
24.23% 14 7 7- 14
14-7=7 7 15 7 7- 15
15-7=8 7 35 17
17- 35
35-17=18 17 37 17
17- 37
37-17=20 17 x
Mass (amu)
Relative abundance
(% as a decimal)
Chlorine-35
amu x
0.7577
= amu +
Chlorine-37
amu x
0.2423
= amu
amu Cl
Chlorine 17
35.453
amu

22. F Si Ti Mn 9 10 14 15 47 25 55 Atomic # = p+ = e- (neutral atom)
Mass # = p+ + n0
Atomic
number
Mass
Number of
protons p+
neutrons n0
electrons e-
Symbol of
element 9 10 14 15 47 25 55 19 9 9 F 14 Si 14 29 22 22
- 25 22 Ti 25 = 30 25 Mn
Atomic # F
Fluorine 9
18.998 Si
Silicon 14
28.086 Ti
Titanium 22
47.867 Mn
Manganese 25
54.938
Atomic mass
(average)

23. Pb Calculate Average Mass Mass # = p+ + n0 1.37 100 + 204 206 207 208
Lead 82
207.20
Calculate Average Mass
Mass # = p+ + n0
82p
122n
82p
124n
82p
125n
82p
126n
% abundance:
1.37%
26.26%
20.82%
51.55%
Mass #
204
206
207
208
1.37
100
No amu mass shown.
Use mass # instead. x
Mass (amu)
Relative abundance
(% as a decimal)
Lead-204
204 x
0.0137 =
Lead-206
206 x
0.2626 =
Lead-207
207 x
0.2082 = +
Lead-208
208 x
0.5155 =
207.21