John D. Reid

Research Interests
Sub-Atomic Structure
According to the Standard Model all matter consists of quarks and leptons. The chemical periodic table of elements, shown below in figure 1, lists the atoms found in nature. Atoms consist of protons, neutrons and electrons. The protons and neutrons are contained in the nucleus of the atom. The electrons are outside the nucleus.

Electrons are the lightest of the leptons. Protons and neutrons are made up of the lightest quarks,(the up quark, u, and the down quark, d). Matter containing heavier quarks and leptons is rare, but can be found in nature in such places as cosmic rays and is also produced in particle accelerators.

One way to model the structure of the atom is to think of it as a little solar system with the electrons orbiting the nucleus. This is called the Bohr model, and, as with most models, has it's limitations. The Bohr model does a good job of describing such things as atomic spectra (the way light is emitted from an atom) but it does not describe some other aspects very well. For example, if the electron were moving like a planet around a sun it would radiate energy away quickly and spiral into the nucleus. Thus atoms in general, would not be stable entities. A better description of the atom takes into account the wave properties of matter. This page uses the Bohr model.

Figure 2 shows the atom's structure using the Bohr model. The figure shows how the electrons (leptons) and quarks are arranged. The figure is not to scale. For example, if the nucleus were one millimeter in diameter, the electrons would be about 100 feet away. Also, quarks and leptons are currently thought to be point particles. That is, as far as experiments can determine, they have no size! Thus this figure merely represents the arrangement of the particles and not their size.

Fig 1. Periodic Table of Elements
Each element is an atom. The number below each element gives the number of neutrons, protons and electrons. For example, Li - lithium, has 3 neutrons, 3 protons, and 3 electrons.
1a2a3b4b5b6b7b 8 1b2b3a4a5a6a7a 0
H
1 		He
2
Li
3 		Be
4 		B
5 		C
6 		N
7 		O
8 		F
9 		Ne
10
Na
11 		Mg
12 		Al
13 		Si
14 		P
15 		S
16 		Cl
17 		Ar
18
K
19 		Ca
20 		Sc
21 		Ti
22 		V
23 		Cr
24 		Mn
25 		Fe
26 		Co
27 		Ni
28 		Cu
29 		Zn
30 		Ga
31 		Ge
32 		As
33 		Se
34		 Br
35 		Kr
36
Rb
37 		Sr
38 		Y
39 		Zr
40 		Nb
41 		Mo
42 		Tc
43 		Ru
44 		Rh
45 		Pd
46 		Ag
47 		Cd
48 		In
49 		Sn
50 		Sb
51 		Te
52 		I
53 		Xe
54
Cs
55 		Ba
56 		La
57 		Hf
72 		Ta
73 		W
74 		Re
75 		Os
76 		Ir
77 		Pt
78 		Au
79 		Hg
80 		Tl
81 		Pb
82 		Bi
83 		Po
84 		At
85 		Rn">Rn
86
Fr
87 		Ra
88 		Ac
89 		Rf
104 		Ha
105 		??
106
Lanthinide
Series		 Ce
58 		Pr
59 		Nd
60 		Pm
61 		Sm
62 		Eu
63 		Gd
64 		Tb
65 		Dy">Dy
66 		Ho
67 		Er
68 		Tm
69 		Yb
70 		Lu
71
Actinide
Series		 Th
90 		Pa
91 		U
92 		Np
93 		Pu
94 		Am
95 		Cm
96 		Bk
97 		Cf
98 		Es
99 		Fm
100 		Md
101 		No
102 		Lr
103

Fig 2. Sub-Atomic Structure

BACK TO John Reid's Research Page
(http://www.lhup.edu/jreid/research.htm)
BACK TO John Reid's Home Page
(http://www.lhup.edu/jreid/home.htm)