The first peroidic table appeared in 1869 and is credited to a Russian chemist, Dimitri Mendeleev, although another was created at about the same time by Julius Meyer, a German physicist. The Mendeleev table is the basis of the one used today, and is largely unchanged.
HISTORY
Mendeleev arranged the elements according to his periodic law, which states
"The properties of the elements are a peroidic function of their atomic mass"
When he arranged the elements like this, he found certain elements grouped themselves into vertical families, what are now known as groups . The horizontal rows formed are known as periods. Perhaps the most important observation was the relationship between atomic weights and proprties of the elements, and the trend of elements in each group to have consistantly high or low values of certain properties.
Dimitri Mendeleev created this, the original, periodic table. |
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Reihen |
Gruppe I. - R2O |
Gruppe II. - RO |
Gruppe III. - R2O3 |
Gruppe IV. RH4 RO2 |
Gruppe V. RH3 R2O5 |
Gruppe VI. RH2 RO3 |
Gruppe VII. RH R2O7 |
Gruppe VIII. - RO4 |
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1 | H = 1 | |||||||||||||||||
2 | Li = 7 |
Be = 9,4 |
B = 11 |
C = 12 |
N = 14 |
O = 16 |
F = 19 |
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3 | Na = 23 | Mg = 24 | Al = 27,3 | Si = 28 | P = 31 | S = 32 | Cl = 35,5 | |||||||||||
4 | K = 39 | Ca = 40 | - = 44 | Ti = 48 | V = 51 | Cr = 52 | Mn = 55 | Fe = 56, Co=59 Ni=59, Cu=63 |
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5 | (Cu = 63) | Zn = 65 | - = 68 | - = 72 | As = 75 | Se = 78 | Br = 80 | |||||||||||
6 | Rb = 85 | Sr = 87 | ?Yt = 88 | Zr = 90 | Nb = 94 | Mo = 96 | - = 100 | Ru=104, Rh=104 Pd=106, Ag=108 |
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7 | Ag = 108 | Cd = 112 | In = 113 | Sn = 118 | Sb = 122 | Te = 125 | J = 127 | |||||||||||
8 | Cs = 133 | Ba = 137 | ?Di = 138 | ?Ce = 140 | - | - | - | - - - - | ||||||||||
9 | (-) | - | - | - | - | - | - | |||||||||||
10 | - | - | ?Er = 178 | ?La = 180 | Ta = 182 | W = 184 | - | Os=195, Ir=197, Pt=198, Au=199 |
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11 | (Au = 199) | Hg = 200 | Tl = 204 | Pb = 207 | Bi = 208 | - | - | |||||||||||
12 | - | - | - | Th = 231 | - | U = 240 | - | - - - - |
There were inconsistancies in this first table, but these were rectified by Professor Mosley, a British physicist who modified the table by arranging the elements by atomic number, not atomic mass. Mosley's periodic law, based on atomic number is now regarded as correct.
Group | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1A | 2A | 3B | 4B | 5B | 6B | 7B | 8B | 1B | 2B | 3A | 4A | 5A | 6A | 7A | 8A | ||||
Period | |||||||||||||||||||
1 | 1 H |
2 He | |||||||||||||||||
2 | 3 Li |
4 Be |
5 B |
6 C |
7 N |
8 O |
9 F |
10 Ne | |||||||||||
3 | 11 Na |
12 Mg |
13 Al |
14 Si |
15 P |
16 S |
17 Cl |
18 Ar | |||||||||||
4 | 19 K |
20 Ca |
21 Sc |
22 Ti |
23 V |
24 Cr |
25 Mn |
26 Fe |
27 Co |
28 Ni |
29 Cu |
30 Zn |
31 Ga |
32 Ge |
33 As |
34 Se |
35 Br |
36 Kr | |
5 | 37 Rb |
38 Sr |
39 Y |
40 Zr |
41 Nb |
42 Mo |
43 Tc |
44 Ru |
45 Rh |
46 Pd |
47 Ag |
48 Cd |
49 In |
50 Sn |
51 Sb |
52 Te |
53 I |
54 Xe | |
6 | 55 Cs |
56 Ba |
* | 71 Lu |
72 Hf |
73 Ta |
74 W |
75 Re |
76 Os |
77 Ir |
78 Pt |
79 Au |
80 Hg |
81 Tl |
82 Pb |
83 Bi |
84 Po |
85 At |
86 Rn |
7 | 87 Fr |
88 Ra |
** | 103 Lr |
104 Rf |
105 Db |
106 Sg |
107 Bh |
108 Hs |
109 Mt |
110 Uun |
111 Uuu |
112 Uub |
113 Uut |
114 Uuq |
115 Uup |
116 Uuh |
117 Uus |
118 Uuo |
lanthanides | * | 57 La |
58 Ce |
59 Pr |
60 Nd |
61 Pm |
62 Sm |
63 Eu |
64 Gd |
65 Tb |
66 Dy |
67 Ho |
68 Er |
69 Tm |
70 Yb |
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actinides | ** | 89 Ac |
90 Th |
91 Pa |
92 U |
93 Np |
94 Pu |
95 Am |
96 Cm |
97 Bk |
98 Cf |
99 Es |
100 Fm |
101 Md |
102 No |
Each of the vertical groups of the table are given a number, and this corresponds to the number of valence electrons each element in that group has. Each period is numbered according to how many occupied energy shells the elements in it have, so, although the elements considered on this page are known as the first row elements, they actually fall in period 2, hydrogen and helium being the only element in period 1.
Group 1 elements - Known as the alkali metals, these elements are unusually soft and highly reactive with water and oxygen.
Although Mendeleev's table is by far the most practical and widely used, there has been some other tables made, for instance
Stowe's physicists periodic table (1988),
Benfey's periodic spiral (1960) and
Zmaczynski's periodic triangle (1935).
To demonstrate the trends that do exist between elements, and to illustrate just how good the periodic table is at representing this, i have choosen the first row elements as they simply show the patterns which can be found throughout the periodic table.
This section is divided into information on the individual elements and periodic trends.
ARRANGEMENT
Group 2 elements - Known as the alkali earth metals, but are not as soft or reactive as the Group 1 metals.
Group 3 to 12 elements - These are the transition metals, and do not have such uniform properties due to shielding effects on the inner electrons.
Group 13 to 18 elements - Known as the representative elements.
Group 17 - The halogens, which means "salt makers".
Group 18 - The noble gases. There are very few componds of these elements as they are so unreactive, with no desire to gain or lose electrons.
FIRST ROW ELEMENTS
INDIVIDUAL ELEMENTS
Li Be B C N O F Ne
CLICK ON AN ELEMENT FOR FUTHER INFORMATION
PERIODIC TRENDS
Covalent radius | Electronegativity | Effective nuclear charge | Ionisation energy | Atomic weight |
Page written by Keira Stobie 01/05/97
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