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The Periodic Table of the Elements

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The periodic table of the elements is a nicely organised collection of data about the types of existing atoms (AKA: elements). More detailed information about the table is found in this entry right after the table itself. Just for a quick start: using the table is really quite simple. To save horizontal space this version of the table is subdivided into three parts: The main group elements, the transition metals and the rare earths. One can use the group, period and atomic numbers to reconstruct the complete table (it should work like a map). The syntax of the table is as follows:

Atomic weight


Symbol


Atomic Number

An asterisk (*) beside the atomic weight indicates that the element is radioactive. The names and the relating symbols are included in a separate table. Further down the entry (after the table part) there are some chapters dedicated to the table itself and to more detailed information about its usage.


The Periodic Table of the Elements


Main Groups
Group
————
Period
12131415161718
11.01
H
1
      4.00
He
2
2 6.94
Li
3
9.01
Be
4
10.81
B
5
12.01
C
6
14.01
N
7
16.00
O
8
19.00
F
9
20.18
Ne
10
322.99
Na
11
24.31
Mg
12
26.98
Al
13
28.09
Si
14
30.97
P
15
32.07
S
16
35.45
Cl
17
39.95
Ar
18
439.10
K
19
40.08
Ca
20
69.72
Ga
31
72.61
Ge
32
74.92
As
33
78.96
Se
34
79.90
Br
35
83.80
Kr
36
585.47
Rb
37
87.62
Sr
38
114.8
In
49
118.7
Sn
50
121.8
Sb
51
127.6
Te
52
126.9
I
53
131.3
Xe
54
6132.9
Cs
55
137.3
Ba
56
204.4
Tl
81
207.2
Pb
82
209.0
Bi
83
209*
Po
84
210*
At
85
222*
Rn
86
7223*
Fr
87
226*
Ra
88
      


Transition Metals
Group
————
Period
3456789101112
444.96
Sc
21
47.88
Ti
22
50.94
V
23
52.00
Cr
24
54.94
Mn
25
55.85
Fe
26
58.93
Co
27
58.69
Ni
28
63.55
Cu
29
65.39
Zn
30
588.91
Y
39
91.22
Zr
40
92.91
Nb
41
95.94
Mo
42
97.9*
Tc
43
101.1
Ru
44
103.0
Rh
45
106.4
Pd
46
107.9
Ag
47
112.4
Cd
48
6138.9
La
57
178.5
Hf
72
180.9
Ta
73
183.8
W
74
186.2
Re
75
190.2
Os
76
192.2
Ir
77
195.1
Pt
78
197.0
Au
79
200.6
Hg
80
7227*
Ac
89
261*
Rf
104
262*
Db
105
263*
Sg
106
262*
Bh
107
-
Hs
108
-
Mt
109
-
Uun
110
-
Uuu
111
-
Uub
112


Rare Earths
Lanthanoids138.9
La
57
140.1
Ce
58
140.9
Pr
59
144.2
Nd
60
145*
Pm
61
150.4
Sm
62
152.0
Eu
63
157.3
Gd
64
158.9
Tb
65
162.5
Dy
66
164.9
Ho
67
167.3
Er
68
168.9
Tm
69
173.0
Yb
70
175.0
Lu
71
Actinoids227*
Ac
89
232.0
Th
90
231*
Pa
91
238.0
U
92
237*
Np
93
244*
Pu
94
243*
Am
95
247*
Cm
96
247*
Bk
97
251*
Cf
98
252*
Es
99
257*
Fm
100
258*
Md
101
259*
No
102
262*
Lr
103


Element name table


Symbol Name    Symbol Name    Symbol Name    Symbol Name    
HHydrogenHeHeliumLiLithiumBeBeryllium
BBoronCCarbonNNitrogenOOxygen
FFluorineNeNeonNaSodiumMgMagnesium
AlAluminiumSiSiliconPPhosphorusSSulphur
ClChlorineArArgonKPotassiumCaCalcium
ScScandiumTiTitaniumVVanadiumCrChromium
MnManganeseFeIronCoCobaltNiNickel
CuCopperZnZincGaGalliumGeGermanium
AsArsenicSeSeleniumBrBromineKrKrypton
RbRubidiumSrStrontiumYYttriumZrZirconium
NbNiobiumMoMolybdenumTcTechnetiumRuRuthenium
RhRhodiumPdPalladiumAgSilverCdCadmium
InIndiumSnTinSbAntimonyTeTellurium
IIodineXeXenonCsCaesiumBaBarium
LaLanthanum            CeCerium              PrPraseodymium         NdNeodymium           
PmPromethiumSmSamariumEuEuropiumGdGadolinium
TbTerbiumDyDysprosiumHoHolmiumErErbium
TmThuliumYbYtterbiumLuLutetiumHfHafnium
TaTantalumW TungstenReRheniumOsOsmium
IrIridiumPtPlatinumAuGoldHgMercury
TlThalliumPbLeadBiBismuthPoPolonium
AtAstatineRnRadonFrFranciumRaRadium
AcActiniumThThoriumPaProtactiniumU Uranium
NpNeptuniumPuPlutoniumAmAmericiumCmCurium
BkBerkeliumCfCaliforniumEsEinsteiniumFmFermium
MdMendeleviumNoNobeliumLrLawrenciumRfRutherfordium
DbDubniumSgSeaborgiumBhBohriumHsHassium
MtMeitneriumUunUnuniliumUuuUnununiumUubUnunbium


More Detailed Information

The periodic table of the elements is a work of generations of scientists (see: History of the Periodic Table), it is not complete1 and it is not in its final layout2. The artificial elements with the atomic number above 105 only exist as traces, they are so instable that only few atoms of these elements have ever been synthesized. The more 'stable' part of the periodic table is widely used in research labs all over the world.

Other Properties of the Elements

Few elements are non-metals. They are: Hydrogen (H), the entire group 18 ('Noble Gases'), Group 17 excluding At, Group 16 excluding Po and Te, Group 15 N and P, As is a semi-metal, Group 14 C, Si is a semi-metal and from Group 13 only B.

Few elements are gaseous at normal conditions (298 K, 1 atm): H (H2), N (N2),O (O2),F (F2),Cl (Cl2) and the Noble Gases. Only two elements are liquid at normal conditions: Hg and Br.

All elements have a variety of different isotopes which are elements with the same nuclear charge but a different amount of neutrons. The properties of different isotopes of the same element vary only very slightly from a chemical point of view. Elements that only have one natural isotope are: Be, F, Na, Al, P, Sc, Mn, Co, As, Y, Nb, Rh, I, Cs, Pr, Pm, Tb, Ho, Tm, Au and Bi.

The measurement unit of the atomic weight is the amu (atomic mass unit). 1 amu corresponds to 1/12 the mass of the 12C isotope (it is sort of an average between the mass of protons and neutrons).

How to Use the Periodic Table of Elements

The table is most commonly used to look up the atomic weight of the elements. Those are used to calculate the molar mass of any compound. The molar mass of a compound is the mass in grammes of 6.022 x 1023 units of the compound (normally molecules). The number 6.022 x 1023 is also called one mole or the Avogadro3 number or more rarely the Lochschmidt number4.

Example: (To illustrate the usage of moles, atomic weights and the periodic table.) For any reason a chemist needs one mole of potassium permanganate (KMnO4). She looks at the formula and calculates the weight of one mole of potassium (by checking the periodic table), one mole of manganese and four moles of oxygen (four because there are four oxygens in one unit of the permanganate). She adds the numbers and finds that she will need 158.04 grammes of the potassium permanganate (which is available as a violet, rather dangerous powder). Weighing a powder is more effective and can be done faster than counting all 6.022 x 1023 molecules5

The second most common use of the periodic table is as laboratory-deco. The periodic table is often found impressed on mouse-pads, t-shirts and posters (in all kinds of design ranging from serious to colourful). Something must be wrong if a chemistry office or lab is not decorated with a periodic table somewhere.

Other usages of the periodic table require some experience in chemistry. The periodic table is organised in a more complex way than it appears on first sight. The elements are not just ordered according to their atomic number (or weight). The position of an element in the table will tell the scientist something about its chemistry. This is so, because the elements are also arranged according to their electronic configuration. (See also: electronic configuration)

How to Use the Periodic Table of the Elements (Advanced)

There are two fundamental trends that go along with the electronic configuration, and the position of the element in the table.

The electronegativity6 increases from left to right in the periodic table, and decreases with the period (excluding the noble gases: they do not have an electronegativity).
The atomic radius decreases with the group number (from left to right), and increases with the period (top-down).

These properties allow an evaluation of the shape and consistency of the electron shells of a certain element. From this, it is possible to estimate the acidity of the hydrides, the solubility of certain compounds in water, the reactivity with other compounds.

Example: What can be predicted for NaBr (sodium bromide) just from the periodic table? Sodium is not very electronegative (it is on the very left side of the table), it will lose his electron for any species which desires to own it more dearly (i.e. for anything with a higher electronegativity), like the bromine atom (on the right side of the table). The sodium loses one electron and will become positively charged, and the bromine atom receives a negative charge. Charged elements (also called ions) are known to be well soluble in water.7 Remark: This explanation is descriptive, it helps to get the picture. One must bear in mind, though, that the real processes taking place in a solution are overwhelmingly more complex and exhaustingly difficult to explain.

Other stuff worth knowing

Group-names

As mentioned before, the periodic table is a collection of element-data arranged according to their weight, and to some of their properties. From this arrangement, the groups have received names which are still in use today. The most well known group-name is probably the halogens (or rather unadorned: Group 17). Before starting with more detailed information on each group, let there be the remark that hydrogen is a big exception, it doesn't fit into any group. And here are the group-names:

Alkali metals - Group 1 (excluding hydrogen): The reaction of these elements with water result in an alkaline solution, hence the name of the group.
Alkaline-earth metals - Group 2: The reaction with water will also lead to an alkaline solution. The addition of 'earth' to the denomination of this group is due to the findings of minerals containing these elements in earth.
Triels - Group 13 (or 'boron-group'): This is a synthetic name originating from the time when group 13 was known as group 3 (tri from the greek version of 'three', and els being a new short form for 'element')
Tetrels - Group 14 (or 'carbon-group'): Same thing happened here. (From tetra which is greek for 'four')
Pentels - Group 15 (or 'nitrogen-group'):Same thing with penta (greek; meaning 'five')
Chalcogens - Group 16: Elements of this group form ores. (chalcos is greek for 'ore' and gennan means 'to form', 'to generate' - like in 'genesis')
Halogens - Group 17: Elements of this group form salts. (halos the greek word for 'salt' and gennan 'to generate')
Noble Gases - Group 18 (or 'inert gases'): Elements of this group do not react. And 'noble' sounds better than 'snob'.

Links. The periodic table of the elements in the net.

Webelements.com (very graphic)
IUPAC Homepage (very official)
The Pictorial Periodic Table (very complete)
1There is no reason to believe it will ever be complete.2The systematics of the periodic table have changed quite often. The official numbering of the groups and periods and the naming of the new discovered or synthesized elements is done by the International Union of Pure and Applied Chemistry (IUPAC).3Amadeo Avogadro (1776-1856), Italian scientist.4Lochschmidt was the first to determine the value of Avogadro's number.5On this level it is of course impossible, and luckily irrelevant, to tell if there are exactly one mole or a few billions or trillions of molecules more or less.6The electronegativity is a very fuzzily defined measure for the affinity of one atom to incorporate one extra electron into its outer electron-shell (this is something like an orbit around the atom's nucleus). This affinity is due to the fact, that certain shell configurations are very stable (eg 8 electrons in one shell). Likewise, there is something like an electropositivity, which would be the proneness of one element to lose one electron for the sake of having a complete outer shell. (Latter measure is not in use since its definition is even fuzzier). For a more precise explanation see: electronic configuration 7NaBr dissolves well in water, if a silver nitrate (AgNO3) solution is added, eventually the Ag and Br ions will come close enough and temporarily built the AgBr compound (silver bromide). This compound is not well soluble in water, it will precipitate. Why? The bromine atom is not electronegative enough to completely retain the electron from the silver (it is also on the right side of the table), both atoms will have to share it, they will not form ions which are easily dissolved in water.

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