Modern Periodic Table

The periodic table , also known as the periodic table of the elements, arranges the chemical elements into rows ("periods")and columns ("groups"). It is an icon of chemistry and is widely used in physics and other sciences. It is a depiction of the periodic law, which says that when the elements are arranged in order of their atomic numbers an approximate recurrence of their properties is evident. The table is divided into four roughly rectangular areas called blocks. Elements in the same group tend to show similar chemical characteristics.

Vertical, horizontal and diagonal trends characterize the periodic table. Metallic character increases going down a group and decreases from left to right across a period. Nonmetallic character increases going from the bottom left of the periodic table to the top right.

The first periodic table to become generally accepted was that of the Russian chemist Dmitri Mendeleev in 1869; he formulated the periodic law as a dependence of chemical properties on atomic mass. As not all elements were then known, there were gaps in his periodic table, and Mendeleev successfully used the periodic law to predict some properties of some of the missing elements. The periodic law was recognized as a fundamental discovery in the late 19th century. It was explained early in the 20th century, with the discovery of atomic numbers and associated pioneering work in quantum mechanics both ideas serving to illuminate the internal structure of the atom. A recognizably modern form of the table was reached in 1945 with Glenn T. Seaborg's discovery that the actinides were in fact f-block rather than d-block elements. The periodic table and law are now a central and indispensable part of modern chemistry.

The periodic table continues to evolve with the progress of science. In nature, only elements up to atomic number 94 exist; to go further, it was necessary to synthesize new elements in the laboratory. Today, while all the first 118 elements are known, thereby completing the first seven rows of the table, chemical characterization is still needed for the heaviest elements to confirm that their properties match their positions. It is not yet known how far the table will go beyond these seven rows and whether the patterns of the known part of the table will continue into this unknown region. Some scientific discussion also continues regarding whether some elements are correctly positioned in today's table. Many alternative representations of the periodic law exist, and there is some discussion as to whether there is an optimal form of the periodic table.

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IA
IIA
IIIB
IVB
VB
VIB
VIIB
VIIIB
VIIIB
VIIIB
IB
IIB
IIIA
IVA
VA
VIA
VIIA
VIIIA
1 1.008 H Hydrogen
2 4.0026 He Helium
3 6.94 Li Lithium
4 9.0122 Be Beryllium
5 10.81 B Boron
6 12.011 C Carbon
7 14.007 N Nitrogen
8 15.999 O Oxygen
9 18.998 F Fluorine
10 20.180 Ne Neon
11 22.990 Na Sodium
12 24.305 Mg Magnesium
13 26.982 Al Aluminum
14 28.085 Si Silicon
15 30.974 P Phosphorus
16 32.06 S Sulfur
17 35.45 Cl Chlorine
18 39.948 Ar Argon
19 39.098 K Potassium
20 40.078 Ca Calcium
21 44.956 Sc Scandium
22 47.867 Ti Titanium
23 50.942 V Vanadium
24 51.996 Cr Chromium
25 54.938 Mn Manganese
26 55.845 Fe Iron
27 58.933 Co Cobalt
28 58.693 Ni Nickel
29 63.546 Cu Copper
30 65.38 Zn Zinc
31 69.723 Ga Gallium
32 72.630 Ge Germanium
33 74.922 As Arsenic
34 78.971 Se Selenium
35 79.904 Br Bromine
36 83.798 Kr Krypton
37 85.468 Rb Rubidium
38 87.62 Sr Strontium
39 88.906 Y Yttrium
40 91.224 Zr Zirconium
41 92.906 Nb Niobium
42 95.95 Mo Molybdenum
43 (98) Tc Technetium
44 101.07 Ru Ruthenium
45 102.91 Rh Rhodium
46 106.42 Pd Palladium
47 107.87 Ag Silver
48 112.41 Cd Cadmium
49 114.82 In Indium
50 118.71 Sn Tin
51 121.76 Sb Antimony
52 127.60 Te Tellurium
53 126.90 I Iodine
54 131.29 Xe Xenon
55 132.91 Cs Cesium
56 137.33 Ba Barium
72 178.49 Hf Hafnium
73 180.95 Ta Tantalum
74 183.84 W Tungsten
75 186.21 Re Rhenium
76 190.23 Os Osmium
77 192.22 Ir Iridium
78 195.08 Pt Platinum
79 196.97 Au Gold
80 200.59 Hg Mercury
81 204.38 Tl Thallium
82 207.2 Pb Lead
83 208.98 Bi Bismuth
84 (209) Po Polonium
85 (210) At Astatine
86 (222) Rn Radon
87 (223) Fr Francium
88 (226) Ra Radium
104 (267) Rf Rutherfordium
105 (268) Db Dubnium
106 (271) Sg Seaborgium
107 (272) Bh Bohrium
108 (277) Hs Hassium
109 (278) Mt Meitnerium
110 (281) Ds Darmstadtium
111 (282) Rg Roentgenium
112 (285) Cn Copernicium
113 (286) Nh Nihonium
114 (289) Fl Flerovium
115 (290) Mc Moscovium
116 (293) Lv Livermorium
117 (294) Ts Tennessine
118 (294) Og Oganesson
57 138.91 La Lanthanum
58 140.12 Ce Cerium
59 140.91 Pr Praseodymium
60 144.24 Nd Neodymium
61 (145) Pm Promethium
62 150.36 Sm Samarium
63 151.96 Eu Europium
64 157.25 Gd Gadolinium
65 158.93 Tb Terbium
66 162.50 Dy Dysprosium
67 164.93 Ho Holmium
68 167.26 Er Erbium
69 168.93 Tm Thulium
70 173.05 Yb Ytterbium
71 174.97 Lu Lutetium
89 227 Ac Actinium
90 232.04 Th Thorium
91 231.04 Pa Protactinium
92 238.03 U Uranium
93 (237) Np Neptunium
94 (244) Pu Plutonium
95 (243) Am Americium
96 (247) Cm Curium
97 (247) Bk Berkelium
98 (251) Cf Californium
99 (252) Es Einsteinium
100 (257) Fm Fermium
101 (258) Md Mendelevium
102 (259) No Nobelium
103 (262) Lr Lawrencium

Sub-category

Alkali Metals
Alkali Earth Metals
Transition Metals
Post-Transition Metals
Metalloids
Reactive Non-Metals
Noble Gas
Lanthanides
Actinides
Unknown Properties
1 1.008 H Hydrogen
Atomic Number
Atomic Weight
Symbol
Name

State Of Matter [Text-Color]

Solid
Liquid
Gas

Each chemical element has a unique atomic number (Z) representing the number of proton its nucleus. Most elements have multiple isotopes, variants with the same number of protons but different numbers of neutrons. For example, carbon has three naturally occurring isotopes: all of its atoms have six protons and most have six neutrons as well, but about one per cent have seven neutrons, and a very small fraction have eight neutrons. Isotopes are never separated in the periodic table; they are always grouped together under a single element. When atomic mass is shown, it is usually the weighted average of naturally occurring isotopes; but if there are none, the mass of the most stable isotope usually appears, often in parentheses.

In the standard periodic table, the elements are listed in order of increasing atomic number Z. A new row (period) is started when a new electron shell has its first electron. Columns (groups) are determined by the electron configuration of the atom; elements with the same number of electrons in a particular sub-shell fall into the same columns (e.g. oxygen, sulfur, and selenium are in the same column because they all have four electrons in the outermost p-sub-shell). Elements with similar chemical properties generally fall into the same group in the periodic table, although in the f-block, and to some respect in the d-block, the elements in the same period tend to have similar properties, as well. Thus, it is relatively easy to predict the chemical properties of an element if one knows the properties of the elements around it.

The first 94 elements occur naturally; the remaining 24, americium to oganesson (95-118), occur only when synthesized in laboratories. Of the 94 naturally occurring elements, 83 are primordial and 11 occur only in decay chains of primordial elements. A few of the latter are so rare that they were not discovered in nature, but were synthesized in the laboratory before it was determined that they do exist in nature after all: technetium (element 43), promethium (element 61), astatine (element 85), neptunium (element 93), and plutonium (element 94).[6] No element heavier than einsteinium (element 99) has ever been observed in macroscopic quantities in its pure form, nor has astatine; francium (element 87) has been only photographed in the form of light emitted from microscopic quantities (300,000 atoms).