Atomic Number 81

  1. The atomic number the the number of protons and therefore the total positive charge in the nucleus. So the the element with the atomic number 82 has more protons and a greater nuclear charge then.
  2. Thallium (Tl) is a soft gray metal that has the atomic number 81 in the periodic table in Group 13. It has the symbol Tl. Thallium was discovered in 1861 by William Crookes he had been given an ore containing selenium which he extracted leaving behind tellurium.

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No.
Atomic
weight
NameSym.M.P.
(°C)
B.P.
(°C)
Density*
(g/cm3)
Earth
crust (%)*
Discovery
(Year)
Group*Electron configurationIonization
energy (eV)
11.008HydrogenH-259-2530.090.14177611s113.60
24.003HeliumHe-272-2690.181895181s224.59
36.941LithiumLi1801,3470.5318171[He] 2s15.39
49.012BerylliumBe1,2782,9701.8517972[He] 2s29.32
510.811BoronB2,3002,5502.34180813[He] 2s2 2p18.30
612.011CarbonC3,5004,8272.260.09ancient14[He] 2s2 2p211.26
714.007NitrogenN-210-1961.25177215[He] 2s2 2p314.53
815.999OxygenO-218-1831.4346.71177416[He] 2s2 2p413.62
918.998FluorineF-220-1881.700.03188617[He] 2s2 2p517.42
1020.180NeonNe-249-2460.90189818[He] 2s2 2p621.56
1122.990SodiumNa988830.972.7518071[Ne] 3s15.14
1224.305MagnesiumMg6391,0901.742.0817552[Ne] 3s27.65
1326.982AluminumAl6602,4672.708.07182513[Ne] 3s2 3p15.99
1428.086SiliconSi1,4102,3552.3327.69182414[Ne] 3s2 3p28.15
1530.974PhosphorusP442801.820.13166915[Ne] 3s2 3p310.49
1632.065SulfurS1134452.070.05ancient16[Ne] 3s2 3p410.36
1735.453ChlorineCl-101-353.210.05177417[Ne] 3s2 3p512.97
1839.948ArgonAr-189-1861.78189418[Ne] 3s2 3p615.76
1939.098PotassiumK647740.862.5818071[Ar] 4s14.34
2040.078CalciumCa8391,4841.553.6518082[Ar] 4s26.11
2144.956ScandiumSc1,5392,8322.9918793[Ar] 3d1 4s26.56
2247.867TitaniumTi1,6603,2874.540.6217914[Ar] 3d2 4s26.83
2350.942VanadiumV1,8903,3806.1118305[Ar] 3d3 4s26.75
2451.996ChromiumCr1,8572,6727.190.0417976[Ar] 3d5 4s16.77
2554.938ManganeseMn1,2451,9627.430.0917747[Ar] 3d5 4s27.43
2655.845IronFe1,5352,7507.875.05ancient8[Ar] 3d6 4s27.90
2758.933CobaltCo1,4952,8708.9017359[Ar] 3d7 4s27.88
2858.693NickelNi1,4532,7328.900.02175110[Ar] 3d8 4s27.64
2963.546CopperCu1,0832,5678.96ancient11[Ar] 3d10 4s17.73
3065.390ZincZn4209077.13ancient12[Ar] 3d10 4s29.39
3169.723GalliumGa302,4035.91187513[Ar] 3d10 4s2 4p16.00
3272.640GermaniumGe9372,8305.32188614[Ar] 3d10 4s2 4p27.90
3374.922ArsenicAs816135.72ancient15[Ar] 3d10 4s2 4p39.79
3478.960SeleniumSe2176854.79181716[Ar] 3d10 4s2 4p49.75
3579.904BromineBr-7593.12182617[Ar] 3d10 4s2 4p511.81
3683.800KryptonKr-157-1533.75189818[Ar] 3d10 4s2 4p614.00
3785.468RubidiumRb396881.6318611[Kr] 5s14.18
3887.620StrontiumSr7691,3842.5417902[Kr] 5s25.69
3988.906YttriumY1,5233,3374.4717943[Kr] 4d1 5s26.22
4091.224ZirconiumZr1,8524,3776.510.0317894[Kr] 4d2 5s26.63
4192.906NiobiumNb2,4684,9278.5718015[Kr] 4d4 5s16.76
4295.940MolybdenumMo2,6174,61210.2217816[Kr] 4d5 5s17.09
43*98.000TechnetiumTc2,2004,87711.5019377[Kr] 4d5 5s27.28
44101.070RutheniumRu2,2503,90012.3718448[Kr] 4d7 5s17.36
45102.906RhodiumRh1,9663,72712.4118039[Kr] 4d8 5s17.46
46106.420PalladiumPd1,5522,92712.02180310[Kr] 4d108.34
47107.868SilverAg9622,21210.50ancient11[Kr] 4d10 5s17.58
48112.411CadmiumCd3217658.65181712[Kr] 4d10 5s28.99
49114.818IndiumIn1572,0007.31186313[Kr] 4d10 5s2 5p15.79
50118.710TinSn2322,2707.31ancient14[Kr] 4d10 5s2 5p27.34
51121.760AntimonySb6301,7506.68ancient15[Kr] 4d10 5s2 5p38.61
52127.600TelluriumTe4499906.24178316[Kr] 4d10 5s2 5p49.01
53126.905IodineI1141844.93181117[Kr] 4d10 5s2 5p510.45
54131.293XenonXe-112-1085.90189818[Kr] 4d10 5s2 5p612.13
55132.906CesiumCs296781.8718601[Xe] 6s13.89
56137.327BariumBa7251,1403.590.0518082[Xe] 6s25.21
57138.906LanthanumLa9203,4696.1518393[Xe] 5d1 6s25.58
58140.116CeriumCe7953,2576.771803101[Xe] 4f1 5d1 6s25.54
59140.908PraseodymiumPr9353,1276.771885101[Xe] 4f3 6s25.47
60144.240NeodymiumNd1,0103,1277.011885101[Xe] 4f4 6s25.53
61*145.000PromethiumPm1,1003,0007.301945101[Xe] 4f5 6s25.58
62150.360SamariumSm1,0721,9007.521879101[Xe] 4f6 6s25.64
63151.964EuropiumEu8221,5975.241901101[Xe] 4f7 6s25.67
64157.250GadoliniumGd1,3113,2337.901880101[Xe] 4f7 5d1 6s26.15
65158.925TerbiumTb1,3603,0418.231843101[Xe] 4f9 6s25.86
66162.500DysprosiumDy1,4122,5628.551886101[Xe] 4f10 6s25.94
67164.930HolmiumHo1,4702,7208.801867101[Xe] 4f11 6s26.02
68167.259ErbiumEr1,5222,5109.071842101[Xe] 4f12 6s26.11
69168.934ThuliumTm1,5451,7279.321879101[Xe] 4f13 6s26.18
70173.040YtterbiumYb8241,4666.901878101[Xe] 4f14 6s26.25
71174.967LutetiumLu1,6563,3159.841907101[Xe] 4f14 5d1 6s25.43
72178.490HafniumHf2,1505,40013.3119234[Xe] 4f14 5d2 6s26.83
73180.948TantalumTa2,9965,42516.6518025[Xe] 4f14 5d3 6s27.55
74183.840TungstenW3,4105,66019.3517836[Xe] 4f14 5d4 6s27.86
75186.207RheniumRe3,1805,62721.0419257[Xe] 4f14 5d5 6s27.83
76190.230OsmiumOs3,0455,02722.6018038[Xe] 4f14 5d6 6s28.44
77192.217IridiumIr2,4104,52722.4018039[Xe] 4f14 5d7 6s28.97
78195.078PlatinumPt1,7723,82721.45173510[Xe] 4f14 5d9 6s18.96
79196.967GoldAu1,0642,80719.32ancient11[Xe] 4f14 5d10 6s19.23
80200.590MercuryHg-3935713.55ancient12[Xe] 4f14 5d10 6s210.44
81204.383ThalliumTl3031,45711.85186113[Xe] 4f14 5d10 6s2 6p16.11
82207.200LeadPb3271,74011.35ancient14[Xe] 4f14 5d10 6s2 6p27.42
83208.980BismuthBi2711,5609.75ancient15[Xe] 4f14 5d10 6s2 6p37.29
84*209.000PoloniumPo2549629.30189816[Xe] 4f14 5d10 6s2 6p48.42
85*210.000AstatineAt3023370.00194017[Xe] 4f14 5d10 6s2 6p59.30
86*222.000RadonRn-71-629.73190018[Xe] 4f14 5d10 6s2 6p610.75
87*223.000FranciumFr276770.0019391[Rn] 7s14.07
88*226.000RadiumRa7001,7375.5018982[Rn] 7s25.28
89*227.000ActiniumAc1,0503,20010.0718993[Rn] 6d1 7s25.17
90232.038ThoriumTh1,7504,79011.721829102[Rn] 6d2 7s26.31
91231.036ProtactiniumPa1,568015.401913102[Rn] 5f2 6d1 7s25.89
92238.029UraniumU1,1323,81818.951789102[Rn] 5f3 6d1 7s26.19
93*237.000NeptuniumNp6403,90220.201940102[Rn] 5f4 6d1 7s26.27
94*244.000PlutoniumPu6403,23519.841940102[Rn] 5f6 7s26.03
95*243.000AmericiumAm9942,60713.671944102[Rn] 5f7 7s25.97
96*247.000CuriumCm1,340013.5019441025.99
97*247.000BerkeliumBk986014.7819491026.20
98*251.000CaliforniumCf900015.1019501026.28
99*252.000EinsteiniumEs86000.0019521026.42
100*257.000FermiumFm1,52700.0019521026.50
101*258.000MendeleviumMd000.0019551026.58
102*259.000NobeliumNo82700.0019581026.65
103*262.000LawrenciumLr1,62700.0019611024.90
104*261.000RutherfordiumRf000.00196440.00
105*262.000DubniumDb000.00196750.00
106*266.000SeaborgiumSg000.00197460.00
107*264.000BohriumBh000.00198170.00
108*277.000HassiumHs000.00198480.00
109*268.000MeitneriumMt000.00198290.00
No.
Atomic
weight
NameSym.M.P.
(°C)
B.P.
(°C)
Density*
(g/cm3)
Earth crust
(%)*
Discovery
(Year)
Group*Electron configurationIonization
energy (eV)

Notes:
• Density of elements with boiling points below 0°C is given in g/l. In a sorted list, these elements are shown before other elements that have boiling points >0°C.
• Earth crust composition average values are from a report by F. W. Clarke and H. S. Washington, 1924. Elemental composition of crustal rocks differ between different localities (see article).
Group: There are only 18 groups in the periodic table that constitute the columns of the table. Lanthanoids and Actinoids are numbered as 101 and 102 to separate them in sorting by group.
• The elements marked with an asterisk (in the 2nd column) have no stable nuclides. For these elements the weight value shown represents the mass number of the longest-lived isotope of the element.

Abbreviations and Definitions:

Atomic Number of Thallium. Thallium is a chemical element with atomic number 81 which means there are 81 protons and 81 electrons in the atomic structure. The chemical symbol for Thallium is Tl. Atomic Mass of Thallium. Atomic mass of Thallium is 204.3833 u.

No. - Atomic Number; M.P. - melting point; B.P. - boiling point

Atomic number: The number of protons in an atom. Each element is uniquely defined by its atomic number.

Atomic mass: The mass of an atom is primarily determined by the number of protons and neutrons in its nucleus. Atomic mass is measured in Atomic Mass Units (amu) which are scaled relative to carbon, 12C, that is taken as a standard element with an atomic mass of 12. This isotope of carbon has 6 protons and 6 neutrons. Thus, each proton and neutron has a mass of about 1 amu.

Isotope: Atoms of the same element with the same atomic number, but different number of neutrons. Isotope of an element is defined by the sum of the number of protons and neutrons in its nucleus. Elements have more than one isotope with varying numbers of neutrons. For example, there are two common isotopes of carbon, 12C and 13C which have 6 and 7 neutrons respectively. The abundances of different isotopes of elements vary in nature depending on the source of materials. For relative abundances of isotopes in nature see reference on Atomic Weights and Isotopic Compositions.

Atomic weight: Atomic weight values represent weighted average of the masses of all naturally occurring isotopes of an element. The values shown here are based on the IUPAC Commission determinations (Pure Appl. Chem. 73:667-683, 2001). The elements marked with an asterisk have no stable nuclides. For these elements the weight value shown represents the mass number of the longest-lived isotope of the element.

Electron configuration: See next page for explanation of electron configuration of atoms.

Ionization energy (IE): The energy required to remove the outermost electron from an atom or a positive ion in its ground level. The table lists only the first IE in eV units. To convert to kJ/mol multiply by 96.4869. Reference: NIST Reference Table on Ground states and ionization energies for the neutral atoms. IE decreases going down a column of the periodic table, and increases from left to right in a row. Thus, alkali metals have the lowest IE in a period and Rare gases have the highest.

Other resources related to the Periodic Table

  • Chemical Evolution of the Universe

Thallium

Atomic Number:81Atomic Radius:196 pm (Van der Waals)
Atomic Symbol:TlMelting Point:304 °C
Atomic Weight:204.38Boiling Point:1473 °C
Electron Configuration:[Xe]6s24f145d106p1Oxidation States:3, 2, 1, −1, −2, −5[2]

Periodic Table Atomic Number 81

History

Thallium Atomic Model

From Greek thallos, meanin a green shoot or twig. Thallium was discovered spectroscopically in 1861 by Crookes. The element was named after the beautiful green spectral line, which identified the element. The metal was isolated both by Crookes and by Lamy in 1862 at about the same time.

Sources

Thallium occurs in crooksite, lorandite, and hutchinsonite. It is also present in pyrites and is recovered from the roasting of this ore in connection with the production of sulfuric acid. It is also obtained from the smelting of lead and zinc ores. Extraction is somewhat complex and depends on the source of the thallium. Manganese nodules, found on the ocean floor, contain thallium.

Properties

What element has atomic number 81

When freshly exposed to air, thallium exhibits a metallic luster, but soon develops a bluish-gray tinge, resembling lead in appearance. A heavy oxide builds up on thallium if left in air, and in the presence of water the hydride is formed. The metal is very soft and malleable. It can be cut with a knife. Twenty five isotopic forms of thallium, with atomic masses ranging from 184 to 210 are recognized. Natural thallium is a mixture of two isotopes. A mercury-thallium alloy, which forms a eutectic at 8.5% thallium, is reported to freeze at -60C, some 20 degrees below the freezing point of mercury.

Handling

The element and its compounds are toxic and should be handled carefully. Contact of the metal with skin is dangerous, and when melting the metal adequate ventilation should be provided. Exposure to thallium (soluble compounds) - skin, as Tl, should not exceed 0.1 mg/m3 (8-hour time-weighted average - 40-hour work week). Thallium is suspected of carcinogenic potential for man.

Uses

Thallium sulfate has been widely employed as a rodenticide and ant killer. It is odorless and tasteless, giving no warning of its presence. Its use, however, has been prohibited in the U.S. Canucks twitter march madness. since 1975 as a household insecticide and rodenticide. The electrical conductivity of thallium sulfide changes with exposure to infrared light, and this compound is used in photocells. Thallium bromide-iodide crystals have been used as infrared optical materials. Thallium has been used, with sulfur or selenium and arsenic, to produce low melting glasses with become fluid between 125 and 150C. These glasses have properties at room temperatures similar to ordinary glasses and are said to be durable and insoluble in water. Thallium oxide has been used to produce glasses with a high index of refraction, and is used in the manufacture of photo cells. Thallium has been used in treating ringworm and other skin infections; however, its use has been limited because of the narrow margin between toxicity and therapeutic benefits.

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