Element 81 of Periodic table is
Thallium with atomic number 81,
atomic weight 204.3833.
Thallium, symbol Tl, has a
Simple Hexagonal structure and Silver color.
Thallium is a post-transition metal element.
Trivial name of Thallium is triels, icosagens.
Know everything about Thallium Facts, Physical Properties, Chemical
Properties, Electronic configuration, Atomic and Crystal Structure.
Thallium is a chemical element with symbol Tl and atomic number 81. This soft gray post-transition metal is not found free in nature. When isolated, it resembles tin, but discolors when exposed to air.
Read key information and facts about element Thallium
Explore our interactive periodic table
Periodic table is arranged by atomic number, number of protons in the nucleus which is same as number of
The atomic number increases from left to right. Periodic table starts at top left ( Atomic number 1) and
ends at bottom right (atomic number 118). Therefore you can directly look for atomic number
81 to find Thallium on periodic table.
Another way to read periodic table and locate an element is by using group number (column)
and period number (row). To locate Thallium on periodic
table look for cross section of group 13 and period
6 in the modern periodic table.
Interactive Periodic Table to Understand
and Learn Cool Trends
The element Thallium was discovered by William Crookes in year
1861 in United Kingdom
derived its name from the Greek thallos, 'green twig'
The table below shows the abundance of Thallium in Universe, Sun, Meteorites,
Earth's Crust, Oceans and Human Body.
The solid state structure of Thallium is Simple Hexagonal.
The Crystal structure can be described in terms of its unit Cell. The unit Cells repeats itself in
dimensional space to form the structure.
The unit cell is represented in terms of its lattice parameters, which are the lengths of the cell
Lattice Constants (a, b and c)
and the angles between them Lattice Angles (alpha, beta and gamma).
The positions of the atoms inside the unit cell are described by the set of atomic positions (
xi, yi, zi) measured from a reference lattice point.
The symmetry properties of the crystal are described by the concept of space groups. All possible
symmetric arrangements of particles in three-dimensional space are described by the 230 space groups
(219 distinct types, or 230 if chiral copies are considered distinct.
Thallium atoms have 81 electrons and
the electronic shell structure is [2, 8, 18, 32, 18, 3] with Atomic Term Symbol (Quantum Numbers) 2P1/2.
Shell Structure of Thallium - Electrons per energy
The ground state electronic configuration of Neutral Thallium atom is
[Xe] 4f14 5d10 6s2 6p1.
The portion of Thallium configuration that is equivalent to the noble gas of
the preceding period, is abbreviated as [Xe]. For atoms with many electrons, this
notation can become lengthy and so an abbreviated notation is used.This is important as it is
the Valence electrons 4f14 5d10 6s2 6p1, electrons in
the outermost shell that determine the chemical properties of the element.
Complete ground state electronic configuration for the Thallium atom, Unabbreviated electronic configuration
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f14 5d10 6s2 6p1
Thallium atomic radius is 156 pm, while it's covalent radius is 148 pm.
The electron affinity of Thallium is 19.2 kJ/mol
Refer to table below for Ionization energies of Thallium
Refer to below table for Thallium Physical Properties
Thallium is Conductor of electricity. Refer to
below for the Electrical properties of Thallium
Refer to table below for Thermal properties of Thallium
Isotopes of rhodium. Naturally occurring Thallium has
2 stable isotope -
List of unique identifiers to search the element in various chemical registry databases