Tl
Thallium · element 81
Post-Transition Metal · Solid at room temperature
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.
Key facts
Atomic mass
204.38 u
how heavy one atom is
Phase (room temp.)
Solid
Density
11.85 g/cm³
how tightly packed it is
Melting point
577 K (304 °C)
when solid turns to liquid
Boiling point
1746 K (1473 °C)
when liquid turns to gas
Period
6
its row in the periodic table
Group
13
its column in the periodic table
Block
P-block
the neighbourhood it lives in
Electronegativity
1.62
how strongly it pulls electrons
Electron configuration
[Xe] 4f14 5d10 6s2 6p1
where its electrons live
Shells
2 · 8 · 18 · 32 · 18 · 3
electrons in each layer, inside to out
Discovered by
William Crookes
who found it
Appearance
silvery white
what it looks like
Source: Wikipedia