81 Tl 204.38
Thallium
post-transition metal
Properties
- Atomic number
- 81
- Atomic mass
- 204.38 u
- Category
- post-transition metal
- Group
- 13
- Period
- 6
- Block
- p-block
- State (room temp)
- Solid
- Outer-shell electrons
- 3
- Electronegativity
- 1.62 (Pauling)
- Density
- 11.85 g/cm³
- Melting point
- 303.85 °C
- Boiling point
- 1472.85 °C
Electron configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p¹
Noble-gas shorthand: [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p¹
Electrons per shell: 2, 8, 18, 32, 18, 3, which is 3 in the outermost shell.
Related: electron configuration, the Bohr model, valence electrons.
About Thallium
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.
- Discovered by William Crookes
- Appearance: silvery white
Thallium: frequently asked questions
- What is Thallium?
- Thallium (Tl) is the chemical element with atomic number 81. It is a metal: specifically a post-transition metal.
- What is the atomic number of Thallium?
- Thallium's atomic number is 81, which means every Thallium atom has 81 protons in its nucleus.
- What is the electron configuration of Thallium?
- The electron configuration of Thallium is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p1 (noble-gas shorthand: [Xe] 4f14 5d10 6s2 6p1). Its electrons are arranged in shells of 2, 8, 18, 32, 18, 3, with 3 in the outermost shell.
- Is Thallium a metal or a nonmetal?
- Thallium is a metal: specifically a post-transition metal.
- What group and period is Thallium in?
- Thallium is in group 13 and period 6 of the periodic table.
- Is Thallium a solid, liquid, or gas?
- At room temperature, Thallium is a solid.
Position in the periodic table
Data compiled from Wikipedia, PubChem, and IUPAC. Source.