Arsenic
A toxic metalloid used in semiconductors and pesticides.
Inside the Arsenic atom
Switch between Bohr and Quantum Cloud modes to compare a simple teaching model with a more realistic probability-based view, and follow the guided tour to explore the Arsenic atom step by step.
Electron configuration
[Ar] 3d10 4s2 4p3
A neutral Arsenic atom has 33 electrons (equal to its proton count). Choosing a different isotope above changes only the neutron count.
Shell distribution
Electrons fill inner shells before outer ones; the outermost (valence) shell drives the element's chemistry.
Physical & atomic properties
- State (room temp)
- Solid
- Melting point
- 1090 K (817 °C)
- Boiling point
- —
- Density
- 5.776 g/cm³
- Electronegativity
- 2.18 Pauling
- Atomic radius
- 115 pm
- 1st ionization energy
- 947 kJ/mol
- Category
- Metalloids
Discovery & naming
- Discovered
- 1250
- Discovered by
- Albertus Magnus
- Origin of name
- Greek 'arsenikon', a yellow pigment.
Notable uses
Semiconductors, wood preservatives, and alloys.
Where Arsenic comes from
Several comparable sources
Both slow neutron capture in dying stars and rapid capture in explosive events contribute meaningfully.
Simplified origin map — many elements form through more than one astrophysical pathway.
Summary
- Atomic number
- 33
- Atomic mass
- 74.922
- Category
- Metalloids
- Group · Period
- 15 · 4
- Block
- p-block
- Shells
- 2 · 8 · 18 · 5