Arsenic

Element 33 on the periodic table, symbol As, group 15, period 4.

Arsenic is a chemical element with symbol As and atomic number 33. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. Arsenic is a metalloid.

Appearance: metallic grey

Properties

Atomic Number: 33
Atomic Mass: 74.9216 u
Group: 15
Period: 4
Block: p-block
Category: Metalloid
State at 25 °C: Solid
Melting Point: Not measured
Boiling Point: Not measured
Density: 5.727 g/cm³
Atomic Radius: 115 pm
Electronegativity: 2.18
Oxidation States: -3, +3, +5
Abundance in Crust: 1.8 mg/kg
Discovered: 1250
Discovered By: Bronze Age

Electron Configuration

[Ar] 3d10 4s2 4p3

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3

Ionisation Energies (kJ/mol)

1. 947
2. 1,798
3. 2,735
4. 4,837
5. 6,043
6. 12,310

Elements near Arsenic

Elements in the same group share the number of outer electrons and behave in similar ways. Elements in the same period share a shell, so they change steadily from left to right.