Arsenic (As)
At normal pressure arsenic skips the liquid phase and turns straight from solid to gas.
Arsenic properties
- Atomic mass
- 74.922 u
- Category
- Metalloid
- Group
- 15
- Period
- 4
- Block
- p-block
- State at room temp.
- Solid
- Electronegativity
- 2.18
- Melting point
- 1,090 K (816.8 °C)
- Boiling point
- 887 K (613.8 °C)
- Density
- 5.727 g/cm³
- Oxidation states
- +5, +3, −3
- Atomic radius
- 185 pm
- Ionization energy
- 9.815 eV
- Electron affinity
- 0.81 eV
- Radioactive
- No, has stable isotopes
- Discovered
- 1250
Arsenic electron configuration
- Electron configuration
- [Ar] 3d10 4s2 4p3
- Full electron configuration
- 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p3
- Electron shells
- 2 · 8 · 18 · 5
The electron configuration of Arsenic (As) is [Ar] 3d10 4s2 4p3. Its 33 electrons are arranged in shells as 2, 8, 18, 5.
Protons, neutrons and electrons in Arsenic
A neutral Arsenic atom has 33 protons and 33 electrons. Most Arsenic atoms have about 42 neutrons: the atomic mass rounded to 75, minus the atomic number 33.
Neutrons are approximate: atoms of the same element can have different numbers of neutrons (isotopes). Atomic number and mass
How many valence electrons does Arsenic have?
5
Arsenic has 5 valence electrons in its outermost shell, shell 4. These are the electrons involved in chemical bonding.
Arsenic orbital diagram
Each box is an orbital that holds up to two electrons with opposite spins (↑↓). The inner shells are the same as the noble gas in brackets. How to write electron configurations
Molar mass of Arsenic
74.922 g/mol
One mole of Arsenic atoms (6.022 × 10²³ atoms) has a mass of 74.922 grams. Use this value to convert between grams and moles.
Arsenic facts
- At normal pressure arsenic skips the liquid phase and turns straight from solid to gas.
- Gallium arsenide is used in high-speed electronics and solar cells for satellites.
- Arsenic (As) has atomic number 33 and is a solid at room temperature. It was discovered in 1250.
Position in the periodic table
Arsenic is element 33, in period 4 and group 15 of the periodic table, in the p-block.
Uses of Arsenic
Arsenic is added in small amounts to lead to harden it, for example in lead-acid battery grids and ammunition. Chromated copper arsenate was long used to protect timber from rot and insects, though its use in homes is now restricted in many countries. Arsenic trioxide is an approved medicine for a type of leukemia, and very pure arsenic is used in semiconductors.
Who discovered Arsenic?
Arsenic compounds such as the yellow mineral orpiment were known in ancient times, but the German scholar Albertus Magnus is traditionally credited with first isolating the element around 1250.
Where does the name come from?
Arsenic comes from the Greek arsenikon, a name for the yellow mineral orpiment, an arsenic sulfide used as a pigment. The Greek word ultimately comes from a Persian word meaning 'golden'.
Same group
Compare Arsenic
FAQ
What is the electron configuration of Arsenic?
The electron configuration of Arsenic (As) is [Ar] 3d10 4s2 4p3. Its 33 electrons are arranged in shells as 2, 8, 18, 5.
How many protons, neutrons and electrons does Arsenic have?
A neutral Arsenic atom has 33 protons and 33 electrons. Most Arsenic atoms have about 42 neutrons: the atomic mass rounded to 75, minus the atomic number 33.
How many valence electrons does Arsenic have?
Arsenic has 5 valence electrons in its outermost shell, shell 4. These are the electrons involved in chemical bonding.
What is the molar mass of Arsenic?
The molar mass of Arsenic is 74.922 g/mol. This is the same number as its atomic mass, 74.922 u.
Is Arsenic a metal?
Not exactly. Arsenic is a metalloid, with properties between those of metals and nonmetals.
Is Arsenic radioactive?
Ordinary Arsenic is not radioactive: it has at least one stable isotope. Like every element, it also has radioactive isotopes, most of them made in laboratories.
Where is Arsenic on the periodic table?
Arsenic is element 33, in period 4 and group 15 of the periodic table, in the p-block.