33
As
Metalloid

Arsenic

Atomic number 33 · Period 4 · Block P

As · Arsenic
Mendeleev.com

Understanding the element

Arsenic (As) is chemical element 33. It belongs to the metalloids, and its reference state at room temperature is a solid. Those basic facts are a useful starting point for its chemistry and applications.

Where do we encounter it?

In practice, it turns up most often in semiconductors, alloys and wood preservation.

semiconductorsalloyswood preservation
Standard atomic weight74.921595(6)

What its position in the table tells us

Arsenic sits in period 4, group 15 and the P block. That location is useful because neighbouring elements often share trends in valence electrons, oxidation states and bonding behaviour.

Worth remembering
Arsenic has a characteristic place in the periodic table that helps explain both its chemistry and its practical uses

Scientific sources

Element identity
Atomic number33
Group15
Period4
BlockP
CategoryMetalloid
PhaseSolid