Mendeleev
Periodic table · chemistry · physics
Element story

Cobalt

Atomic number 27 means that every Cobalt nucleus contains 27 protons. That proton count is the element's identity: change it and you no longer have Cobalt.

Start with the nucleus

Atomic number 27 means that every Cobalt nucleus contains 27 protons. That proton count is the element's identity: change it and you no longer have Cobalt.

Cobalt (Co) is chemical element 27. It belongs to the transition metals, and its reference state at room temperature is a solid. Those basic facts are a useful starting point for its chemistry and applications.

In practice, it turns up most often in batteries, superalloys and pigments.

See the atom

Conceptual visual: electron shells are a learning aid, not a literal picture of quantum orbitals.

What this number means

Atomic number 27 means that every Cobalt nucleus contains 27 protons. That proton count is the element's identity: change it and you no longer have Cobalt.

Keep exploring

→ Cobalt · Atomic structure · Periodic trends

27CoCobalt
Cobalt · Co · Z = 27

Cobalt (Co) is chemical element 27. It belongs to the transition metals, and its reference state at room temperature is a solid. Those basic facts are a useful starting point for its chemistry and applications.

Understanding the element

Cobalt (Co) is chemical element 27. It belongs to the transition metals, 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 batteries, superalloys and pigments.

What its position in the table tells us

Cobalt sits in period 4, group 9 and the D block. That location is useful because neighbouring elements often share trends in valence electrons, oxidation states and bonding behaviour.