Cobalt is element number 27, a metal with the symbol Co. Its name comes from the German word for a goblin, Kobold.
Atomic number 2758.93
CoCobaltコバルト (kobaruto)
Symbol
Co
Atomic weight
58.93
Place in the table
Period 4 · Group 9
Atomic weight from the Chemical Society of Japan, “Table of Standard Atomic Weights with Four Significant Figures (2026)”.
The mine goblin
The symbol Co comes from the German Kobold, a goblin that turned silver ore into cobalt ore. Cobalt was discovered in 1735.
The name of its neighbor nickel (Ni) also comes from German, from a word meaning “false copper.”
A battery material
In their 1985 patent, Akira Yoshino and colleagues, winners of the 2019 Nobel Prize in Chemistry, used a compound of lithium and cobalt for the positive side of the lithium-ion battery.
Cobalt is in the fourth row of Group 9, between iron and nickel.
Think about it
Q1Why do you think miners long ago blamed a goblin?
Q2Iron, cobalt and nickel are neighbors on the periodic table. Are they alike in any way?
Q3When choosing materials for a battery, what do you think matters most?
There is no single right answer. Talking it over with someone at home is a good way to learn.
Did you know? — Cobalt and nickel both get their names from German. Most symbol origins are Latin or Greek, but some elements come from German.