1811: Iodine - The book of science

Iodine
Atomic number 53
Stuff that stings
Commentary

Dijon—Bernard Courtois elements

Iodine

It was an accident, but
Bernard Courtois realized
he had found something new,
an element that no one else
had previously described.
Courtois was processing
seaweed for sodium carbonate,
but he added too much acid,
making a cloud of purple vapor
that crystallized on cold surfaces.
Courtois gave samples
to Ampère and Gay-Lussac,
who confirmed the discovery,
and Ampère gave some to Davy,
who named it iodine.

Atomic number 53

Dietary supplement (essential for life)
Disinfectant (antibacterial and antiviral)
Staining (for starch or cancerous tissue)
And protecting the thyroid from nuclear fallout
(just in case)

Stuff that stings

A glass rod was attached to the lid
of the little bottle of tincture of iodine.
Mom would wipe its cold glass knob
over a cut to apply the rusty iodine.
That stuff would sting like heck.
Man, that stuff would sting like heck.

Iodine is named after the color of its violet vapor. Tincture of iodine for topical application (2% in ethanol and water) had more of a rusty color.

See also in The book of science:

1869—Periodic table—Dmitri Mendeleev

Readings on wikipedia:

“Bernard Courtois”
“Iodine”
“Tincture of iodine”
“Timeline of chemical element discoveries”

Other readings:

“Iodine,” Elementymology & Elements Multidict, by Peter van der Krogt