A lanthanide and a metal element,
soft, malleable and easily bent.
It is silver white, turning yellow,
but the interest in the pure metal is low.

It irritates eyes and skin,
and a little hazardous thing.
Mainly used to dope steel,
there its benefits are real.

Grain refinement, strengthening,
dissolved in iron it is a win.
It is used as well to dope active matter,
to simply make its performance better.

A special application,
is in the nuclear clock application.
The ticking stays stable,
even of terahertz frequencies capable.

It was found from a Swiss chemist,
as fourth element of the erbia ore list
Jean Charles Galissard de Marignac his name,
came as well with the hypothesis of isotopes to fame.

Ytterbium, another lanthanide,
with no particular need,
but a helping hand, it seems,
clocks, steels and active matter means.

If separated from others, it gets irritating,
desperate bond making,
I take from Ytterbium, we can strengthen us together
excluded people tend to turn into explosive matter.