Evening star. [volume] (Washington, D.C.) 1854-1972, 1930-03-30
ATOMIC STRUCTURE
Of LUTECIUM FOUND
Bureau of Standards PhySi-
cist Obtains Spectra Photo
graphs in Study.
BY THOMAS r. HENRY.

At about the same time an almost
parallel discovery at the opposite end
of creation, in the world Of the infinite
ly little. was made at the Bureau of
Standards here.
DR.. william z. Maggers obtained
spectra photographs which revealed
the atomic structure of lutecium. AS
a triumph of pure science it was about
as important and sensational as the
discovery Of the planet.
Everything on earth, in the final
analysis is composed Of atoms. An
atom consists of a central body, some
what like the sun In the solar system,
with from to SO other bodies revolv-
ing around it.
80 Kinds Of Atoms Known.
The number of planets, or electrons
distributed about the central nucleus
determines the kind of atom. Thus, If
there is only one, it is an atom of hydro
gen. If there are g. it is an atom Of
uranium. Ninety kinds Of atoms are
known. The central body increases IN
size proportionate to the number of
It's planetary family.
Nobody will ever see an atom. But
Il has been possible in a roundabout
way to photograph them. That is
DR. Maggers' job. The photographs reveal
how the atrnos are made up. Each ar
rangement Of planetary electrons, when
made luminous, gives on light of a diff
ferent composition. This is divided in
q prism, and the distribution OF spectrum
lines studied.
In this way, it was found, atoms are
built up from the simpler to the more
complex according to q definite pat
tern, which seems to hold throughout
nature. Electrons are arranged in sue
ceSsive shells" around the nucleus
49, IL, Fe sfA1 - 1na
atom, and the first shell" is completed.
The result is helium atom.
Building-u Continues.
Then, by some unexplained increase
In the central mass which attracts other
electrons, the process Of building up the
elements goes on second shell is
built up outside the first When this
Is completed, in this case by eight cleo
irons, the products is neon. A new shell
starts. Finally, with four shells COM
posed Of 81 electrons, is found the rare
gas, xenon. Then begins the process of
building up fifth shell. Electrons are
added until, with three new ones, the
rare metal lanthanum is reached.
There physicists ran into one Of the
great myterieS In the structure OF mat
ter. There we're II spectra, indicating
a elements, the distribution of lines in
which showed that now new electrons
were being added to the incompleted
cutter shell Each had three valence
electrons, or electrons in an incomplete
shell, whereas, according to the law
which had held heretofore, the shell
should have been filled up and the
building Of a new one started.
These IA elements were the So-called
rare eartaS: Certum, praSeodymium
neodymium, illinium, samaritan, euro
peum, gadolinium, terbium, dysprosium,
nolimium, erbiun, thulium, ytterbium
and luceciunn. They existed in small
quantities and were so mixed up with
other elements that it was almost i'm
possible to obtain any specimens Of
them.
BY pre-mathematica analysis and no
physical observations by which to check
his deductions, the Danish physicist
Bohr attempted to explain the curious
behavior of the complicated planetary
systems Of the rare earths BY a proc
eSS Of elimination he arrived at the
conclusion that they must follow a new
system OF atom building. Instead of
completing the unfinished fifth electron
shell of lanthanufa, they started build
ing another shell inside it, leaving the
three outer electF0ns undiSturbed. But
there was no way Of determining wheth-
er Bohr was right or wrong. 1t re-
manned theory interesting to PSYCHE
cists.
When an atom has a completed outer
shell it is self-suficient. It will not
enter into q combination with any other
element. Heliun, with complete outer
shell of two electrons cannot be mixed
With anything. That is why 1t is so
valuable for initiating airships. If it
viii not mix, it cannot explode. There
8 nothing that win explode helium.
Neon has complete outer shell of
eight electrons. It will not mix with
anything. Crypton has a complete
outer shell Of Is electrons. It will not
mix with anything.
1t Is the electrons Of an uncompleted
she'll only which are not firmly bound
20 their own system that can attach
themselves to other atoms Of the same
element or TO other elements If it were
not for this kind Of atoms, there would
be no physical or chemical combina-
lions. There would be no solid matter
N the universe.
Probably Wouldn't Have Light.
Furthermore, there probably would be
no such thing as light. Light is pro-
duced by disturbing the electrons in the
tncompleted outer shells, chiefly by
heat. These loosely attached electrons
must be disturbed in some way. In
such atoms as carbon, 1t Is COMPARE
lively easy to disturb them and cause
them to give of energy and become
luminous. They must be made to emit
light In order to obtain their spectra,
which reveal how they are built. In
such cases the addition Of q new outer
electron causes definite change in the
lines Of the spectrum, so that 1t is Just
rs good as a photograph to the physi-
est. But the rare earths didn't follow
this rule. The spectra were different,
but the lines were so mixed up they
didn't mean much Of anything.
DR.. Maggers attempted the exceed
1ngly difficult job of knocking of all
three outer electrons by means Of an
electric spark, and then obtaining the
spectrum Of what was left. He found
that they were following with mathe-
NAUTICAL exactness Gohr's mathematical
deductions. With the incompleted outer
shell knocked out new shell was be-
ing built up Just the same Lutecium
had complete sixth shell of IA cleo
irons. From the point Of view Of the
oretical physics, it was one of the great
est triumphs ever achieved at the Blu
reau of Standards
DR.. Maggers worked with only about
Q hundredth Of an ounce of lutecium
He plans to carry on the work with the
other rare earth elements. Minute
qualities can be obtained of all but one,
nlinium, which is the latest discovered
and at present the rarest Of all the ma
terials entering into the structure OF
the universe.