Bananas are rich
in potassium-40, a
of potassium. In
a single banana, the
potassium-40 produces a positron, the
antimatter version of
the electron, a dozen
or so times a day, as
well as an electron
about 13 times a
19 20 21 22 23 24 25 26 27
37 38 39 40 41 42 43 44 45
55 56 71 72 73 74 75 76 77
57 58 59 60 61 62 63
89 90 91 92 93 94 95
87 88 103 104 105 106 107 108 109
Ac Th Pa U Np Pu Am
La Ce Pr Nd Pm Sm Eu
Fr Ra Lr Rf Db Sg Bh Hs Mt
Cs Ba Lu Hf Ta W Re Os Ir
Rb Sr Y Zr Nb Mo Tc Ru Rh
K Ca Sc Ti V Cr Mn Fe Co
Recognize these rows and columns?
You may remember a detail or two
about this mighty table’s organization
from a long-ago chemistry class. Elements are ordered according to their
number of protons, or atomic number.
Metals are mostly to the left and nonmetals to the right. The column at the
far right holds the noble gases, named
for their general unwillingness to
interact with other elements.
When Dmitrii Mendeleev proposed
his periodic table 150 years ago, no one
knew what was inside an atom. Today,
we know that an element’s place on
the table, along with its chemical
Not everyone is convinced that lutetium
and lawrencium belong
in the positions shown
here. The Royal Society
of Chemistry instead
puts lanthanum and
actinium in these
boxes, prioritizing outer
and sticking lutetium
and lawrencium at the
end of the f-block below.
The International Union
of Pure and Applied
for chemical naming,
has been exploring the
Out of the lab
The periodic table is an organized grid
When Henri Becquerel, a French physicist,
placed uranium salts atop photographic
plates in 1896, he accidentally discovered
radioactivity, for which he won the Nobel
Prize in physics in 1903. Uranium is the last
element on the table that occurs in any
meaningful abundance in nature; the rest
must be created in the lab.
with tales to tell By Elizabeth Quill
properties, has a lot to do with the element’s proton number as well as how
its electrons are configured.
In one glance, you can see the elements that make up nature’s entire
repertoire of chemical substances
plus how those elements relate to one
another. But the elements are also individuals, with scientific idiosyncrasies
and nuanced stories of discovery. A few
of our favorites are on these pages.
And the table is still a work in progress. Four elements were named as
recently as 2016 (SN: 7/9/16, p. 16).
Boundary-busting research efforts,
along with scientific mysteries, remain.