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16O

Oxygen-16 is a stable isotope of the element oxygen with mass number 16. It has eight protons and eight neutrons. It is by far the most abundant oxygen isotope in Earth's atmosphere and crust, accounting for about 99.76% of natural oxygen. Its nuclear spin is 0+, and it does not undergo radioactive decay.

The nucleus of 16O is doubly magic, with filled shells for both protons and neutrons (Z=8, N=8),

In astrophysics, 16O is primarily produced during helium burning in stars via the fusion reaction 12C(alpha,gamma)16O,

In laboratory science, 16O serves as a standard reference isotope in isotope ratio mass spectrometry. Its stability

contributing
to
unusually
high
binding
energy
for
its
size.
The
binding
energy
per
nucleon
is
about
7.98
MeV,
giving
a
total
binding
energy
near
128
MeV.
This
makes
16O
one
of
the
most
strongly
bound
light
nuclei.
and
it
is
a
major
product
of
stellar
nucleosynthesis.
In
the
solar
system
and
on
Earth,
16O
dominates
the
isotopic
composition
of
oxygen,
with
17O
and
18O
present
at
roughly
0.037%
and
0.204%
respectively.
The
isotope
ratios
of
oxygen
in
water
are
used
as
tracers
in
climate
and
hydrology
studies.
and
abundance
make
it
a
common
baseline
for
calibrations
and
for
studies
of
nuclear
structure,
stellar
evolution,
and
planetary
science.