
What's the third most common element? - ahaefner
https://medium.com/starts-with-a-bang/what-s-the-third-most-common-element-e31790e3638
======
natejenkins
What caught my eye was the oscillation in the abundancy graph, there is a
tendency for even atomic number elements to be more abundant than odd atomic
number elements. Looking at the original Wikipedia article leads to the Oddo-
Harkins rule
[http://en.wikipedia.org/wiki/Oddo%E2%80%93Harkins_rule](http://en.wikipedia.org/wiki/Oddo%E2%80%93Harkins_rule).
There is more discussion on the stability of even vs odd atomic number
elements here:
[http://en.wikipedia.org/wiki/Even_and_odd_atomic_nuclei](http://en.wikipedia.org/wiki/Even_and_odd_atomic_nuclei).
From the latter link, roughly 60% of stable nuclei have an even number of
protons and an even number of neutrons. Only 2% have an odd number of protons
and an odd number of neutrons.

It would be nice if someone could explain any of the exceptions to the Oddo-
Harkins rule, such as the dip at atomic number 44, Ruthenium.

~~~
autokad
when you roll 2 dice, you get a lot more evens than odds.

i imagine the same principle holds. if an odd (Hydrogen) forms with another
odd, you get even. Hydrogen+helium=odd, but helium + helium = even. as the
evens outnumber the odds, even more evens are forming with evens.

~~~
Someone
No, you don't 1+3+5+5+3+1 = 2+4+6+4+2

(1/36 probability of a sum of 2, 3/36 of a sum of 4, etc)

~~~
autokad
oh yeah your right

~~~
autokad
not sure why i was down voted for admitting I was wrong, assholes.

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Agathos
What are the six most common elements in the universe?

H, He, C, N, O, Ne

What are the four most common elements in living cells?

H, C, N, O

(We invited the noble gasses to play, too, but they said something along the
lines of, "Go away you peasants you'll mess up our perfect orbitals.")

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ghubbard
What's the third most common element (in the universe)?

tl;dr: Oxygen

But it's worth reading the article to learn why.

~~~
gpvos
Note that the very interesting graph near the end of the article actually
displays element abundance in the _solar system,_ not in the universe. (Found
that out when looking it up in Wikipedia.) The article misrepresents this!

~~~
SquareWheel
I also searched it up on Wiki. They have a larger version of the image, and a
data source.

Link:
[http://commons.wikimedia.org/wiki/File:Nucleosynthesis_perio...](http://commons.wikimedia.org/wiki/File:Nucleosynthesis_periodic_table.svg)

~~~
gpvos
And the one that I actually meant:
[https://commons.wikimedia.org/wiki/File:SolarSystemAbundance...](https://commons.wikimedia.org/wiki/File:SolarSystemAbundances.png)

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arto
As for lithium (the third-most abundant element after the Big Bang, at
0.00000001% of nuclei), it so happens I was just reading the James S. A. Corey
novel _Cibola Burn_ where it plays a role:

"People used to think gold was worth fightin' over, and that shit gets made by
every supernova, which means pretty much every planet around a G2 star will
have some. Stars burn through lithium as fast as they make it. All the
available ore got made at the big bang, and we're not doin' another one of
those. Now _that 's_ scarcity, friend."

~~~
hga
Naw, or at least according to what I've been reading lately we get lithium and
a number of other light elements from cosmic ray spallation:
([https://en.wikipedia.org/wiki/Cosmic_ray_spallation](https://en.wikipedia.org/wiki/Cosmic_ray_spallation)
so it's happening all the time.

~~~
hashmymustache
Reminded me how crazy it is that we're in a time where we've legitimized the
fabled goal of alchemic transmutation - we can turn mercury to gold. Turns out
the philosopher's stone was a particle accelerator.

~~~
hga
Don't forget about the incomplete specification problem:

 _You wanted non-radioactive gold for your jewlery and dental fillings? Oops,
sorry about that...._

([https://en.wikipedia.org/wiki/Isotopes_of_gold](https://en.wikipedia.org/wiki/Isotopes_of_gold))

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Jugurtha
Nice read, and pretty neat periodic table.

PS: People might also like "Atomic Physics and Human Knowledge"[0] by Niels
Bohr. It's a quick read (less than 60 pages).

[0]:
[https://archive.org/details/AtomicPhysicsHumanKnowledge](https://archive.org/details/AtomicPhysicsHumanKnowledge)

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elros
I would say `p`, right after `div` and `span`

~~~
stephancoral
Wouldn't <html>, <head>, and <body> be the three most common?

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Jack000
but they occur only once per page

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scotty79
Is big bang necessary for this or does any amount of photons of insanely high
energy crystallize in matter in those proportions?

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gus_massa
The Hydrogen-Helium ratio is very related to the details of the Big Bang. From
[http://hyperphysics.phy-
astr.gsu.edu/hbase/astro/hydhel.html](http://hyperphysics.phy-
astr.gsu.edu/hbase/astro/hydhel.html)

> _Basically, the hydrogen-helium abundance helps us to model the expansion
> rate of the early universe. If it had been faster, there would be more
> neutrons and more helium. If it had been slower, more of the free neutrons
> would have decayed before the deuterium stability point and there would be
> less helium._

~~~
scotty79
> If it had been faster ... > If it had been slower ...

Isn't the inflation conceived to be as fast and long as necessary so that
inputs to baryogenesis give result with hydrogen to helium ratios that are in
line with experimental data?

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solve
Tell me more about the creation of the elements that "come from cosmic rays".

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jakobegger
The graph at the bottom of the post would greatly profit from horizontal
gridlines.

~~~
throwaway_yy2Di
Here you go,

[https://i.imgur.com/Bgttnqh.png](https://i.imgur.com/Bgttnqh.png)

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mrfusion
I've always wondered how elements produced in past stars end up in our solar
system. I wouldn't think the whole universe is getting remixed all the time.
It seems like areas stay pretty isolated.

~~~
simonh
At the universal scale, we can observer several galaxies in various stages of
colliding with each other (1). In fact our galaxy and Andromeda are on course
to collide with each other in about 4 billion years (2).

Massive stars end their lifecycle in a supernova explosion, which blasts much
of their mass off into space. the remaining stellar core either forms a
neutron star or a black hole. The mass that is blated off contains many heavy
elements formed in the star by nuclear fusion, and contributes to nebula
formation. These nebulas coalesce to form new stars and their associated
planetary systems. We can actualy see this happening in various places
throughout our galaxy, with nebulas in various stages of coalescing and with
multiple stars forming within them. Absorbtion spectra tell us about the
materials these nebulae are composed of.

There is some speculation that heavy elements such as iron are also produced
and scattered about in nutron star collisions.

(1)
[http://en.wikipedia.org/wiki/Galaxy_collision](http://en.wikipedia.org/wiki/Galaxy_collision)
(2)
[http://en.wikipedia.org/wiki/Andromeda_galaxy#Future_collisi...](http://en.wikipedia.org/wiki/Andromeda_galaxy#Future_collision_with_the_Milky_Way)

~~~
mrfusion
Interesting. So where did our sun come from? Are you saying it started from a
multilight year wide cloud?

Why is it 4+ light years from any other stars? Did our sun pull everything out
of that radius when it was forming leaving a whole bunch of empty interstellar
space?

~~~
simonh
Bear in mind the galaxy is continuously rotating, our sun is orbiting the
galactic nucleus, as are the other stars around it. Right now the nearest star
is 4 lightyears away, but that's not always the case and it's quite likely
other stars have passed ours by much closer than that during it's lifetime. In
fact our sun has orbited the galactic core many times; it does so roughly
every 250 million years.

The sun would have accumulated material from the nebula it formed in as it
drifted though it. The stars near us now are not the ones our sun was near
when it formed though (except by extemely unlikely co-incidence), as each star
is on a slightly different course round the galaxy, like water droplets in a
very slowly rotating cyclone.

If another star were to pass by very close, it could be disastrous for us as
it could severely disrupt the planetary orbits in our system, but that's
fairly unlikely and there's no prospect of that happening for many millions of
years at least. The space between stars is vast, even by comparrison to the
size of stars themselves and their solar systems.

EDIT - on that last point, 4 ly is ~250,000 AU (the distance from the earth to
the sun). If we asume out solar system is 100 AU across, that's still only
1/2500 the distance to the next star.

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mrfusion
(Maybe it was XKCD that gave me the idea?) But I remember thinking it
interesting that humans are the chemical/physical process that creates those
highest elements.

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BFay
Did anybody else click on this expecting a DOM element? I was guessing <p>

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Youpinadi
the "a" element (after div and span)

~~~
gpmcadam
It says "it starts with a bang" so I was thinking <!doctype> after <html> and
<body> :)

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evantahler
Surprise?

~~~
gpvos
Well, yeah. I thought it was carbon, and I thought it was way ahead of the
others. But instead there are actually a bunch of elements vying pretty
closely for third position: oxygen, carbon, neon, nitrogen, magnesium,
silicium, iron, sulphur. (Although one should keep in mind that the graph is
logarithmic.)

Note that the graph actually shows the estimated abundance of elements in the
_solar system_ (found that on Wikipedia), not the universe or the Milky Way.
The article misrepresents that!

~~~
Terr_
I thought he was making a Terry Pratchett reference.

> The world is made up of four elements: Earth, Air, Fire and Water. This is a
> fact well known even to Corporal Nobbs. It's also wrong. There's a fifth
> element, and generally it's called Surprise.

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ilovefood
Love it!!! great share!

~~~
gpvos
Please just upvote the post instead.

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maaaats
Please just downvote the comment instead. ;)

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sltkr
I think in cases where the original comment appears to be made in good faith,
it's OK to explain what's wrong with it/what to do instead. That's how people
learn.

(Obvious spam/flames/etc. should just be downvoted, ofcourse.)

~~~
gjm11
Yup.

It seems like about half of _ilovefood_ 's comments are of the "wow! great
article!" type. I'm not sure whether this indicates that comments saying
"don't do that" are likely to be helpful or not...

(If it were 100%, I'd conclude that it's a would-be spammer's account,
building up a bit of history before starting to try to fill HN with spam. But
I don't think that's what's going on here.)

