[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. 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. 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.

[throwaway_yy2Di]

I don't think that's ruthenium -- that graph has a gap at technetium (Z=43), which has no long-lived isotopes. The line actually joins Z=42 and Z=44.

(Might also be confusing that Sn (Z=50) is labelled at the wrong place (Z=48)).

edit: here's a modified version,

https://i.imgur.com/0iQ6vNX.png

[stephengillie]

The underlying mechanics are highly theoretical, but it has something to do with the quarks that compose protons and neutrons. The Strong force is theorized to be caused by color-charge attraction. It would be the same situation as if photons (light, etc) were highly magnetic, they'd attract molecules; in this way the charge carriers of the 3-way color force are highly (and mutually) attracted to quarks for their color-charge.

There's a radius for color-charge interaction. This radius is thought to be one cause for larger elements being less likely to be stable; when protons are too far apart to exchange color-charge carriers, their magnetic repulsion can disrupt nucleic stability.

And different quarks have different energies. Every neutron has 2 Down quarks and 1 Up quark (UDD); every proton has 1 Down quark and 2 Up quarks (UUD). Down quarks are more energetic (massive) than Up quarks. After about 5 minutes, a neutron (UUD) decays into a proton (UDD), an electron, and an electron neutrino. This would seem to imply that an electron and a neutrino would equal the difference between an Up and Down quark.

All protons and neutrons have 3 quarks. There are other particles with 2, but they're much more rare. Nuclei with an odd number of nucleons (protons and neutrons) would have to have an even number of quarks. There may be something to the number of quarks, research into that is difficult because the act of pulling quarks apart requires so much energy that it just creates new quarks.

[1]http://en.wikipedia.org/wiki/Neutron

[peter303]

alpha fusion (He nucleus) is lower energy than proton fusion

[loceng]

How odd..

[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)

[ethbro]

Was going to say, read that, did it in my head.

D1 = {E,O} D2 = {E,O} *Where E and O are balanced in terms of possible outcomes that satisfy

Outcomes: {EE, EO, OE, OO} Odd outcomes: {EO, OE}

Half.

[autokad]

oh yeah your right

[autokad]

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

[learnstats2]

This is a really interesting thought. Assuming you can only add two atoms at random, there are four options:

odd + odd = even (odd reduced by 2, evens increased by 1)

odd + even = odd (evens reduced by 1)

even + odd = odd (evens reduced by 1)

even + even = even (evens reduced by 1!)

When the evens outnumber the odds, odd+odd will be rare, so the percentage of evens will tend to decrease until it reaches 50%.

No matter many of each type you start with, the equilibrium position is 50-50% odd and even.

However: there may be an exception to this. If all the odds are in one place, then odd-odd may be more likely than random. If you have all evens in one place, you can't get back to having odds again - you can't (ever) increase the number of odds that already exist to balance things out, you can only decrease the evens. 0-100% odd and even could also be an equilibrium position.