Why Does Lithium Stay on the Surface of the Sun?

[sawtooth500]

I recently saw a science documentary saying that there is a lot of lithium on the sun's surface - since lithium is heavier than H and He wouldn't it sink to the core of the sun? How does it stay on the surface?

 

[mathman]

It is mainly an effect of temperature. The various nuclides that make up the sun, along with electrons (it is too hot to have atoms) have so much kinetic energy that gravity has very little effect on individual particles.

 

[sawtooth500]

So is that true for all the elements? So suppose I tossed a slab of pure uranium into the sun - I am guessing it would separate the uranium into individual atoms and those would stay at the surface? Or would those sink because U is so much heavier than Li?

 

[Drakkith]

So is that true for all the elements? So suppose I tossed a slab of pure uranium into the sun - I am guessing it would separate the uranium into individual atoms and those would stay at the surface? Or would those sink because U is so much heavier than Li?

I think it would turn to plasma and dilute within the sun. The sun has convection currents so I would expect at least some of it to move through these and to spread throughout the outer region of the sun, but I'm not sure.

 

[Dr_Morbius]

You would need very high gravitational accelerations to cause the heavier atoms to sink. This is the principal that ultracentrifuges use to separate different isotopes of uranium.

http://en.wikipedia.org/wiki/Gas_centrifuge