need help solving extra credit riddle

[Belties R Us]

I am nothing without it, one "n-less" word;
I am he without breath, placed after the third.
In a fortnight I'm there, where before I've been;
If you see my reflection, you'll know what I mean.

What am I?

Its for chemistry class extra credit. Please help.

 

[cmf1]

Man in the moon?

 

[upfrombottom]

The tide?

 

[ga.prime]

A Beryllium atom that had a really loose covalent bond with a Ferrous Oxide molecule?

 

[TexasBred]

The "fortnight" keeps blowing me away.

 

[peg4x4]

Beryllium is #4 on the table and has a half life of 56(?) days...

 

[VanC]

Man in the moon?

I'm pretty sure this is the right answer.

 

[mmsubs]

I agree, Man in the Moon

I am nothing without it, one "n-less" word;
One word without "n"

I am he without breath, placed after the third.
man in the moon doesn't breathe, earth is third from the sun

In a fortnight I'm there, where before I've been;
fortnight=14 days, every 14 days it will be in a phase as it was before

If you see my reflection, you'll know what I mean
the sun makes the moon light up

 

[jw]

Man in the Moon is correct. If you search Google, etc.. long enough it will come up.