Need help with periodic table!

[Howard]

Why does density increase as you go from left to right across the periodic table to around the middle element, and then decreases from that element all the way to the left?

This is not atomic density, BTW.

 

[Howard]

Help!

 

[Howard]

^

 

[Howard]

Maybe this will clarify.

 

[eakers]

shielding effect

 

[johnjbruin]

took chem in HS a while ago.
I guess something to do with covalent bonds vs metallic bonds. How the molecules are formed and bond together.
This is a wild guess btw.

 

[Howard]

eakers, would you clarify 'shielding effect'?

John, these are elements. No bonds are involved.

 

[pandapanda]

Electron orbitals and the order they are filled in. Try writing down several electron configurations from a particular row using the s, p, d, f format. If necessary draw them. You will see that the ones in the middle have more electrons closer to the nucleus because of the order in which the shells are filled.

Panda

 

[Howard]

Dude, I just said in the first post that I wasn't asking about atomic density. I'm asking about density in x g/cm^3.

 

[YetioDoom]

Originally posted by: Howard
Dude, I just said in the first post that I wasn't asking about atomic density. I'm asking about density in x g/cm^3.

Dude, the atomic density will affect the macroscopic density, so it is about the atomic density.

 

[kt]

Originally posted by: Howard
Dude, I just said in the first post that I wasn't asking about atomic density. I'm asking about density in x g/cm^3.

Dude, read pandapanda's reply. The size of the electron orbit affects the volume of the element and the amount electrons orbiting within this volume affects the density of the element. If you try to write up the orbit configuration, you prolly find that the middle elements have all their inner orbits mostly filled.