As i know, the metallic structure for example a pure copper metal

[Yh Hoo]

As i know, the metallic structure for example a pure copper metal which is made up of all metal atoms that is the copper atoms actually have all its atom of metallic element bonded together by metallic bonding. Metallic bonding is the electrostatic force of attraction between the positively charged metal cations and the delocalized electrons that contribute to the negatively charged electrons cloud right?? (as in my picture)

My Question is why electrons cloud is formed in metallic structure only instead of semiconductor and insulator ??

And when electric field due to the electrical potential difference is created across the metal, is it the delocalized electrons in the electrons sea are made to move in a specific direction and constitute an electric current ??

 

[sophiecentaur]

I think you have your question slightly 'the wrong way round'. If the energy which keeps an outer electron associated with any particular atom is not significantly different from that which attracts it to a nearby atom then the electron can move from atom to atom easily (you used the well known term "de-localised"). For all atoms (or mixtures of atoms) with that energy situation, the bonding will be similar - we refer to it as metallic bonding and we group these elements under the common heading of Metals. It applies to the majority of all elements, in fact.. Also, associated with the highly mobile electrons in metals, is the high thermal and electrical conductivity.
When the atomic structure is different, the mechanical properties will be affected. The atoms of non-metallic elements often combine with co-valent bonding, where two atoms can exist close together and 'share' an electron because, in this condition, the energy is a minimum (hence they stick together). In Ionic Bonding, there is a similar situation in which the lowest energy state is when one atom actually loses one electron and the other gains one - again, the electron in question is tightly associated with just the particular pair of atoms - another potential energy minimum.
So it's not so much a matter of 'Why does it happen in metals?" so much as "what do you call all elements that behave like this?"

 

[Yh Hoo]

If the energy which keeps an outer electron associated with any particular atom is not significantly different from that which attracts it to a nearby atom then the electron can move from atom to atom easily (you used the well known term "de-localised"). For all atoms (or mixtures of atoms) with that energy situation, the bonding will be similar - we refer to it as metallic bonding and we group these elements under the common heading of Metals. It applies to the majority of all elements, in fact.. Also, associated with the highly mobile electrons in metals, is the high thermal and electrical conductivity.

Thanks for your reply,is it the energy (1st bold) u meant refers to the attractive force(coulomb force) between the positively charged nucleus of the atom and the negatively charged electrons in valence shell??
and what is actually meant by the force (2nd bold) ?? attractive force from nucleus of other atoms ??
and can you please explain to me how the electrons cloud is created and moves when an electric field is created ??
Thanks a lot.

 

[sophiecentaur]

Actually, it's the energy to move the electron rather than the force that counts. Energy (or work) needed is to do with force AND the distance moved. It may sometimes be just a matter of force but if that force acts over a large displacement, then the energy involved can be very great compared with when the force 'gives up' after a small displacement. So we talk in terms of energy to get the right answer. Sounds nitpicking but very relevant.