Metallic Bonding Information Sheet Template printable pdf download

Metallic Bonding

Metals have several qualities that are unique, such as the ability to conduct electricity, a low

ionization

energy, and a low

electronegativity

(so they will give up electrons easily, i.e., they are cations). Their physical properties include a lustrous

(shiny) appearance, and they are malleable and ductile. Metals have a crystal structure.

• Metals that are malleable can be beaten into thin sheets, for example: aluminum foil.

• Metals that are ductile can be drawn into wires, for example: copper wire.

In the 1900's, Paul Drüde came up with the sea of electrons theory by modeling metals as a mixture of atomic cores

(atomic cores = positive nuclei + inner shell of electrons) and valence electrons. In this model, the valence electrons are

free, delocalized, mobile, and not associated with any particular atom. For example: metallic cations are shown in green

surrounded by a "sea" of electrons, shown in purple. This model may account for:

• Malleability and Ductility: The sea of electrons surrounding the protons act like a cushion, and so when the metal

is hammered on, for instance, the over all composition of the structure of the metal is not harmed or changed. The

protons may be rearranged but the sea of electrons with adjust to the new formation of protons and keep the metal

intact.

•

Heat

capacity: This is explained by the ability of free electrons to move about the solid.

• Luster: The free electrons can absorb photons in the "sea," so metals are opaque-looking. Electrons on the surface

can bounce back light at the same frequency that the light hits the surface, therefore the metal appears to be shiny.

• Conductivity: Since the electrons are free, if electrons from an outside source were pushed into a metal wire at one

end, the electrons would move through the wire and come out at the other end at the same rate (conductivity is the

movement of charge).

However, these observations are only qualitative, and not quantitative, so they cannot be tested. The "Sea of Electrons"

theory stands today only as an oversimplified model of how metallic bonding works.

Metallic bonding in sodium

Metals tend to have high melting points and boiling points suggesting strong bonds between the atoms. Even a metal like sodium

(melting point 97.8°C) melts at a considerably higher temperature than the element (neon) which precedes it in the Periodic Table.

Metallic Bonding Information Sheet Template