Tag: chemical bonding and structure

In contrast to electrons that participate in both ionic and covalent bonds, electrons that participate in metallic bonds delocalize, forming a sea of electrons around the positive nuclei of metals. The availability of "free" electrons contributes to metals being excellent conductors.

Metals (metallic bonds) have these physical properties- 

Many of the characteristic properties of metals are attributable to the non-localized or free-electron character of the valence electrons. This condition, for example, is responsible for the high electrical conductivity of metals. The valence electrons are always free to move when an electrical field is applied. The presence of the mobile valence electrons, as well as the nondirectionality of the binding force between metal ions, account for the malleability and ductility of most metals. When a metal is shaped or drawn, it does not fracture, because the ions in its crystal structure are quite easily displaced with respect to one another. Moreover, the nonlocalized valence electrons act as a buffer between the ions of like charge and thereby prevent them from coming together and generating strong repulsive forces that can cause the crystal to fracture.
Hence option D is correct.

A cation is formed when a metal ion loses a valence electron so as to achieve a more stable electronic configuration through this loss of an electron.

Electron Pool Theory. 

Metallic bonding arises from the electrostatic attractive force between conduction electrons (in the form of an electron cloud of delocalized electrons) and positively charged metal ions. It may be described as the sharing of free electrons among a lattice of positively charged ions (cations). 

Metallic bonding may be described as the sharing of free electrons among a lattice of positively charged metal ions. The structure of metallic bonds is very different from that of covalent and ionic bonds. While ionic bonds join metals to nonmetals, and covalent bonds join nonmetals to nonmetals, metallic bonds are responsible for the bonding between metal atoms. In metallic bonds, the valence electrons from the s and p orbitals of the interacting metal atoms delocalize. That is to say, instead of orbiting their respective metal atoms, they form a sea of electrons that surrounds the positively charged atomic nuclei of the interacting metal ions. The electrons then move freely throughout the space between the atomic nuclei.

In a metallic bond, electrons are shared with more than one atoms. Due to this, the valance electrons are spread all over the crystal. Hence, metallic bonds are non-directional.

Metallic bonding is the strong attraction between closely packed positive metal ions and a 'sea' of delocalised electrons. So,high energy is required to overcome this bond, hence high temperature can be used to weaken or overcome these attractive forces.