Test: Chemical Bonding- 1

LiF (Lithium Fluoride) is an example of Ionic bond, as the formation takes place by transfer of electrons and not by sharing.

This is because they have the tendency to transfer electrons.

Both Ionic and Covalent bond arise from the tendency of atoms to attain stable configuration of electrons.

As we know that ionic bond is formed between an electropositive and an electronegative atom and covalent bond is formed between two electronegative or electropositive elements. In all above options NO3 the bonds are ionic in nature but NO3 is covalent in nature as bond is formed between two electronegative atoms i.e. N and O.

Carbonium ion methonium,  CH5+ is produced by the addition of  H+ to CH4. In CH5+ three hydrogen atoms are in a plane and one above and one below the plane. 

So its sp3d and the shape is trigonal bipyramid. 

But this compound is considered a CH3+ carbenium ion with a molecule of hydrogen interacting with the empty orbital in a 3-center-2-electron bond. As the two hydrogen atoms in H2 are in continuously exchange positions with the three hydrogen atoms in the CH3+ methonium  CH5+ is considered as a fluxional molecule. Due to the existence of CH3+ this is sp​2 hybridised. 

Both Ionic and Covalent bond arise from the tendency of atoms to attain stable configuration of electrons.

Correct Answer :- C

Explanation : BF3 has a boron atom with three outer-shell electrons in its ground state and three fluorine atoms containing seven outer electrons. Further, if we observe closely, one boron electron is unpaired in the ground state. During the formation of this compound, the 2s orbital and two 2p orbitals hybridize. Only one of the empty p-orbital is left behind as the lone pair. In short, Boron needs 3 hybridized orbitals to make bonds with 3 atoms of F where the 2pz orbitals get overlapped with these hybridized sp2 orbitals and bonds are formed.

Ionic bond results from a), b) and d). But the transfer of electrons is a property of Covalent bond.

An allene is a compound in which one carbon atom has double bonds with each of its two adjacent carbon centres.

The central carbon atom of allene forms two sigma bonds and two pi bonds. The central carbon is sp-hybridized, and the two terminal carbon atoms are sp²-hybridized. The bond angle formed by the three carbon atoms is 180°, indicating linear geometry for the carbon atoms of allene.

A hypervalent molecule (the phenomenon is sometimes colloquially known as expanded octet) is a molecule that contains one or more main group elements apparently bearing more than eight electrons in their valence shells.