A coordinate covalent bond is one formed by sharing a pair of electrons provided by one of the two bonded atoms. The atom that provides two electrons to form a coordinate bond is known as the donor, and the atom that receives the pair of electrons from the donor is known as the acceptor. A coordinate bond is represented by an arrow pointing from the donor to the acceptor, with a positive charge on the donor and a negative charge on the acceptor.
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Definition: A coordinate bond is a type of covalent bond (a shared pair of electrons) in which both electrons are derived from the same atom. |
Coordinate Bond Chemistry Questions with Solutions
Q-1: Which of the following molecules does not have coordinate bonds?
a) CH3-NC
b) CO
c) O3
d) CO32-
Answer: d) CO32-
Q-2: Which types of bonds are present in N2O5?
a) only coordinate
b) only ionic
c) coordinate and ionic
d) covalent and coordinate
Answer: d) covalent and coordinate
Q-3: Which of the following occurs during the formation of a coordinate bond?
a) Electron transfer
b) Electron donation
c) Electron sharing
d) equal electron transfer between bonded atoms
Answer: b) Electron donation
Explanation: When a donor atom donates its pair of electrons to the acceptor atom, a coordinate bond is formed. Electron donation occurs as a result.
Q-4: When NH3 and BF3 form a covalent coordinate bond, electron donation occurs in
- 2p-orbital of N-atom
- 2p-orbital of B-atom
- 1s-orbital of H-atom
- 2p-orbital of F-atom
Answer: b) 2p-orbital of B-atom
Explanation: Boron has an empty 2p-orbital, while nitrogen has a single electron pair. Nitrogen donates its pair of electrons to the empty 2p orbital of boron.
Q-5: Coordinate bond is also known as
a) Native bond
b) Dative bond
c) Polar covalent bond
d) Electrovalent bond
Answer: b) Dative bond
Q-6: How is the pi- coordinate bond formed? Explain with an example
Answer: Pi-coordinate bonds are typically formed in compounds with back bonding. It is formed by electrons being donated from the donor atom to the atom that requires electrons. As an example: Boron has an empty p-orbital in BF3, while fluorine has a lone pair of electrons. As a result, fluorine donates its lone pair of electrons to the Boron atom, thereby satisfying its deficiency.
Q-7: Mention the type of 𝞹-coordinate bond in each of the following:
1) N(SiH3)3
2) BF3
3) BCl3
4) H3Si-N=C=S
5) OCl2
Answer:
|
Compound |
Direction of donation |
Type of 𝞹-coordinate bond |
|---|---|---|
|
N(SiH3)3 |
2p of N to 3d of Si |
2p𝞹-3d𝞹 |
|
BF3 |
2p of F to 2p of B |
2p𝞹-2p𝞹 |
|
BCl3 |
3p of Cl to 2p of B |
2p𝞹-3p𝞹 |
|
H3Si-N=C=S |
2p of N to 3d of Si |
2p𝞹-3d𝞹 |
|
OCl2 |
2p of O to 3d of Cl |
2p𝞹-3d𝞹 |
Q-8: How many dative bonds do sodium isocyanide and sodium cyanide have?
Answer: The formula for sodium isocyanide is NaNC, which has only one dative bond. Sodium cyanide, on the other hand, is NaCN, which has no dative bonds.
Q-9: Is it possible for a coordinate bond to be a sigma bond?
Answer: Yes, a coordinate bond is similar to a regular covalent bond, except that both electrons in the bond come from the same atom. A single coordinate bond is, therefore, a sigma bond..
Q-10: Match the column I with column II
|
Column I |
Column II |
|---|---|
|
a) H+ + H2O |
1) Covalent bond |
|
b) I + I |
2) Coordinate bond |
|
c) Na + ½ Cl2 |
3) Polar covalent bond |
|
d) H2+I2 |
4) Ionic bond |
Answers: a)-2, b)-1, c)-4), d)-3
Q-11: A coordinate bond is formed in a molecule when an atom
a) has an electric charge
b) has all of its valence electrons shared
c) has only one unshared electron
d) has one or more unshared electron pairs.
Answer: d) has one or more unshared electron pairs
Q-12: Why is N(SiH3)3 planar but (SiH3)3P pyramidal?
Answer: When electron pairs are donated from the central atom to a side atom, hybridisation always decreases by one step. In N(SiH3)3, electron donation takes place from 2p of N-atom to 3d of Si atom. As a result of the formation of the 2p(N)𝞹-3d(Si)𝞹 coordinate bond, N(SiH3)3 is planar and not pyramidal.
On the other hand, in (SiH3)3P there is no such coordinate bond formation, therefore hybridization remains unaffected.
Q-13: When two species, X and Y, form an electron-pair bond but X does not contribute electrons to the bond. What information can be predicted about the X-Y bond?
Answer: Because Y contributes electrons to the bond formation, the bond formed between X and Y is covalent. Because one atom is donating electrons, it is also coordinate. The bond is thus a coordinate covalent bond.
Q-14: In coordination compounds, a coordinate covalent bond is formed between what kind of particles?
a) A ligand and counter ion
b) Metal and ligand
c) Counter ion and metal
d) between ligands
Answer: b) Metal and ligand
Explanation: Ligands are electron donor species that donate electrons to metal ions through the formation of coordinate covalent bonds.
Q-15: Explain the formation of a coordinate bond in the CO molecule.
Answer: A covalent coordinate bond is formed between carbon and oxygen in a CO molecule. The oxygen atom donates one of its unshared electron pairs to carbon, allowing both carbon and oxygen to have a stable configuration.
Practise Questions on Coordinate Bond
Q-1: In a coordinate bond
a) Electrons are transferred between bonded atoms
b) Electrons are equally shared between bonded atoms
c) Electrons are shared only by one atom
d) Electrons are donated by both the atoms
Q-2: What type of bond exists between B and O in (C2H5)2OBH3?
a) Banana bond
b) Hydrogen bond
c) Ionic bond
d) Dative bond
Q-3: Which of the following species contain a coordinate bond?
a) FeCl3
b) CO
c) [Fe(CN)5NO]2-
d) N3–
Q-4: What are the conditions required for the formation of 𝞹-coordinate bond?
Q-5: Why is the Lewis acidity of BF3 lower than that of BCl3, despite the fact that fluorine is more electronegative than chlorine?
Click the PDF to check the answers for Practice Questions.
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