A Level Chemistry Revision "Dative Covalent Bonding".

Summary

In this educational video on dative covalent bonds, the host explains their formation using the example of ammonia and the hydrogen ion. The nitrogen atom, possessing a lone pair of electrons, can create a dative bond with the hydrogen ion, resulting in the ammonium ion (NH4+). Key points include the electron deficiency of the acceptor atom and that dative bonds are equivalent to normal covalent bonds in terms of strength and length. The video also briefly touches on another example involving ammonia and boron trifluoride, highlighting the role of electron deficiency in bond formation.

Takeaways

• 😀 A dative covalent bond, also known as a coordinate bond, is formed when an atom uses a lone pair of electrons to bond with another atom.
• 😀 The nitrogen atom in ammonia (NH3) has five electrons in its outer shell and forms three covalent bonds with hydrogen atoms.
• 😀 The lone pair of electrons on the nitrogen atom allows it to bond with an electron-deficient species, such as a hydrogen ion (H+).
• 😀 When ammonia reacts with H+, it forms the ammonium ion (NH4+), demonstrating the formation of a dative covalent bond.
• 😀 In a displayed formula, a dative bond is represented by an arrow pointing from the atom providing the lone pair to the atom accepting it.
• 😀 For a dative bond to form, the acceptor atom must be electron-deficient and have available orbitals for electrons.
• 😀 A dative covalent bond is identical to a normal covalent bond in terms of bond length and average bond enthalpy.
• 😀 The average bond enthalpy indicates the strength of a bond, showing that dative bonds have the same strength as other covalent bonds in a molecule.
• 😀 Another example of a dative covalent bond is the reaction between ammonia and boron trifluoride (BF3), where boron is electron-deficient.
• 😀 The next topic in the series will cover the shapes of molecules, building on the understanding of covalent bonding.

Q & A

What is a dative covalent bond?

A dative covalent bond, also known as a coordinate bond, is formed when one atom donates a pair of electrons to another atom that is electron deficient.

How does ammonia demonstrate the formation of a dative bond?

In ammonia (NH₃), the nitrogen atom, which has a lone pair of electrons, can donate this pair to a hydrogen ion (H⁺), resulting in the formation of the ammonium ion (NH₄⁺).

What is the role of the lone pair of electrons in dative bonding?

The lone pair of electrons from the donor atom is used to form a bond with the electron-deficient atom, allowing for the creation of a dative covalent bond.

What does it mean for an atom to be electron deficient?

An electron-deficient atom has fewer than eight electrons in its outer shell, making it capable of accepting electrons from another atom to complete its valence shell.

How are dative bonds represented in chemical structures?

Dative bonds are represented with an arrow in chemical structures, where the arrow points from the atom donating the lone pair to the atom accepting it.

Do dative covalent bonds have different properties than normal covalent bonds?

No, dative covalent bonds are identical in strength and length to normal covalent bonds, meaning they have the same bond enthalpy and bond characteristics.

What is the significance of average bond enthalpy in the context of dative bonds?

Average bond enthalpy indicates the strength of a bond; in the ammonium ion, the dative bond has the same bond strength as the other covalent bonds present.

Can you provide another example of a dative bond formation?

Another example is the reaction between ammonia and boron trifluoride (BF₃), where the nitrogen atom in ammonia forms a dative bond with the electron-deficient boron atom.

What is the displayed formula of the ammonium ion?

The displayed formula of the ammonium ion (NH₄⁺) shows the dative bond with an arrow pointing from the nitrogen atom to the hydrogen ion (H⁺).

What topic is planned for the next video in the series?

The next video will cover the shapes of molecules, building on the concepts introduced in this video.