Many compounds of group 3 elements have chemical behavior that reflect an electron deficiency.
a) What is the meaning of electron deficiency?
b) Give one reaction that illustrates this behavior.
a) Electron deficiency refers to a situation where an atom or molecule has fewer electrons than the number required to fill its valence shell completely. This results in an imbalance between the positively charged protons in the nucleus and the negatively charged electrons surrounding it, giving rise to unique chemical properties.
b) One reaction that illustrates this behavior is the reaction between boron trifluoride (BF3) and ammonia (NH3) to form a Lewis acid-base adduct:
BF3 + NH3 → F3B-NH3
In this reaction, BF3, a compound of group 3 element boron, acts as a Lewis acid, which is an electron pair acceptor due to its electron deficiency, while NH3 functions as a Lewis base, which is an electron pair donor. The two compounds react to generate a compound that has both coordination or dative covalent bonds due to the electron pair donation by NH3 and electron deficiency of BF3.
a) Electron deficiency refers to a situation where an atom or molecule lacks the sufficient number of electrons to attain a stable electron configuration. It occurs when there are fewer electrons available for bonding or filling the valence shell compared to the number of electrons needed for a stable configuration.
b) One reaction that illustrates the electron deficiency behavior in compounds of group 3 elements is the reaction between boron trifluoride (BF3) and ammonia (NH3) to form boron tris(ammonia) complex, also known as borane-ammonia complex (BH3-NH3):
BF3 + NH3 → BH3-NH3
In this reaction, boron trifluoride (BF3) acts as the electron-deficient compound as it only has 6 valence electrons instead of the desired octet. It accepts a lone pair of electrons from ammonia (NH3) to form a new covalent bond, resulting in the formation of the borane-ammonia complex (BH3-NH3). This reaction demonstrates the electron deficiency of BF3 and its ability to accept electrons from NH3 to achieve a more stable electron configuration.
a) Electron deficiency refers to a situation in which an atom or a group of atoms in a compound has fewer electrons than would be expected based on the octet rule. The octet rule states that most atoms tend to gain, lose, or share electrons in order to achieve a stable electron configuration with a full outer shell of eight electrons. In the case of compounds of group 3 elements, such as boron, aluminum, or gallium, these elements have valence shells with fewer than eight electrons. This results in a relative lack of electrons and creates a chemical behavior that is characteristic of electron-deficient compounds.
b) One reaction that illustrates the electron-deficient behavior of group 3 elements is their reaction with Lewis bases, which are electron donors. For example, let's consider the reaction between boron trifluoride (BF3) and ammonia (NH3).
BF3 is a compound of boron, which is a group 3 element. It has three valence electrons, leaving it with an electron deficiency. Ammonia is a Lewis base that has a lone pair of electrons on the nitrogen atom.
The reaction can be represented as follows:
BF3 + NH3 → BF3NH3
In this reaction, the electron-deficient boron in BF3 acts as a Lewis acid, and the lone pair of electrons on the nitrogen atom in NH3 acts as a Lewis base. The Lewis base donates its lone pair of electrons to the electron-deficient boron atom, resulting in the formation of a coordinate covalent bond. This reaction illustrates the behavior of group 3 elements to accept electron pairs to satisfy their electron deficiency.