Question

Which of the following statements is false? (1) Beryllium forms covalent compounds due to small size and high charge of the ${\mathrm{Be}}^{2+}$ ion. (2) The maximum coordination number of beryllium is $\mathbf{s}\mathbf{i}\mathbf{x}$. (3) Beryllium salts are extensively hydrolyzed. (4) Beryllium can form complexes due to its small size.

Short answer

Statement 2 is false.

Step-by-step solution

Analyze Statement 1

Statement 1: Beryllium forms covalent compounds due to small size and high charge of the ${\mathrm{Be}}^{2+}$ ion.Beryllium has a high charge density, leading to the formation of covalent compounds. This statement is true.

Analyze Statement 2

Statement 2: The maximum coordination number of beryllium is six.Beryllium, due to its small size, typically has a maximum coordination number of four, not six. This statement is false.

Analyze Statement 3

Statement 3: Beryllium salts are extensively hydrolyzed.Beryllium salts undergo hydrolysis due to the high polarizing power of ${\mathrm{Be}}^{2+}$. This statement is true.

Analyze Statement 4

Statement 4: Beryllium can form complexes due to its small size.Beryllium's small size allows it to accept electrons and form complexes. This statement is true.

Key concepts

covalent compounds

Beryllium (Be) forms covalent compounds mainly because of its small size and high charge density. When we compare Be to other elements, its ion ${\mathrm{Be}}^{2+}$ has a very high charge relative to its size. This high charge density attracts electron clouds from other atoms very strongly, leading to the formation of covalent bonds.
The attraction between ${\mathrm{Be}}^{2+}$ and electrons is so strong due to the significant charge concentration in such a small area. This makes it more favorable for beryllium to share electrons rather than participate in ionic bonding, thus forming covalent compounds.
In simpler terms, beryllium prefers to share electrons with other atoms because it holds onto its electrons very tightly, preventing easy transfer as seen in ionic bonds.

coordination number

The coordination number of an element refers to the number of atoms or ions directly bonded to it. For beryllium, this number is typically four. Beryllium's small atomic size restricts the number of atoms that can surround it. As it only forms small-sized ions, it doesn’t have enough space around each ion to accommodate more than four ligands or atoms.
Statements suggesting that beryllium can achieve a coordination number of six are therefore incorrect.
Unlike larger elements like iodine or xenon which can accommodate many more ligands due to their larger size, beryllium's coordination capacity is limited by its compact atomic structure.

hydrolysis

Hydrolysis refers to the chemical process where ions react with water, leading to the formation of weak acids or bases. Beryllium salts undergo extensive hydrolysis due to the high polarizing power of the ${\mathrm{Be}}^{2+}$ ion. This high polarizing power disrupts the hydrogen-oxygen bonds in water molecules more efficiently.
Consequently, ${\mathrm{Be}}^{2+}$ hydrolyzes to form beryllium hydroxide and either hydronium ions or other products depending on the specific reaction conditions. This makes beryllium salts behave differently compared to salts of other metals, often resulting in solutions that are more acidic due to the release of ${\mathrm{H}}^{+}$ ions.

complex formation

In chemistry, a complex forms when a central metal atom or ion, is surrounded by molecules or ions containing lone pairs of electrons that coordinate to the metal. Beryllium forms complexes due to its small size and ability to accept electron pairs easily.
For instance, in a complex like ${\mathrm{BeF}}_4^{2-}$, beryllium accepts pairs of electrons from four fluoride ions. Its small size and high charge density make it effective at pulling in electron pairs and holding them tightly.
This ability to form complexes has significant implications in various fields including material science, biology, and industrial chemistry where beryllium's unique properties are utilized in special applications.