Question

Beryllium shows some covalent characteristics in some of its compounds, unlike the other alkaline earth compounds. Give a possible explanation for this phenomenon.

Short answer

Beryllium's small size and a high charge density for its +2 ion (Be^2+) cause it to attract its own electrons and the electrons of neighboring atoms more strongly. This increased electron attraction is responsible for the covalent characteristics observed in some of its compounds, unlike the ionic nature observed in other alkaline earth metals.

Step-by-step solution

Identify the position of Beryllium in the periodic table

Beryllium is an element with the atomic number 4 and is located in the second column (Group 2) and second row (Period 2) of the periodic table. It is a member of the alkaline earth metals, along with magnesium, calcium, strontium, barium, and radium.

Compare Beryllium's properties with other alkaline earth metals

Beryllium is unique among the alkaline earth metals because it is much smaller than the other elements in its group. This is because its only first two main energy levels (1s and 2s) are filled with electrons, whereas other Group 2 elements have more energy levels. Beryllium has only four electrons, with two in the 1s energy level and a valence shell configuration of 2s^2.

Understand how its size affects its properties

Beryllium's small size and a high charge density for its +2 ion (Be^2+) cause it to attract its own electrons and the electrons of neighboring atoms more strongly. This increased electron attraction is responsible for the covalent characteristics observed in some of its compounds.

Explain the covalent characteristics exhibited by Beryllium

Due to Beryllium's small size and a high charge density of Be^2+, its ion attracts the electron cloud of the bonded anions. Consequently, the electrons in the bond are shared between Beryllium and the other atom instead of being fully transferred. This results in a partial covalent character in the bonding with other atoms, making Beryllium different from other alkaline earth metals, which are typically ionic in nature.