Question

Which atoms are likely to form stable molecules that have an incomplete octet on the central atom?

[Select all that apply.]
a. B
b. P
c. Be
d. H
e. C
f. F
d. Si

Answer 1

Boron (B) and beryllium (Be) are likely to form stable molecules with an incomplete octet on the central atom, as seen in BeH2 and BF3, despite being electron-deficient.

Step-by-step explanation:

Atoms that are likely to form stable molecules with an incomplete octet on the central atom include boron (B) and beryllium (Be). These elements are known for forming electron-deficient molecules, typically due to their position in groups 2 and 13 of the periodic table. For instance, in beryllium dihydride (BeH2) and boron trifluoride (BF3), the central beryllium and boron atoms do not have a full octet of electrons, with beryllium having only four and boron having six. Despite their incomplete octets, these molecules are stable due to their bonding characteristics and experimental evidence that indicates a suitable Lewis structure with electron-deficient bonding situations.

Boron and aluminum, with three valence electrons, tend to form covalent compounds with an incomplete octet. The central boron atom in boron trichloride (BCl3) has six valence electrons.

Beryllium, from group 2, also forms covalent compounds with an incomplete octet. For example, the Lewis structure of gaseous beryllium hydride (BeH2) consists of two single covalent bonds between Be and H.

The most common examples of stable compounds with an incomplete octet are covalent compounds of beryllium and boron, such as BeH2 and BCl3.