Octet Rule and its Exceptions Quiz

Expanded octets are molecules that have more than 8 electrons surrounding the central atom. In these molecules, the central atom can accommodate additional electrons in its valence shell by using its empty d orbitals, allowing for the formation of more than the usual 8 electron pairs. This phenomenon is commonly observed in elements from the third period onwards, such as sulfur, phosphorus, and chlorine. The expanded octet allows these elements to achieve a more stable electron configuration and form more bonds, increasing their bonding capacity and overall reactivity.

Molecules with less than 8 electrons surrounding the central atom have incomplete octets. This means that the central atom does not have a full valence shell of electrons, which is typically 8 electrons for most atoms. This can occur when the central atom forms bonds with other atoms, resulting in fewer than 8 electrons in its valence shell.

Calcium (Ca) is an element with atomic number 20. It has 20 protons and 20 electrons. To become stable, it needs to achieve a full outer electron shell, which can be achieved by losing 2 electrons. This will result in a stable electron configuration similar to the noble gas argon (Ar) with 18 electrons in its outer shell.

Magnesium is the correct answer because it has two valence electrons in its outermost energy level. By losing these two electrons, magnesium achieves a stable octet configuration, similar to the noble gas neon. This electron loss allows magnesium to attain a full outer shell, making it more stable and less reactive.

Potassium is the correct answer because it is an alkali metal with one valence electron in its outermost shell. In order to attain a stable octet, it loses this electron, resulting in a full outer shell with eight electrons. This loss of one electron allows potassium to achieve a stable electron configuration, making it more stable and less reactive.

All of these are exceptions to the octet rule. The octet rule states that atoms tend to gain, lose, or share electrons in order to achieve a stable configuration with eight valence electrons. However, there are certain cases where atoms can have more or less than eight electrons in their valence shell. Expended octet refers to elements that can accommodate more than eight electrons in their valence shell, such as elements from the third period onwards. Incomplete octet refers to elements that have fewer than eight electrons in their valence shell, such as hydrogen and helium. Odd number octet refers to elements that have an odd number of valence electrons, such as nitrogen. Therefore, all of these options deviate from the octet rule.

A molecule with unpaired electrons surrounding the central atom is classified as having odd number electron. This means that the total number of electrons in the molecule is an odd number, with at least one electron being unpaired. This type of molecule is often referred to as a free radical, as the unpaired electron makes it highly reactive and prone to forming chemical bonds with other molecules in order to stabilize itself.

Boron has too few electrons to form an octet. In its ground state, it has only three valence electrons. In order to achieve a stable electron configuration, it tends to lose or share electrons rather than gain the necessary five electrons to complete its octet. Therefore, boron is unable to form an octet. Carbon dioxide and oxygen, on the other hand, can both form octets by gaining or sharing electrons. The option "None of these" is incorrect as boron does not have enough electrons to form an octet.

The octet rule is an important chemical rule of thumb that states that atoms that have bonded share eight outer electrons. This rule helps in understanding the stability and reactivity of atoms and molecules. Both statements A and B are true, as they accurately describe the octet rule and its significance in chemistry.

Both hydrogen and beryllium have too few electrons to form an octet. An octet refers to having eight valence electrons in the outermost energy level. Hydrogen has only one electron, while beryllium has only two electrons. Therefore, neither of these elements can achieve a stable electron configuration by forming an octet.