Maximum number of covalent bonds formed by \(\mathrm{N}\) and \(\mathrm{P}\) respectively are: (a) 3,6 (b) 4,6 (c) 3,5 (d) 4,5

Valence electrons are the outermost electrons of an atom and play a crucial role in chemical bonding and stability. In the context of covalent bonding, valence electrons are shared between atoms to form a bond. For example, each nitrogen atom (N) has five valence electrons, as it is in group 15 of the periodic table. When two nitrogen atoms bond, they share three pairs of electrons to acquire a stable structure, resulting in the formation of a nitrogen molecule (N₂).

Due to valence electrons, elements are able to interact and link with others to form molecules. The number of valence electrons also determines the chemical reactivity and bonding capacity of an element. As a rule of thumb, elements with a complete set of valence electrons tend to be inert or less chemically reactive.

The octet rule is a fundamental concept in chemistry that states that atoms tend to bond in such a way that they have eight electrons in their valence shell. This desire to fill or empty their valence shell to achieve a noble gas configuration is what drives chemical bonding. Nitrogen, for instance, with its five valence electrons, seeks to share three electrons with other atoms to satisfy the octet rule, leading to the formation of three covalent bonds.

It's important to understand, however, that not all elements follow the octet rule strictly. Transition metals and larger elements, like phosphorus (P), can expand their shell capacity to accommodate more than eight electrons. The ability of atoms like phosphorus to form more than three covalent bonds is a concept known as the expanded octet, which is applicable in certain circumstances, particularly for elements in the third period and beyond of the periodic table.

The periodic table is categorized into 18 vertical columns known as groups or families. Elements in the same group typically exhibit similar chemical properties and have the same number of valence electrons, which plays a significant role in their bonding behavior. Group 15, for instance, includes the pnictogens like nitrogen (N) and phosphorus (P), each with five valence electrons. This similarity explains why both can form three covalent bonds by sharing three electrons.

Understanding periodic table groups offers insight into the tendencies of elements to form certain compounds. Furthermore, recognizing the group an element belongs to can quickly inform us about its reactivity, the types of bonds it will form, and how many covalent bonds it is capable of forming, simplifying the predictions about the behavior of elements in chemical reactions.