Question

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

Short answer

The answer is option (c) 3,5.

Step-by-step solution

Understanding Covalent Bonds

Covalent bonds form when atoms share pairs of electrons. The ability to form covalent bonds is related to the number of valence electrons an atom has and its need to achieve a stable electron configuration.

Nitrogen's Covalent Bonding

Nitrogen (139 ) has five valence electrons. To achieve a stable octet configuration, it needs three additional electrons, which it can share with other atoms. Therefore, nitrogen typically forms three covalent bonds, as seen in molecules like ammonia (139 H3 ).

Phosphorus's Covalent Bonding

Phosphorus (139 P ) also has five valence electrons similar to nitrogen, but it belongs to the third period of the periodic table. This allows it to use d-orbitals to expand its valence shell and form additional bonds. Phosphorus is thus capable of forming up to five covalent bonds, as seen in phosphorus pentachloride (PCl5 ).

Combining Information

Now that we have determined the maximum number of covalent bonds formed by nitrogen and phosphorus, we compare these findings to the given options. Nitrogen can form 3 bonds, and phosphorus can form 5 bonds.

Key concepts

Valence Electrons

Valence electrons are the outermost electrons of an atom that are involved in forming chemical bonds. They play a crucial role in determining an element's chemical properties, including its reactivity and the type of bonds it can form. In the context of covalent bonding, atoms tend to share valence electrons to achieve a stable electron configuration, typically resembling that of the nearest noble gas in the periodic table.
For example, nitrogen has five valence electrons. This means it needs three more electrons to complete its valence shell and reach the stable octet configuration. In covalent bonding, nitrogen can share three of its valence electrons with other atoms, forming three covalent bonds in substances like ammonia ( H_3 ).
Phosphorus, like nitrogen, also has five valence electrons. However, thanks to its place in the third period of the periodic table, it can utilize d-orbitals to expand its valence shell. This allows phosphorus to form more complex structures by involving additional bonds. Phosphorus can form up to five covalent bonds, as seen in phosphorus pentachloride ( PCl_5 ).

• Valence electrons are key to bond formation.
• They determine an atom’s ability to achieve a stable configuration.

Electron Configuration

Electron configuration describes the arrangement of electrons within an atom's orbitals. This configuration is crucial for understanding how atoms interact and bond with one another. Each element has a unique electron configuration that influences its position in the periodic table and its chemical properties.
For instance, the electron configuration of nitrogen is 1s² 2s² 2p³. The configuration shows that nitrogen has five electrons in its outermost shell, which are its valence electrons. The half-filled p orbitals make nitrogen highly reactive and capable of forming three covalent bonds.
Phosphorus, with an electron configuration of 1s² 2s² 2p⁶ 3s² 3p³, also has five valence electrons. However, phosphorus belongs to a period where additional orbitals (d-orbitals) are available once the outer shell is filled. This allows it to expand its bonding capacity beyond what is usual in the second period, enabling the formation of up to five covalent bonds.

• Shows how electrons fill orbitals.
• Helps predict bonding behavior and stability.

Periodic Table

The periodic table is a comprehensive chart organizing elements based on their atomic number, electron configuration, and recurring chemical properties. It is an essential tool in chemistry for predicting the behavior of elements and their compounds.
Elements are arranged in periods (rows) and groups (columns), which correlate with their electron configuration and, consequently, their chemical properties. Elements in the same group, like nitrogen and phosphorus, typically exhibit similar behavior because they have the same number of valence electrons.
Nitrogen, located in the 15th group and second period, has five valence electrons and typically forms three covalent bonds due to its limited electron capacity. Phosphorus, also in group 15 but in the third period, can exceed these constraints by utilizing available d-orbitals in its valence shell, forming up to five covalent bonds.

• Organizes elements by shared properties.
• Helps predict reactivity and bonding patterns.