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How many bonds does nitrogen typically form? Does this make sense based on the number of valence electrons in a nitrogen atom? Explain your answer. Does phosphorus typically form the same number of bonds as nitrogen? Use the periodic table to explain why your answer makes sense.
The Correct Answer and Explanation is:
Correct Answer:
Nitrogen typically forms three bonds. This is consistent with the fact that nitrogen has five valence electrons. Phosphorus can form three or five bonds, depending on the compound. This difference makes sense because phosphorus is in period 3 of the periodic table and has access to d-orbitals, while nitrogen is in period 2 and does not.
Explanation:
Nitrogen is an element in group 15 of the periodic table and has five valence electrons. In order to achieve a stable octet, nitrogen tends to form three covalent bonds. This allows nitrogen to share three of its electrons with other atoms and receive three in return, reaching a total of eight electrons in its valence shell. A common example is ammonia (NH₃), where nitrogen forms three single bonds with hydrogen atoms. This bonding behavior is consistent with nitrogen’s electron configuration and its position in period 2, which means it can only use the s and p orbitals for bonding.
Phosphorus, like nitrogen, is also in group 15 and has five valence electrons. However, phosphorus is in period 3, which introduces a key difference. Elements in period 3 and beyond can use their empty d-orbitals for bonding, allowing them to expand their valence shell beyond eight electrons. Because of this, phosphorus is able to form five covalent bonds in certain compounds. A well-known example is phosphorus pentachloride (PCl₅), where phosphorus forms five bonds with chlorine atoms. Despite having the same group number as nitrogen, phosphorus exhibits more flexible bonding due to its larger size and access to more orbitals.
In summary, nitrogen typically forms three bonds, and this fits with its five valence electrons and limited orbital availability. Phosphorus, while also having five valence electrons, can form more bonds due to its ability to expand its valence shell, a feature not available to nitrogen. This difference is explained by their positions on the periodic table.
