Nitrogen is a gas at room temperature while phosphorous is a solid .Explain
Answers
The size of nitrogen is quite small. As a result two nitrogen atoms can be linked to each other by three covalent bonds in order to complete the octets of both the nitrogen atoms. This diatomic molecule N2 is very stable and has very negligible attraction towards other diatomic nitrogen molecules. Thus there is weak interaction between nitrogen molecules. So nitrogen exist as gas.
While phosphorus being large in size has less tendency to form three bonds. Therefore, P atoms completes octets by sharing its valence electrons with three other P atoms. As a result, it exist as tetratomic P4 molecule. In white phosphorous there is network which holds the phosphorous atoms together. This catenation tendency of phosphorus is reason why it exist as solid.
Answer:
When we think about which simple phase (solid/liquid/gas) a chemical species will be in, we think about their melting point and boiling point. What mainly determines these physical properties is the type of electronic interactive forces between molecules. The stronger the force, the higher its melting and boiling point.
If we expect the forces to be similar in nitrogen, phosphorus, oxygen, chlorine etc., then what other possible factors might we be able to turn to? The key factor is “molecules”: phosphorus’ molecule structure is different. Phosphorus, like its fellow elements such as silicon, sulfur, and carbon, favourably form allotropes (giant unit structures) which give them much higher surface for the interactive forces between each units; thus, they tend to exist as solids rather than gas. Phosphorus allotropes can be in units of 4 P atoms and form different kinds of giant extensive structures, On the other hand, the elements nitrogen, oxygen and chlorine favourably exist as diatomic molecules, and they cannot form giant structures due to their bonding limits. Only under harsh conditions will Phosphorus form a diatomic gas .