Nitrogen

Liquid nitrogen freezes at -346 °F (-210 °C, 63 K).

I think the bonding is covalent as it is between two non-metals

rhizobium, frankia, azospirlium, azotobacter

Most plants use single nitrogen atoms, not N2 molecules.

There are two types of bacteria; nitrifying bacteria and denitrifying bacteria. The work of denitrifying bacteria such as Thiobacillus and Micrococcus is converting nitrates to nitrogen that is released to the atmosphere.

Nitrogen is a major component in air making up 78% of the volume of the gases we breathe every day. It is, however, not able to support life, so if it is the only thing being inhaled, the human will die within a few minutes. They would essentially suffocate.

Transpiration

The major elements cycled in nature are carbon, nitrogen, phosphorus, and sulfur, and oxygen which forms part of all the cycles.

Nitrifying bacteria can convert atmospheric nitrogen in to nitrates that plants can use in the soil. That is why leguminous plants having these micro-organisms in the nodules enrich the soil for nitrogen deficiency.

All organisms need nitrogen to live and grow. Plants take up nitrate ions from the soil, they are then absorbed into roots by active transport, the plant then produces nitrogen-containing compounds such as protein. This nitrogen then gets into the food web as primary consumers feed on plants and obtain the nitrogen-containing compounds. However, the atmosphere is made up of 78% nitrogen and is unavailable in this form to organisms. This is due to the triple bond between the two N atoms causing it to be inert. To be used by organisms, it must be converted to a chemically available form, such as ammonium (NH4+), nitrate (NO3-), or urea ((NH3)2CO). There are five main processes that convert nitrogen to a more accessible form. They are; nitrogen fixation, nitrogen uptake, decay process, nitrification and denitrification. The first process I will talk about is nitrogen fixation. There, the nitrogen is converted to ammonium; it is the only way organisms can obtain nitrogen directly from the atmosphere. The only organism that can fix nitrogen through metabolic process is bacteria from the genus Rhizobium. The nitrogen fixers are usually found on host plants, but there are also nitrogen fixing bacteria found without host plants. They are known as free-living nitrogen fixers, e.g. in the aquatic environment a very important nitrogen fixer would be cyanobacteria. Nitrogen fixation can also be carried out in high-energy natural events, such as lightning and forest fires. The high-energy breaks the triple bond between the two nitrogen atoms producing a significant amount of single nitrogen atoms available for use. The next process is nitrogen uptake, this is where plants or bacteria itself makes use of the ammonia produced by the nitrogen fixing bacteria. The ammonium is converted from NH4+ to N to make protein or other nitrogen containing compounds. A very important process that returns nitrogen back to the nitrogen cycle for use is the decay process. When organisms, die, nitrogen is converted back into inorganic nitrogen by a process called nitrogen mineralization. Decomposers consume the organic matter and this leads to decomposition. Nitrogen contained within the dead organism in converted to ammonium, it is then available for use to plants, or transformed into NO3- (nitrification). Through the nitrogen cycle, food-making organisms obtain necessary nitrogen through nitrogen fixation and nitrification. Nitrogen compounds are returned to atmosphere and soil through decay and denitrification. In crops, few plants are left to decay back into soil, so the nitrogen cycle doesn't supply enough nitrogen to support plant growth. Therefore natural or artificial fertilizers containing NO3- or NH4+ compounds are added.

It is called Nitrification. Some bacteria and lightning does that

The simplest answer is that none of the oxygens in N2O5 have a -2 formal charge, so giving nitrogen a +5 formal charge would lead to a charge imbalance. Since the molecule must be charge neutral, we know that the nitrogen must have a different formal charge. (Proof by Contradiction)

The more complicated answer requires a discussion of the bonding in N2O5. As explained in the video in the Related Link, each of the nitrogens sits touching three oxygens, with one of these three being shared with the other nitrogen. The "middle" oxygen is single-bonded to each nitrogen, meaning that the oxygen in question has a 0 formal charge. On the extremities, there are two oxygens that are single-bonded to a nitrogen and two oxygens that are double-bonded. The single-bonded ones have a -1 formal charge and the double bonded ones have a 0 formal charge. This makes the total formal charge coming from the five oxygens to be 0+0-1-1+0 = -2. Therefore the nitrogens must each be +1 since the structure is parallel and the charge must be neutral.

Oh dear what a strange question. In simple classical pre- GN Lewis octet rule following the definition of valency the valency of N is 5. two double bonds one single surrounding each N. (this old theory would give 10 valence electrons around the N) From an oxidation number point of view (sometimes termed valency these days) the N atoms oxidation #'s are +5. However if you apply the octet rule you get a different answer , involving charged structures which in valence bond theory resonate. This is I think what the answer above is getting at.

Yes, liquid nitrogen can cause a rash or skin irritation due to its extremely low temperature, which can lead to frostbite or cryogenic burns upon contact with skin. This can result in redness, blistering, and peeling of the skin. Proper protective equipment should be worn when handling liquid nitrogen to prevent such injuries. If skin contact occurs, it is important to seek medical attention.

Yes, soil does contain nitrogen.

Precautions:

- When opening nitrogen cylinders or pipelines lines, insure that you are in a well ventilated space. Bleed off pressure slowly. A confined space with nitrogen present is a killer.

- Avoid directly breathing nitrogen, when using it. A respirator will not save you if the percentage of nitrogen in the atmosphere increases to 90%, displacing oxygen down to around 11%. Only a self-contained breathing apparatus can be used in this type of atmosphere. The results of overexposure to nitrogen can be sudden and immediate. If oxygen the level fall below 18%, seek a safe environment immediately.

- If a co-worker has been overcome with nitrogen in a confined space, DO NOT rush in unprotected to try to rescue. Immediately call 911, then put on an SCBA, to attempt rescue of the person.

- Always test confined space atmospheres and continuously monitor it if compressed nitrogen gas is being used in that atmosphere for purging.

- NEVER open a vessel that is under a nitrogen purge to look into it, without first having a SCBA on and operating. The effects of nitrogen poisoning to the body is immediate, and workers have been known to lose consciousness and fall into vessels that were open under a nitrogen purge.

- Shut off all cylinders and nitrogen supply tanks when finished with use. Properly secure cylinders and tanks to a non-moveable structure. All empty and full containers should be labeled.

At the same pressure yes, liquid nitrogen is colder than gaseous nitrogen.

Nitrogen does not bind to hemoglobin in the way that oxygen does. Hemoglobin specifically binds to oxygen molecules for transport in the bloodstream. While nitrogen is present in the air we breathe, it is mostly inert and does not participate in the same biochemical interactions as oxygen with hemoglobin. Instead, nitrogen is dissolved in the blood but does not play a role in oxygen transport or exchange.

TRUE

Yes, milk contains nitrogen. The protein in milk, such as casein and whey, are made up of amino acids, which are nitrogen-containing molecules. Nitrogen is an essential component of amino acids, which are the building blocks of proteins found in milk.

Yes, nitrogen mustard vesicants are known to cause blistering. These compounds can damage the skin and mucous membranes, leading to severe blister formation upon contact. They act as alkylating agents, interfering with cellular processes and resulting in tissue injury. The severity of the blistering depends on the concentration and duration of exposure.

Nitrogen fixation. It can only be performed by a very small number of species of anaerobic bacteria.

A method is the following:
NH4Cl + NaNO2 = N2 + NaCl + 2 H2O