chemistry

Isotopes of nitrogen

Isotopes of nitrogen is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Isotopes of nitrogen rather than just read about it. In short: Natural nitrogen (7N) consists of two stable isotopes: the vast majority (99.62%) of naturally occurring nitrogen is nitrogen-14, with the remainder (0.38%) being nitrogen-15. Thirteen radioisotopes are also known, with atomic masses ranging from 9 to 23, along with three nuclear isomers.

Key takeaways

Isotopes of nitrogen belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Isotopes of nitrogen to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Isotopes of nitrogen from memory before moving on to harder problems.

Reference excerpt

Natural nitrogen (7N) consists of two stable isotopes: the vast majority (99.62%) of naturally occurring nitrogen is nitrogen-14, with the remainder (0.38%) being nitrogen-15. Thirteen radioisotopes are also known, with atomic masses ranging from 9 to 23, along with three nuclear isomers. All of these radioisotopes are short-lived, the longest-lived being 13N with a half-life of 9.965 minutes. All of the others have half-lives shorter than ten seconds. Isotopes lighter than the stable ones generally decay to isotopes of carbon, and those heavier beta decay to isotopes of oxygen. Nitrogen-13 is a positron emitter and one of the main isotopes used in medical PET scans.

List of isotopes

Nitrogen-13 Nitrogen-13 (13N) has a half-life of a little under ten minutes. It is produced in the atmosphere when gamma rays (for example from lightning) knock neutrons out of nitrogen-14. 13N decays to 13C, emitting a positron. The positron quickly annihilates with an electron, producing two gamma rays of about 511 keV. After a lightning bolt, this gamma radiation dies down with a half-life of 10 minutes, but these low-energy gamma rays go on average only about 90 metres through the air, so they may only be detected for a minute or so as the "cloud" of 13N and 15O floats by, carried by the wind. Nitrogen-13 plays a significant role in the CNO cycle, which is the dominant source of energy in main sequence stars more massive than 1.5 times the mass of the Sun. Nitrogen-13 is used in positron emission tomography in the form of 13N-labelled ammonia, for example for myocardial perfusion imaging. It can be produced with a medical cyclotron, using a target of pure water with a trace amount of ethanol. The reactants are oxygen-16 (present as H2O) and a proton, and the products are nitrogen-13 and an alpha particle (helium-4):

1H + 16O → 13N + 4He In this endothermic reaction, the proton must be accelerated to have a total energy greater than 5.66 MeV. The presence of ethanol allows the formation of ammonia as nitrogen-13 is produced. Other routes of producing 13N-labelled ammonia exist, some of which facilitate co-generation of other light radionuclides for diagnostic imaging.

Nitrogen-14 Nitrogen-14 makes up the clear majority of natural nitrogen, about 99.62%, and is responsible for the Earth's stable atmosphere. Nitrogen-14 is one of the very few stable nuclides with both an odd number of protons and of neutrons (seven each) and is the only one to make up a majority of its element. Unpaired protons or neutrons contribute a half-integer nuclear spin, which in this case is a spin 1/2 orbital, giving the nucleus a total magnetic spin of one (as the spins prefer to align). The original source of nitrogen-14 and nitrogen-15 in the Universe is believed to be stellar nucleosynthesis, where they are produced as part of the CNO cycle. Nitrogen-14 is the source of naturally occurring, radioactive, carbon-14. Some kinds of cosmic radiation cause a nuclear reaction with nitrogen-14 in the upper atmosphere of the Earth, creating carbon-14, which decays back to nitrogen-14 with a half-life of 5700 years.

Nitrogen-15 Nitrogen-15 is a rare stable isotope of nitrogen, comprising about 0.38%. Nitrogen-15 presents one of the lowest thermal neutron capture cross sections of all isotopes. Nitrogen-15 is frequently used in NMR (Nitrogen-15 NMR spectroscopy). Unlike the more abundant nitrogen-14, which has an integer nuclear spin and thus a quadrupole moment, 15N has a fractional nuclear spin of one-half, which offers advantages for NMR such as narrower line width. As most nitrogen NMR studies look at a single nitrogen atom in an organic molecule, isotopic labeling is feasible. Nitrogen-15 tracing is a technique used to study the nitrogen cycle.

Nitrogen-16 The radioisotope 16N is the dominant radioactivity source in the coolant water of nuclear reactors cooled by water during normal operation. It is produced from 16O (in water) via an (n,p) reaction, in which the 16O atom captures a neutron and expels a proton. It has a short half-life of 7.13 seconds, but its decay back to 16O produces high-energy gamma radiation (6.13 MeV principal line). Because of this, access to the primary coolant piping in a pressurised water reactor must be restricted during reactor power operation. It is a sensitive and immediate indicator of leaks from the primary coolant system to the secondary steam cycle and is the primary means of detection for such leaks.

Isotopic signatures

See also Isotopes of oxygen Isotopes of carbon Isotopes of beryllium Isotopes of helium

References

Worked examples

Example 1 — a first encounter with Isotopes of nitrogen

Start with the simplest possible case. Write down what Isotopes of nitrogen claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Isotopes of nitrogen before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Isotopes of nitrogen ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Isotopes of nitrogen

In research: Isotopes of nitrogen appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Isotopes of nitrogen in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Isotopes of nitrogen is common in secondary-school and first-year university syllabi. It links to neighbouring topics Isotopes of nitrogen, Lists of isotopes by element, Nitrogen, so understanding it makes those chapters shorter.
In everyday life: Look for Isotopes of nitrogen outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Isotopes of nitrogen in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Isotopes of nitrogen means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Isotopes of nitrogen out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Isotopes of nitrogen in simple terms?

Why does Isotopes of nitrogen matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Isotopes of nitrogen?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Isotopes of nitrogen.