Isotopes?

[hitmankratos]

Isotopes are the same atoms except that they have additional neurtrons (For example Carbon 13, and 14).

What diffrence can that make?

[Gilded]

Well obviously it affects mass, which is especially apparent in light elements such as hydrogen. But perhaps more importantly it affects nuclear stability. Too many or too few neutrons and things start to fall apart, so to speak, which is why some isotopes are radioactive. The strong force keeps the protons and neutrons together in the nucleus, one of the physics experts can probably explain why certain amounts of neutrons cause instability. AFAIK these stable ratios aren't perfectly understood yet though, for example we can't really determine the half-life of any nucleus by just looking at how many protons and neutrons it has.

[swansont]

Nuclei have energy levels and shells for neutrons and protons, similar to those of electrons, so you can reach a state where a proton or neutron has a higher energy than an empty state of the other particle. The particle will change identity if the nucleus can release energy in doing so, which is what happens in beta decay.

 

Physical, chemical and biological reactions are also affected by isotopes; heavier particle move slower, on average, at a given temperature, and tend to react or diffuse more slowly. For example, there are seasonal variations in the concentration of O-18 and deuterium in water found in ice layers. Heavier isotopes evaporate more slowly and condense more quickly, so the isotopic ratios will differ depending on the conditions.

 

http://www.csa.com/discoveryguides/icecore/review.php

[Pradeepkumar]

there are lots of reactions which depends on the molecular weight

so it makes a difference

 

even if i am wrong dont fail to correct me

[Mr Skeptic]

The chemical differences between isotopes are quite small. However, for isotopes of hydrogen (id, deuterium and tritium) it can be quite significant. Enough so that you can kill yourself by drinking plenty of deuterium water.

[John Cuthber]

It would be easier (and a lot cheaper) to poison yourself with whiskey than with heavy water.

Other than for hydrogen's isotopes the differences in chemistry are generally too small to notice. The only really noticable differences are in the nuclear properties; thing's like neutron capture cross sections.