Biology-(atoms, electrons, isotope...etc) ????

Question

It says the atom's reactivity level depends on the amount of electrons since one type of element always has that same proton number anyways..

however, isotopes is an element w/ same number of protons but differnt number of neutrons...does that determine the reactivity too?

....can someone just clear that up for me?
thank you

Answer 1

No, it should not. Valence electrons are what determines the reactivity, from the inert Noble Gases (8 valence electrons) to the highly reactive Alkaline Metals (1 valence electron), as an atom is stable when the outer level is filled (there are exceptions).

Answer 2

Different isotopes have the same reactivity, since they differ only by the number of neutrons, which have a neutral change and therefore don't result in any extra electrons. Take Hydrogen, for example. It's got one proton, and one electron (the - of the electron balances out the + of the proton). That unpaired electron makes it very reactive (which is why we usually see H2, or H as part of another molecule, rather than just floating around).

Deuterium, an isotope of Hydrogen, contains one proton, one neutron, and one electron (still one + in the nucleus, and one - for the electron). Since it has that unpaired electron, its reactivity is the same. The same is true of Tritium, with one proton, two neutrons, and one electron.

There are a few differences, however. First, the more neutrons you add, the more unstable the atom becomes, so many isotopes tend to be radioactive.

Second, different isotopes may behave a little differently in biological systems. If you were to replace all of the hydrogen in your diet (in sugars, proteins, water, etc) with deuterium, you'd be in trouble. Cells are very small, but compared to an atom, they are huge. A lot of cell processes are dependent on proximity, and though Hydrogen and Deuterium have the same reactivity, Deuterium has twice as much mass. Deuterium would still undergo the same reactions in a cell as Hydrogen, but it would do it ever so slightly slower. The molecules that the Deuterium was incorporated into would also be heavier, and move a little slower. Though very slight, this change in kinetics could cause a lot of trouble on the scale of an organism. You would have to ingest a LOT of Deuterium, and Deuterium-containing molecules for this to be a problem, since it occurs naturally and doesn't cause us any problems at these very small amounts.

Answer 3

An atom's reactivity level actually depends on the number of UNPAIRED electrons on the outermost shell of the atom...of course there are other factors like the size of the atom...

Isotopes don't determine reactivity...but there are isotopes that are radioactive while others are not...but that has nothing to do with reactivity...also extra neutrons do not contribute to the charge of the atom...so no effect to reactivity...