Isotopes ?

There are isotopes in the periodic table. Subtracting atomic number from atomic mass give the average number of neutrons in a sample of element.

In the case where the atomic mass is a hole number (to 1 or 2 decimal places) e.g. carbon it is likely that the vast majority of the element is composed of only one isotope. Greater than 99% of naturally occuring carbon is carbon-12.

Chlorine has two naturally occuring isotopes, Cl-35 and Cl-37. Because of the different abundances of these two naturally occuring isotopes the average atomic mass is 35.5 (as found on the periodic table).

So, all elements are isotopes, though some elements only have one naturally occuring isotopes.

Also, isotopes do not necesarily have to be radioactive. Though often an element with excess neutrons can be unstable, such that radioactive decay occurs.

All the mass numbers in the periodic table are realative atomic masses, that effectively means the arithimetic mean, or average mass of all the atoms of each type in the world.

So all atoms are therefore isotopes. The definition of an isotope is atoms with the same proton number but different numbers of neutrons.

As a general rule if the neutron number differs significantly from the proton number the atom will be unstable and decay with the release of radiation.

There are many exceptions, for example lithium in group one has a relative mass of seven and atomic number 3 so it has 4 neutrons and is very stable.

Atoms with atomic number over 83 Bismuth are all unstable as there neutron numbers are significantly higher than the proton number.

Hope this helps.

The number of neutrons in an atomic nucleus is found from the mass number (NOT the atomic mass) minus the atomic number. Potassium contains some atoms with a mass number of 39 (19 protons and 20 neutrons), some of 40 (20 protons, 20 neutrons) and some of 41 (21 protons, 19 neutrons). These different types of potassium atoms are known as isotopes, but they are all potassium because they all have 19 protons. The atomic mass (or more correctly, the Relative Atomic Mass) is simply the average of the different mass numbers weighted according to their abundance. In the case of potassium, there is 93.1% K-39, 0.01% K-40 and 6.89% K-41, leading to a RAM of 39.14

Not all isotopes are radioactive (you have been watching too much of the Simpsons). K-39 and K-41 are stable but K-40 is radioactive. It is not simple to predict the stability of a nucleus as the forces between protons and neutrons are not like the ones we are used to experiencing (like gravity and electrostatic forces).

Firstly, the atomic mass of potassium is 39. The atomic mass is not the same as the atomic number. The atomic mass is the weighted average isotopic mass of the naturally occurring isotopes of an element. The number of neutrons an element contains is equal to its atomic mass minus its atomic number. Elemental potassium (the one found on the periodic table) contains 18 neutrons and 18 protons. An isotope of potassium has the same number of protons, yet different numbers of neutrons. An isotope of potassium, K-55, still has 18 protons, but now has 37 neutrons. I hope this explains your question.

Source(s): My vast and allknowing mind.

Isotopes) 20 neutrons is correct. Isotopes has always struck me as a strange term’the word means”same weight”;the only way I can make sense of it is that the isotopic mass of one element can have the same mass as an isotope of one or more other chemical elements.

The also bit.Quite deep this .bear in mind how small, to us. a nucleus is,then keep in mind that protons are particles which all have a + charge and so repel each other very strongly, so the neutons are the nuclear nuts and bolts that bind them together.It seems you need approximately as many neutrons as protons otherwise too many or too few will cause the nucleus to fly apart like an over rev’d unbalanced car engine.When this happens a ot of energy is released and even a netron or proton can be altered so that other particles are given out.

A) the periodic table contains only the mean value of the isotopes rounded to the nearest 0.5 (guess). Generally since C12 is ~99% and C13 ~ 0.999% and C14 ~ 0.1% and so the mean is practically 12.

B) Isotopes are radioactive because the strong nuclear force affects hadrons (neutrons and protons). The extra mass increases this force by the electrostatic force will decrease assuming the protons are pushed further apart. They can collapse under their own gravity too and give off radiation

Isotopes are atoms with the same atomic number but different mass number due to the difference in number of neutron in the nucleus of the atom .

Secondly there are isotopes in the periodic table examples are are hydrogen isotope and calcium isotope

Hi,

Isotopes are atoms with the same number of protons but different number of neutrons. Remember, for an atom to be stable (not to decay), protons and neutrons must be equal in number. Atomic mass minus atomic number does not determine isotopes. It only tells us the number of protons and with that number of protons, it could have different number of neitrons in it.

If number of protons and number of neutrons is not equal, atom is unstable and it decays. If it decays, it releases particles called ions which is radioactive and charged. Ions are negatively charged particles. If on the decay process,it continued releasing ions,negative electrons will be higher in number than protons. This results to an atom that is not neutral. An atom that is not neutral is always radioactive.

Isotopes are radioactive because the lack of neutrons makes the nucleus unstable as the repelant forces between the protons are more concentrated

isotopes are atoms of the SAME element with different no. of neutrons