Isotopes

The process is called decay, or sometimes nuclear decay. A link can be found below.

Half the original amount.

Go to the periodic table and look up the atomic number of iron (Fe). The atomic number of iron is equal to the number of protons in iron. Mass number is the number of protons plus the number of neutrons so add up the two values.

Rubidium has two natural isotopes (85Rb and 87Rb) and 30 artificial isotopes.

No, it is a compound. If you read the definitions of isotope and compounds, the difference should become quite clear.

No, it is a compound. If you read the definitions of isotope and compounds, the difference should become quite clear.

No, it is a compound. If you read the definitions of isotope and compounds, the difference should become quite clear.

No, it is a compound. If you read the definitions of isotope and compounds, the difference should become quite clear.

Carbon-14.

Interestingly, there are natural ways that differences in the abundance of isotopes can arise.

The obvious example is carbon, where the different abundances of carbon 14 are used to date archeological artifacts.

For most elements, the isotopes were determined billions of years ago when the Earth condensed out of the swirl of matter around the newly formed Sun, so the mix of isotopes then was what it is now and things were pretty well mixed then. Even if not, the process by which the isotopes were made is pretty much the same all over the universe so different stuff combined from different parts of the universe should still have about the same isotopic mix. (See related link to Nucleosynthesis.)

There are a couple of things that can cause the isotopic ratios to change. In the case of carbon, the cause is bombardment of the atmosphere by cosmic rays with enough energy to cause nuclear reactions. Carbon 14 and Iodine 129 are produced by this process and they are termed "cosmogenic nuclei." So, objects with old carbon, not having exchanged carbon with the atmosphere will have less carbon 14 because whatever was there decayed and was not replenished.

There is also the process of natural radioactive decay of things like uranium-235, uranium-238, and thorium-232 produce various elements. These elements will not necessarily have the same isotopic composition as the element that was naturally occurring at the time the Earth was created.

Of course, one might ask if materials that come to Earth from outer space, e.g. meteorites, count as "naturally occurring." One would not expect them to have the same isotopic composition exactly as what is on Earth originally.

There are other differences, such as the rate of diffusion that are different for different isotopes. A molecule of water with a deuterium diffuses at a different rate than one just a tiny bit lighter. Such processes may lead to depletion of lighter isotopes in samples.

Those are a few obvious mechanisms that may create different abundances of isotopes in different samples of the same element, but there are surely more. This answer has not given any indication of which might be the most common mechanisms, except for carbon 14.

isotopes of a given element differ in the number of neutrons they have.

Oxygen-18 has 8 electrons and protons; the number of neutrons is 10.

Hydrogen-1 isotopes have one proton and no neutrons. Hydrogen-2 isotopes have one proton and one neutron.

A molecule is a bond of two or more atoms, resulting in a chemically inert compound. The atoms share electrons, filling all outer shells of the incorporated atoms. An atom requires so many electrons per shell, in order to be electrically neutral; the first level, that being the closest to the nucleus, requiring two electrons to be balanced, the second shell filling 6 electrons, 10 in the third shell and increasing exponentially the further away from the nucleus. Each shell can only fit that many electrons, but a shell with fewer electrons in a shell than it takes to fill it (with the exception of an entirely empty shell) makes the atom more prone to bonding with another atom. This is the case with Hydrogen, with only 1 electron in the first shell, but requiring 2 to fill it's first shell; naturally bonds with another hydrogen atom forming H2, a diatomic molecule; or a molecule made up of only two atoms. Conversely, Helium, the second atom on the periodic table, consisting of two electrons in it's first shell, is naturally neutral and is part of the Nobel gases on the periodic table; elements that have a natural fill of their electron shells with just one atom. These elements have a low chemical reactivity and seldom bond with other material. An isotope is an atom of a particular element, wit a different atomic mass than the normal element. It possesses the same number of electrons and protons, but posses a varying number of neutrons in it's nucleus. H1, the most common isotope of Hydrogen, consists of a hydrogen atom that contains one proton and no neutron in the nucleus. Physical properties of isotopes can vary, some even being radioactive while others are inert.

The atomic masses shown on the Periodic Table and listed in chemistry textbooks are "weighted" averages of all the naturally occurring isotopes for the particular element in question. The higher the abundance of a particular isotope, the more that isotope contributes to the overall weighted average - that is, to the Atomic Mass on the Periodic Table. Since hydrogen's atomic mass is 1.00 794 atomic mass units, it is clear that the Hydrogen-1 isotope is the most abundant of the three naturally occurring isotopes of hydrogen: protium, deuterium, and tritium. Protium makes up far more than 99% of any naturally occurring sample of hydrogen with deuterium (1 proton and 1 neutron) making up almost all of the rest. Tritium (1 proton and 2 neutrons) is typically present only in trace amounts.

To determine the average atomic mass, the masses of the individual isotopes and their relative abundances are measured using a mass spectrometer. Then the fractional abundance is multiplied by the measured isotopic mass for each isotope and the products of these multiplications are then added together to give the recorded atomic mass on the Periodic Table.

No. isotopes are radioactive because the ratio of protons to neutrons is not right. As proton # increases, more and more neutrons are needed to maintain nuclear stability. If an atom has too many, or too few neutrons, it will be radioactive. Excess (or deficient) electrons are call ions.

Nucleons are the particles that make up the nucleus of an atom. That means protons and neutrons. The number of nucleons here would be 12 because the 6 protons and 6 neutrons add up to 12 nucleons.

The relationship between atomic mass and relative abundance of isotopes was the mas number is the number of protons and neutrons in a normal atom of the element and tha atomic mass is the actual mass of the atom, measured in grams.

For two isotopes to be of the same element it has to have the same atomic number and a different mass number. This means 3116X and 3216X are the same element.

There is only one abundant isotope of fluorine and that is 19F
Fluorine-19 is the most common isotope, its abundance is classed as 100% because no other Fluorine isotopes exist in significant quantities. It is also the only stable Fluorine isotope.

c.
half-life

Because the structure of their nuclei is unstable: too many or too few neutrons, excess energy causing metastable state, etc. To get more stable they decay, emitting alpha, beta, and/or gamma radiation.

Isotopes of a chemical element have the same number of protons and electrons but a different number of neutrons.
A radioactive isotope is unstable and can emit nuclear radiations.

Yes.......most likely. I can't think of anything to do with Uranium, that isn't radioactive!

--------

Uranium natural isotopes are not so radioactive compared with other isotopes; but all the isotopes of uranium are radioactive.

This is the deuterium isotope, which has a nucleus of one proton and one neutron, whereas the predominant hydrogen isotope has just a proton. In natural water on earth, which is a compound of hydrogen and oxygen, H2O, there is a small proportion of water made from deuterium instead of normal hydrogen, this is often written as D2O. To make heavy water this compound is extracted, so you don't make the heavy water, you separate it out from natural water.

The half life of actinium (for the natural isotope 227Ac) is 21,773 years.