For example, oxygen has three stable isotopes, but tin has 10. Simple elements almost always have the same neutron number as their proton number. However, in heavier elements, neutrons outnumber protons. The amount of neutrons is critical for balancing the stability of nuclei. Because oxygen has 8 protons and eight neutrons, it is not surprising that its nuclei are identical to those of tin, which has 14 protons and 14 neutrons.
The reason why oxygen has three stable isotopes and tin only two is due to differences in nuclear binding energy. The most abundant isotope of oxygen is 16O, with a mass number of 16 and 42% abundance. The next most abundant isotope is 17O, with a mass number of 17 and 15% abundance. The third most abundant isotope is 18O, with a mass number of 18 and 7% abundance. Tin has only two stable isotopes, 114Sn and 116Sn. They have equal abundances.
Oxygen has seven radioactive isotopes while tin has nine. Radionuclides are atoms that decay into other elements by loss of electrons or particles. Radioactive elements become more unstable as they age because of emission of high-energy particles that escape detection. Some radioactivities can be used to date materials with relative accuracy up to hundreds of thousands of years. Most natural radioactivity results from the decay of uranium and thorium.
Isotopes are identical atoms with differing numbers of neutrons but the same amount of protons and electrons. The variation in the number of neutrons between an element's isotopes indicates that the isotopes have different masses. Since each particle has a charge equal to its mass, this means that each isotope must have an unequal number of electrons.
Isotopes can be described by their mass number A. For example, carbon has 6 protons and 6 electrons, so its mass is 12.00000000000001 u; nitrogen has 7 protons and 7 electrons, so its mass is 14.00000000000002 u. An atom's mass cannot change, so either there are more particles than atoms or there are fewer. In fact, there are always more particles than atoms because they can combine together to form molecules. Carbon-12 has six neutrons and six protons, while carbon-13 has seven neutrons and seven protons. Because carbon has six electrons, it must have had eight before it formed any atoms, which means that it must have had ten electrons overall. Similarly, oxygen-16 has 8 neutrons and 8 protons, while oxygen-17 has 9 neutrons and 8 protons. There are also less abundant isotopes with lower mass numbers, such as magnesium-28 which has 28 neutrons and 28 protons.
Atoms of an element's multiple isotopes have the same atomic number, but their atomic weight varies. Carbon atoms have six protons. The other isotopes contain 5, 7, or 8 neutrons, but the number of protons is the same. Carbon isotopes are all the same in that each atom has six protons. However, they vary in their neutron count: 12C, 13C, 14C, 15N, 16O, 17O, and 18O.
Isotopes are forms of an element with the same number of protons, but may have different numbers of neutrons. Because of this difference in mass (and therefore size) some elements' isotopes are more stable than others. For example, uranium has 238 protons and 244 neutrons. All its isotopes are heavier than uranium itself. Some of them are very unstable and quickly decay into another form of matter over time scales of millions of years. Others remain as nuclear waste because there is no stable way to dispose of them. But all the uranium's isotopes share the same electron configuration so they can never be separated by chemical means. They can only be differentiated by using special techniques such as mass spectrometry or nuclear physics experiments.
Most elements have several stable and unstable isotopes. An example is oxygen. There are eight oxygen isotopes and all of them are chemically identical; they differ only in their mass. Yet some are stable and some are not.
An element's atomic number is equal to the number of protons in its nucleus. An element's mass number is equal to the sum of its protons and neutrons in its nucleus. Isotopes are atoms of the same element with various mass numbers due to differences in the number of neutrons. Because each neutron adds less mass than a proton, an element's isotopes will have lower mass numbers if they contain more neutrons or higher mass numbers if they contain more protons.
Iodine has two stable isotopes: 123I and 125I. Both forms of iodine have the same number of electrons (Z-shell) in their nuclei but differ in their mass numbers. 123I has 121 electrons and 2 neutrons while 125I has 123 electrons and 2 neutrons. The extra neutron causes 125I to have a higher mass number and therefore be more massive than 123I.
Mass spectrometry can be used to distinguish elements with identical atomic numbers by measuring the mass of their ions. Iodine has an atomic weight of 123.546. Therefore, any molecule containing iodine with an atomic weight greater than 123.546 would be composed of 125I rather than 123I.
Iodine-131 is one of the products of nuclear fission. It has a half-life of 8 days and emits gamma rays that are useful for medical imaging.
The isotope is determined by the quantity of neutrons. " "There are two reasons why isotopes are essential. One is only fundamental science, whereas the other is an attempt to comprehend the atomic nucleus. If you can adjust the amount of neutrons and protons in any way and see what difference it makes, that's a great place to start. Some isotopes are stable, while others are not. The ones that are not stable will decay into stable isotopes over time.
Isotopes are useful because they have different properties. For example, some elements can be found in more than one isotopic state. Carbon has three naturally occurring isotopes: 12C, 13C, and 14C. All living things contain a fixed amount of each type of carbon atom, but they are not identical. The differences between them are small but measurable. Scientists use these differences to identify individuals or groups of individuals who may have similar diets or life styles. They do this by measuring the ratio of 13C to 12C in a sample of someone's hair or bone collagen.
Isotopes also provide information about past events. For example, if you find an unusually high concentration of 15N in soil, that means there was a lot of nitrification happening in the area recently. Nitrogen is used up quickly in plants, so when it becomes concentrated in the soil, that means it came from something that killed other organisms which hold onto nitrogen very tightly.
Finally, isotopes are useful in medicine.
A chemical element's atoms can be of several sorts. These are known as isotopes. They both have the same amount of protons (and electrons), but they have different numbers of neutrons. Because various isotopes contain varying quantities of neutrons, they do not all have the same weight or mass. Some isotopes are stable: they will still be there even if you put them in a container with other elements. Others are radioactive: some components inside their atoms slowly break down, giving off particles and becoming less heavy over time.
Isotopes were first discovered by Anselme Voignard in 1898. He was studying minerals from around the world when he noticed that some contained more than one kind of atom with an excess of neutrons. He called these "extraordinary" atoms "isotopes".
Because each nucleus contains the same number of protons, any difference in mass must come from differences in the numbers of neutrons. Isotopes can be similar elements with different numbers of neutrons - such as oxygen 16O and 18O - or they can be two very different elements with the same number of protons - such as carbon 12C and 13C. The presence of isotopes is what allows scientists to distinguish elements even if they are found together in nature or after an explosion. A sample of rock may contain many elements, but because of the presence of certain isotopes it can be classified as being made up of that element alone.