Calcium 20 Ca has 26 known isotopes, ranging from 35 Ca to 60 Ca. There are five stable isotopes 40 Ca, 42 Ca, 43 Ca, 44 Ca and 46 Ca , plus one isotope 48 Ca with such a long half-life that for all practical purposes it can be considered stable. The most abundant isotope, 40 Ca, as well as the rare 46 Ca, are theoretically unstable on energetic grounds, but their decay has not been observed. Calcium also has a cosmogenic isotope , radioactive 41 Ca, which has a half-life of 99, years. Unlike cosmogenic isotopes that are produced in the atmosphere , 41 Ca is produced by neutron activation of 40 Ca.
In chemistry naming and notation are essential for clear communication. There are three common ways we can represent an element. For the Periodic Table, the Atomic Number is on top and the average atomic mass is on the bottom. For nuclear notation, the mass number of the isotope goes on top and the atomic number goes on the bottom.
Although all atoms of an element have the same number of protons, individual atoms may have different numbers of neutrons. These differing atoms are called isotopes. All atoms of chlorine Cl have 17 protons, but there are chlorine isotopes with 15 to 23 neutrons. Only two chlorine isotopes exist in significant amounts in nature: those with 18 neutrons
This worked problem demonstrates how to determine the number of protons and neutrons are in the nucleus of an isotope. One of the harmful species from nuclear fallout is the radioactive isotope of strontium, 90 38 Sr assume the super and subscripts line up. How many protons and neutrons are there in the nucleus of strontium?