Cosmogenic aluminium-26 was first applied in studies of the Moon and meteorites. Nearly all aluminium on Earth is present as this isotope, which makes it a mononuclidic elementĪluminium-26 is composed of 13 protons, 13 neutrons, and 13 electrons. the only one that has existed on Earth in its current form since the formation of the planet. It is the only primordial aluminium isotope, i.e. Other than 26Al, all radioisotopes have half-lives under 7 minutes, most under a second.Īluminium-27 is composed of 13 protons, 14 neutrons, and 13 electrons. Only 27Al (stable isotope) and 26Al (radioactive isotope, t 1/2 = 7.2×10 5 y) occur naturally, however 27Al comprises nearly all natural aluminium. This is consistent with aluminium having an odd atomic number. Of aluminium isotopes, only 27Al is stable. Mass numbers of typical isotopes of Aluminium are 27. Isotopes are nuclides that have the same atomic number and are therefore the same element, but differ in the number of neutrons. The difference between the neutron number and the atomic number is known as the neutron excess: D = N – Z = A – 2Z.įor stable elements, there is usually a variety of stable isotopes. Neutron number plus atomic number equals atomic mass number: N+Z=A. The total number of neutrons in the nucleus of an atom is called the neutron number of the atom and is given the symbol N. The total electrical charge of the nucleus is therefore +Ze, where e (elementary charge) equals to 1,602 x 10 -19 coulombs. Total number of protons in the nucleus is called the atomic number of the atom and is given the symbol Z. Aluminium is a chemical element with atomic number 13 which means there are 13 protons in its nucleus.
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