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Isotopes - is a superscript on the left of the atomic...

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Isotopes, Atomic Numbers and Mass Numbers What characteristic feature of sub-atomic particles distinguishes one element from another? All atoms of an element have the same number of protons in the nucleus Since the net charge on an atom is 0, the atom must have an equal number of electrons . What about the neutrons? Although usually equal to the number of protons, the number of neutrons can vary somewhat. Atoms which differ only in the number of neutrons are called isotopes. Since the neutron is about 1.0087 amu (the proton is 1.0073), different isotopes have different masses. Your friend, Carbon All atoms of the element Carbon (C) have 6 protons and 6 electrons. The number of protons in the carbon atom are denoted by a subscript on the left of the atomic symbol: This is called the atomic number , and since it is always 6 for carbon, it is somewhat redundant and usually omitted. Another number, the "Mass Number"
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Unformatted text preview: is a superscript on the left of the atomic symbol. It denotes the sum of the number of protons and neutrons in the particular isotope being described. For example: refers to an isotope of carbon which has (as expected for the element carbon) six protons, and six neutrons. The following isotope of carbon: has 6 protons (atomic number) and 8 neutrons (8=14-6). This isotope is also known simply as "carbon 14". Carbon 12 is the most common form of carbon (~99% of all carbon). An atom of a specific isotope is called a nuclide . Since all atoms are composed of protons, electrons and neutrons, all chemical and physical differences between elements are due to the differences in the number of these sub-atomic particles. Therefore, an atom is the smallest sample of an element, because dividing an atom further (into sub-atomic particles) destroys the element's unique identitity....
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