 | Term | Definition |
| |
elemental symbol |
symbol assigned to an element based on the name of the element, consisting of one capital letter or a capital letter followed by a lower case letter |
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compound formula |
symbol for the molecule of a compound, consisting of the symbols of the atoms found in the molecule. atoms present in numbers greater than 1 have the number indicated by subscript |
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nucleus |
central core of atoms that contains protons, neutrons and m ost of the mass of atoms |
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atomic number of an atom |
number equal to the number of protons in the nucleus of an atom (symbolically represented by Z) |
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mass number of an atom |
number equal to the sum of the number of protons and neutrons in the nucleus of an atom (symbolically represented by A) |
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isotopes |
atoms that have the same atomic number but different mass numbers (of the same element that have a different number of neutrons) |
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atomic mass unit (u) |
unit used to express the relative masses of atoms. one u is equal to 1/12 the mass of an atom of carbon -12 |
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atomic weight |
mass of an average atom of an element expressed in atomic mass units |
| |
molecular weight |
relative mass of a molecule expressed in atomic mass units and calculated by adding together the atomic weights of the atoms in the molecule |
| |
mole |
number of particles (atoms or molecules) contained in a sample of element or compound with a mass in grams equal to the atomic or molecular weight. 1 mol = 6.022 x 10^23 particles |
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