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The Periodic Table
Periodic table of elements
Term | Definition |
---|---|
Element | Substance that cannot be split up into simpler substances by chemical means |
Triad | Group of three elements with similar chemical properties in which the atomic weight of the middle element is approximately equal to average of the other two |
Newlands' Octaves | Group of elements arranged in order of increasing atomic weight, in which the first and the eighth element of each group have similar properties |
Mendeleev's periodic law | When elements are arranged in order of increasing atomic weight, the properties of the elements vary periodically |
Atomic number | is the number of protons in nucleus of that atom |
Modern Periodic Table | Arrangement of elements in order of increasing atomic number |
Mass Number | Sum of the number of protons and neutrons in the nucleus of an atom of that element |
Isotope | atoms of an element (they have the same atomic number) that have different mass numbers |
Relative atomic mass | Average mass of atoms of element relative to 1/12 th the mass of carbon 12 atom |
Aufbau Principle | states when building up the electronic configuration of an atom in its ground state, the electrons occupy the lowest available level |
Pauli exclusion principle | no more than two electrons may occupy an orbital and they must have opposite spin |