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S8 Periodic Table
Science 8 The Periodic Table
Term | Definition |
---|---|
Scientist who discovered the periodic table | Dmitri Mendeleev |
atomic mass | the average number of protons and neutrons in all isotopes of an element |
periodic table | a chart showing all the elements arranged according to the repeating pattern of their properties |
chemical symbol | a one- or two-letter abbreviation for the element |
atomic number | the number of protons in the nucleus of an atom |
the element with 20 electrons | Calcium |
the element with 2 protons and 2 neutrons | Helium |
the element with an atomic mass of 35 | Chlorine |
the element with 5 neutrons | Berilium |
period | a row in the periodic table |
the number of periods in the periodic table | seven |
lanthanides | rare earth metals, #57-71 |
actinides | radioactive elements, #89-103 |
transuranium elements | the elements that come after uranium in the periodic table, most of which do not occur in nature |
group | a column in the periodic table, a family of elements |
the number of groups in the periodic table | eighteen |
alkali metals | group 1, very reactive metals (not found as free elements in nature - only in compounds), can be soft and shiny |
alkaline earth metals | group 2, harder and denser metals, quite reactive, not found in nature - only combined with other things |
transition metals | the metals in groups 3-12, most are hard and shiny solids with high melting points; some are found in nature |
boron family | group 13, metalloids, boron and then post-transition metals |
carbon family | group 14, carbon is a nonmetal, rest are metalloids |
nitrogen family | group 15, two nonmetals: nitrogen and phosphorus |
oxygen family | group 16, three nonmetals: oxygen (gas), sulfur, and selenium, two metalloids: tellurium and polonium |
hydrogen | not in a group, the element with the simplest atoms |
halogen family | group 17, nonmetals: fluorine, chlorine, bromine, and iodine; salt-forming |
noble gases | group 18, not very reactive |