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8Sci CH5
8th Science CH5 The Periodic Table
Term | Definition |
---|---|
alkali metals | column 1 elements in the periodic table of elements; alkali metals are so reactive that they are never found uncombined in nature |
alkaline earth metals | in the periodic table of elements, alkaline earth metals are column 2 elements such as magnesium, strontium, and barium, and are not as reactive as alkali metals |
atomic mass | average mass of the isotope of an element found in nature; calculated by determining the average mass of a sample of the element’s atoms |
atomic number | the number of protons in an atom of the element; atoms of the same element always have the same number of protons; elements appear in the periodic table of elements in order of increasing atomic number |
family of elements | organizational group in the periodic table of elements in which the elements are listed in vertical columns based on their similar physical and chemical properties |
isotopes | atoms of the same element with different numbers of neutrons; radioactive isotopes can be used to precisely determine levels of drugs, hormones, or viruses in a patient’s body. |
mass number | the total number of protons and neutrons in the nucleus of an atom |
period | one of the 7 horizontal rows in the periodic table of elements; each period starts as the pattern of chemical and physical properties of the elements begins to repeat itself; a period is made up of a series of elements with increasing atomic number |
periodic table | organizes all known elements into a table based on atomic mass & structure, and helps you predict how elements will react with one another; elements are organized into columns and rows and shows an element’s atomic number, symbol, name, and atomic mass |