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Periodic Trends
Key Terms
Word | Definition |
---|---|
periodic law | the law that states that the repeating chemical and physical properties of elements change periodically with the atomic numbers of the elements |
periodic table | an arrangement of the elements in order of their atomic numbers such that elements with similar properties fall in the same column, or group |
lanthanide | a member of the rare-earth series of elements, whose atomic numbers range from 58 (cerium) to 71 (lutetium) |
actinide | any of the elements of the actinide series, which have atomic numbers from 89 (actinium, Ac) through 103 (lawrencium, Lr) |
alkali metal | one of the elements of Group 1 of the periodic table (lithium, sodium, potassium, rubidium, cesium, and francium) |
alkaline-earth metal | one of the elements of Group 2 of the periodic table (beryllium, magnesium, calcium, strontium, barium, and radium) |
transition element | one of the metals that can use the inner shell before using the outer shell to bond |
main-group element | an element in the s-block or p-block of the periodic table |
halogen | one of the elements of Group 17 of the periodic table (fluorine, chlorine, bromine, iodine, and astatine); halogens combine with most metals to form salts |
Atomic radius | one-half of the distance between the center of identical atoms that are not bonded together |
Ion | an atom, radical, or molecule that has gained or lost one or more electrons and has a negative or positive charge |
Ionization | the process of adding or removing electrons from an atom or molecule, which gives the atom or molecule a net charge |
Ionization energy | the energy required to remove an electron from an atom or ion (abbreviation, IE) |
Electron affinity | the energy needed to remove an electron from a negative ion to form a neutral atom or molecule |
Cation | an ion that has a positive charge |
Anion | an ion that has a negative charge |
Valence electron | an electron that is found in the outermost shell of an atom and that determines the atom's chemical properties |
Electronegativity | a measure of the ability of an atom in a chemical compound to attract electrons |