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Periodic Table Vocabulary. 2012-13. Periodic Trend. a predictable pattern of gradual change of certain properties of elements to increase or decrease as one progresses across a row or down a column. groups/families. vertical columns on the periodic table
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Periodic TableVocabulary • 2012-13
Periodic Trend • a predictable pattern of gradual change of certain properties of elements to increase or decrease as one progresses across a row or down a column
groups/families • vertical columns on the periodic table • have similar properties; “like brothers and sisters” • 18 groups
Periods • Horizontal rows on periodic table • properties change gradually, but predictably as you go across the row • “like cousins” • 7 periods
Atomic number • the number of protons in the nucleus of an atom
Valence Electrons • the electrons on the outermost energy level (shell, orbital) • determines reactivity • the closer to a full shell, the less reactive
Reactivity • the tendency for an element or substance to undergo a chemical reaction, either by itself or with another substance
Metals • elements that: • have luster • are good conductors of heat and electricity • are malleable (can be flattened into sheets) • are ductile (can be stretched into wires) • found on the left side of the “staircase” on the periodic table
Nonmetals • elements that: • are usually gases or brittle solids • are poor conductors of heat and electricity • found on the right side of the “staircase” on the periodic table
Metalloids • elements that: • have different properties of both metals and nonmetals • Often semiconductors • sometimes called “semimetals” • found touching the “staircase” on the periodic table