Periodic Table

• periodic table - a table that shows the chemical properties of the elements in order of increasing atomic number
• elements - pure substances that cannot be broken down into simpler substances by chemical means
• periods - term called for the 7 horizontal rows from the periodic table; states how many energy levels an element has
• groups - term used to describe the 18 vertical columns on the periodic table; states how many valence electrons an element has
• alkali metals - naturally exist as compounds with other elements since they are very reactive, low densities, and low melting point; group 1
• alkaline earth metals - exists as solid; highly reactive, heat, electricity; group 2
• transition metals - hard, shiny, and lustrous solids, high thermal and electrical conductivity; high melting points , often take on multiple charged states; group 3-12
• boron family - usually hard, brittle, and have a low melting point; good conductors of heat and electricity; group 13
• carbon family - also called as tetrels; have a much higher melting and boiling point than group 13; group 14
• nitrogen family - also called as pnictogens; may be transparent, either diamagnetic or paramagnetic at room temperature and may conduct electricity when heated; group 15
• oxygen family - also called chalcogens; contains non-metals and metalloids; many of these elements at high concentrations are toxic; group 16
• halogens - nonmetallic elements that are highly reactive in nature; react violently, particularly with metals, poor conductors of heat and electricity, low boiling and melting points (insulators); group 17
• noble gases - colorless, odorless, and nonflammable under standard conditions; most stable elements and least reactive nonmetallic gases; group 18
• atomic number - number of protons in the nucleus of an atom, equal to the number of electrons in the outermost shell
• atomic symbol - the symbol used to represent an element in the periodic table and also used as a shorthand and in chemical equations
• mass number - the total number of protons and neutrons in the nucleus of an atom
• metals - conduct electricity and heat well, malleable and ductile
• non-metals - do not conduct electricity or heat well, brittle
• metalloid - element that has physical and chemical properties of both metal and non-metal