2Dimitri Mendeleev Russian scientist 1869 noticed that he arranged elements by their atomic mass Present day periodic table arranged by atomic #
3Period – Horizontal row on the Periodic Table Group/Family – Vertical column on the Periodic Table
4Groups…Here’s Where the Periodic Table Gets Useful!! Elements in the same group have similar chemical and physical properties!!(Mendeleev did that on purpose.)Why?They have the same number of valence electrons.They will form the same kinds of ions.
5Groups are also called families. They are vertical columns.
6Periods Row on the period table Elements in the same period have the same number of electron ringsVery different properties as you move across the tableExamples:Period 1~ H and He 1 electron shellPeriod 2~ Li, Be, B, C, N, O, F, 2 electron shellsEtc……..
8Periodic means having regular patterns or cycles that occur. Chemical symbols- first letter is always capitalized and the second letter is lower case.Elements names are often in different languages. Ex. Sodium (Na) latin word natrium
9Alkali Metals1st column on the periodic table (Group 1) not including hydrogen.Very reactive metalsAlways combined with something else in nature (like in salt).Soft enough to cut with a butter knife1 valence electron
10Alkaline Earth Metals Second column on the periodic table. (Group 2) Reactive metalsAlways combined with nonmetals in nature.Several are important mineral nutrients (Mg and Ca)2 valence electrons
11Transition Metals Elements in groups 3-12 Less reactive harder metals Includes metals used in jewelry and construction.Metals used “as metal.”
12Halogens Elements in group 17 Very reactive, volatile, diatomic, nonmetalsAlways found combined with other element in natureUsed as disinfectants and to strengthen teeth