Periodic Table Key Concepts
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Periodic Table Key Concepts Periodic Table Basics The periodic table is a table of all the elements which make up matter Elements initially grouped in a table by Dmitri Mendeleev Symbols – each element has a symbol which is either a Capital Letter or a Capital Letter followed by a lower case letter Atomic Number – the number above an element’s symbol which shows the number of protons Atomic Mass – the number found below an elements symbol which shows the mass of the element. Mass = the number of protons + the number of neutrons Metals – the elements which have the properties of malleability, luster, and conductivity o These elements are good conductors of electricity & heat. o Found to the left of the zig-zag line on the periodic table Nonmetals – do not have the properties of metals. Found to the right of the zig-zag line Metalloids – elements found along the zig-zag line of the periodic table and have some properties of metals and nonmetals (B, Si, Ge, As, Sb, Te, and Po) Groups The columns going up and down (There are 18 groups) Group 1: Hydrogen, Lithium, Sodium, Potassium, Rubidium, Cesium, and Francium Elements arranged so that elements with similar properties would be in the same group. o Group 1 Alkali Metals - highly reactive metals o Group 2 Alkali Earth Metals – reactive metals o Group 3-12 Transition Metals o Group 17 Halogens – highly reactive non-metals o Group 18 Noble Gases - do not react or combine with any other elements. Elements are grouped according to their properties or reactivity Reactivity is determined by the number of electrons in an element’s outer energy level These electrons are called valence electrons Periods The rows that run from left to right on the periodic table (There are 7 periods) Period 1 contains 2 elements, Hydrogen and Helium. Period 2 contains 8 elements: Lithium, Beryllium, Boron, Carbon, Nitrogen, Oxygen, Fluorine, Neon The different periods represent different electron energy levels. o Elements in period 1 have electrons in just one energy level. o Elements in period 2 have electrons within two different energy levels. Periodic Trends Metallic properties – the properties that define a metal tend to increase going to the left and down on the periodic table (malleability, luster, and conductivity) Atomic mass – increases going to the right and down on the periodic table Atomic radius – increases going down on the periodic table Periodic Table Key Concepts .