The Periodic Table Horizontal Rows are called Periods. Elements in the same period have the same number of energy levels for ground state electron configurations. Vertical Rows are called Families or Groups. Families have the same valance electron configurations. Family 1 Alkali Metals Family 1 Most active of all the metals One valance electron in outer most energy level. (ns1: Li – 1s22s1, Na – 1s22s22p63s1) Lose the one valance electron when forming chemical bonds. Form +1 ions. All atoms “want to have an octet of valance electron so they will gain lose or share electrons to get to this “magic number.” Family 2 Alkaline Earth Metals Family 2. Second most active of the metals. Two valance electrons (ns2: Be – 1s22s2, Mg – 1s22s22p63s2) Lose both valance electrons when forming chemical bonds. Form +2 ions. Family 17 Halogens Family 17. Most active of the nonmetals. 7 valance electrons (ns2np5: F – 1s22s22p5, Cl – 1s22s22p63s23p5) Gain 1 electron to obtain octet. Form -1 ions. Halogens is Greek for salt former; they form salts when reacting with metals. Family 18 Noble Gases – Inert Gases Family 18. Most inactive of all elements. Do not normally form compounds. 8 valance electrons (ns2np6: Ne – 1s22s22p6, Ar – 1s22s22p63s23p6) A perfect octet of electrons so they do not gain or lose electrons to form compounds. Helium is only 1s2, but it still does not form compounds because the 1st energy level is filled with only 2 electrons. Group B Elements Transition Metals Family 3 – Family 12 Less active than alkali or alkaline earth metals. One or two valance electrons. All transition metals have ns1 or ns2 valance electron structures. They have (n-1)d1 – (n-1)d10. They have oxidations (ion charges) of +1 through +7. Transition metals do not obtain octets because they have “d” electrons involved in bonding. Inner-transition Metals Stair Step Line: Divides Metals and Nonmetals Metalloids Metalloids Have properties of both metals and nonmetals. Semiconductors; metals are conductors and nonmetals are nonconductors. If element is on the metal side treat as a metal; if it is on the nonmetal side treat as a nonmetal. Boron Family Family 13 Boron – metalloid Aluminum and rest are metals. 3 valance electrons. ns2np1 +3 ion charge Carbon Family Family 14 Carbon – nonmetal Silicon and germanium are metalloids. Tin and lead are metals. 4 valance electrons. ns2np2 Carbon and silicon can be +4 or -4 or it can share electrons to form bonds. Tin and lead can be +2 or +4. Nitrogen Family Family 15 Nitrogen and phosphorus are nonmetals. Arsenic and antimony are metalloids. Bismuth is a metal. 5 valance electrons. ns2np3 Nitrogen and phosphorus are usually +3. Bismuth and antimony are +3 or +5. Oxygen Family Family 16 Oxygen, sulfur and selenium are nonmetals. Tellurium and polonium are metalloids. 6 valance electrons. ns2np4 Oxygen and sulfur are usually -2. S, P, D, F Block Elements Noble Gas Configurations History and Periodic Properties of the Periodic Table Objective: explain the use of chemical and physical properties in the historical development of the Periodic Table. Objective: use the Periodic Table to identify and explain periodic trends, including atomic and ionic radii, electronegativity, and ionization energy. The Father of the Periodic Table Dmitri Mendeleev’s Periodic Table History of the Periodic Table John Newlands: 1864 He proposed an organization scheme for the elements. Newlands noticed that when the elements were arranged in order of increasing atomic mass, their properties repeated every eight elements. This pattern is “periodic” because it repeats at regular intervals. History: Part II Dmitri Mendeleev: 1869 He noticed the same “periodic” pattern as Newlands. By arranging the elements in order of increasing atomic mass into columns with similar properties Mendeleev credited the first periodic table. He predicted the properties of scandium, gallium, and germanium. History: Part III Mendeleev’s table had problems. When new elements were discovered it was found that the order was not correct. Henry Moseley: 1913 Mosley discovered that each element had a unique number of protons. He proposed that the periodic table be arranged in order on increasing atomic number. The Periodic Law There is a periodic repetition of chemical and physical properties of the elements when they are arranged in order of increasing atomic number. The properties of the elements are related to their atomic numbers and their location on the periodic table. This repetition can be seen in both families and periods. Atomic Radius Atomic Radius Atomic radius is the “size” of an atom. Atomic radius is half the distance between the nuclei of two atoms. Atoms with a large atomic radius will be easy to remove an electron from; these are usually the metals. Atoms with a small radius are harder to remove an electron from; these are usually the nonmetals. Largest radius = francium Smallest radius = helium Ionization Energy Ionization energy is the energy required to remove one electron from an atom. Elements with low ionization energies tend to lose electrons and form positive ions. Metals have low ionization energies, nonmetals are high. Electronegativity Indicates the relative ability of an atom to attract electrons in a chemical bond. .