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The Periodic Table: Families & Periodic Trends The Physical Science Series 2005©Doug Gilliland Honors Physical Science Sarasota High School 1 Mendeleev’s Table (1871) While it was the first periodic table, Mendeleev had very different elements, such as the very reactive potassium and the very stable copper, in the same family. Forty years later Moseley rearranged the elements by their atomic number which gave the table better periodicity. Mendeleev 2 Short form of the Table Moseley In 1915 Moseley rearranged the elements by their atomic number. Long form of the Table 3 Chinese Periodic Table Notice that the chemical symbols are in English. This is true throughout the world. 4 IA 1 2 3 4 5 6 7 IIA 6 7 Periods run horizontally. All elements of a period have the same number of electron energy levels. All the elements from rubidium to xenon have 5 electron energy levels. Periods & Families VIIIA IIIA IVA VA VIA VIIA Families, aka Groups, run vertically. All elements of a familyhave the same number ofvalence electrons whichdetermine an element’s chemical & physical properties 5 Alkali Metals, Group 1-A Lithium, Sodium, Potassium, Rubidium, Cesium & Francium IA VIIIA IIA IIIA IVA VA VIA VIIA 6 Alkaline Earth Metals, Group 2-A Less reactive than the alkali metals but more reactive than the other metals. IA VIIIA IIA IIIA IVA VA VIA VIIA 7 Transition Metals Generally stable metals such as iron, gold, silver, copper, zinc, & nickel. IA VIIIA IIA IIIA IVA VA VIA VIIA 8 IA Boron Family, 3-A Boron, Aluminum, Gallium, Indium and Thallium. VIIIA IIA IIIA IVA VA VIA VIIA 9 Carbon Family, 4-A Contain a wide variety of elements from 1 nonmetal (C), 2 metalloids (Si & Ga) and 2 metals (Pb & Sn). IA VIIIA IIA IIIA IVA VA VIA VIIA 10 Nitrogen Family, 5-A Nitrogen, Phosphorus, Astatine, Antimony & Bismuth. IA VIIIA IIA IIIA IVA VA VIA VIIA 11 IA Oxygen Family, 6-A Oxygen, Sulfur, Selenium, Tellurium & Polonium. IIA VIIIA IIIA IVA VA VIA VIIA 12 Halogens, Group 7-A The most reactive nonmetals: Fluorine, Chlorine, Bromine, Iodine & Astatine. IA IIA VIIIA IIIA IVA VA VIA VIIA 13 Noble Gases, Group 8-A The inert (non-reactive) gases: Helium, Neon, Argon, Krypton, Xenon & Radon. IA VIIIA IIA IIIA IVA VA VIA VIIA 14 Metallic Properties • Silver in color and have luster. • Solid @ Room Temperature. • Have high densities. • Are malleable & ductile. • Are good conductors of heat & electricity. • Atoms have between 1-3 valence electrons. • Atoms have a loose hold on their valence electrons - they give them up easily. • Corrode (rust) in the presence of oxygen. 15 Periodic Trends: Periods and Metallic Properties M o r e M e t a l l i c Less Metallic 16 Periodic Trends: Atomic Radii Radius nucleus valence e- Atom Two variable determine the atomic radius of a atom: the number of protons in the nucleus the number of electron energy levels in the atom. The number protons and radius are inversely proportional. As protons increase, the radius decreases. The number of energy levels and radius are proportional. As energy levels increase, the radius also increases. 17 Atomic Radii of the Elements IA Atomic Radii increases due to an increase in the number of eenergy levels. H VIIIA IIA IIIA IVA VA Mg Al Si P VIA VIIA Li Na S Cl Ar K Rb Cs Atomic Radii decreases due to the increase in the number of protons. 18 Atomic Radii & Protons As you go across a period, the atoms gain protons while the number of electron energy levels remain the same. This increase in the number of protons causes a greater attraction between the nucleus and the electrons in the atom. The electrons are pulled closer the nucleus giving the atom a smaller radius as you go across a period. + + ++ ++ k e y + proton electron Force of Attraction 19 The atomic radii decreases because more protons are added to the nucleus. This causes the electrons to be pulled closer to the nucleus. 20 The energy required to remove an electron becomes greater because there are more protons in the atom (greater attraction). 21 As you go across a period, the valence electrons in the A-groups increase by one. 22 As you go down the Alkali Metals, the valence electrons get further from the nucleus and are easier to remove from the atom. The lower the ionization energy the higher the chemical activity. As you go down the Alkali Metals family, the number of eenergy levels increases. This causes their atomic radii to increase. 23 Alkali Metals: Chemical Activity Li Na K Rb Cs Fr As you go down the Alkali Metal Family the radii of the atoms becomes greater and their hold on the valence electron becomes weaker. Weak hold on valence electron = greater chemical activity. 24 M e t a l l i c p r o p e r t i e s i n c r e a s e Summing Up Periodic Trends E n e r g y l e v e l s i n c r e a s e A t o m i c R a d i i i n c r e a s e s This table is called a Periodic Table because periodic trends occur as you go down families and across periods. Atomic Radii decreases Valence electrons increase Metallic properties decrease Ionization Energy increases We will use these periodic trends to understand how elements combine to form compounds in the next chapter. 25 Periodic Trends: Electronegativity The ability of an atom to attract valence electrons to itself. NonMetal Periodic Trends: Ionization Energy The energy required to remove and electron from an atom. Metal 26