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Ch 5 Periodic Table 1 2 Periods Rows are called periods. Period number indicates the highest occupied energy level of the electrons. The two named periods are the lanthanide and actinide series found at the bottom of the periodic table. 3 Lanthanide and Actinide Series These two periods of elements are broken apart from the rest due to the fact that are man-made. Lanthanides are shiny metals that are not very reactive. Actinides are all radioactive metals and are somewhat reactive. 4 Groups Columns are called groups. Each group consists of a specific family of elements that share similar properties. These families include Alkali Alkaline Transition Halogen Noble gas 5 Alkali Family Alkali metals belong to group 1. They are soft, silvery metals with a low melting point. They are the most reactive metal group. Their normal state of matter is solid. 6 Alkaline Family Alkaline metals belong to group 2. They are harder, denser, and have a higher melting than alkali metals. They are only slightly less reactive. Their normal state of matter is solid. 7 Transition Family Transition metals belong to group 3-12. They have typical metal properties such as a very high luster and good conduction. They are so unreactive that they normally exist in nature as lone elements. Their normal state of matter is solid. 8 Halogen Family Halogens belong to group 17. They are the most reactive nonmetal group. They typically react with metals to form salts. The normal states of these elements include two solids, one liquid, and two gases. 9 Noble Gas Family Noble gases belong to group 18. They are unreactive nonmetals. They normally exist in nature as lone elements. Their normal state of matter is gas. 10 11 Trends The periodic table is arranged in a very organized way with distinct patterns. It can offers many clues that may be helpful through this class. Some of the periodic trends include: Valence electrons Oxidation numbers Reactivity Sates of matter Metallic properties Energy level blocks Ionization energy Atomic radii Ionic radii Electronegativity 12 Valence Electrons Valence electrons are the outer electrons available to be lost, gained, or shared when bonding. The last digit in the group number indicates the number of valence electrons. 13 Oxidation Numbers Oxidation number is the number assigned to an atom in an ionic compound. It indicates the number of electrons and how the electrons are used while bonding. It proceeds across the groups starting at group 1, skipping over transition elements, and ending at group 18. The numbers are: +1, +2, +3, +4, -3, -2, -1, 0. Elements with positive oxidation numbers lose the specified amount of electrons to form positive cations. Elements with negative oxidation numbers gain the specified amount of electrons to form negative anions. 14 Reactivity Reactivity increases as you go down a metallic group. Reactivity decreases as you go down a nonmetallic group. 15 States of Matter With the exception of hydrogen, solids are located on the left of the periodic table and gases on the right. The only two liquids are mercury (a liquid metal) and bromine (a liquid nonmetal). 16 Metallic Properties There is a stair step line that divides the periodic table into metals and nonmetals. Everything to the left of the line is a metal and everything to the right is a nonmetal. With the exception of aluminum (a metal), everything touching the line is a metalloid. A metalloid shares characteristics of both metals and nonmetals and exist as very brittle solids. 17 18 Energy Level Blocks Groups are divided into blocks based on sublevels. There is an s-block, p-block, d-block, and f-block. S-block is group 1 and 2. Group 1 electron configurations end with ns1, group 2 end with ns2. P-block is group 13 through 18. Electron configurations proceed as np1, np2, np3, np4, np5, and np6. The n in each electron configuration indicates the main energy level and can be found from the period number. D-block is group 3-12. At this block electron configuration rules have to be followed closely and there is no general trend. F-block does not belong to any groups. Rather, it belongs to period 8 and 9, the lanthanide and actinide series. 19 Blue= s block Yellow= p block Red= d block Green= f block 20 Ionization Energy Ionization energy is the energy required to remove one electron from a neutral atom to form an ion. The trends are: Increase across a period Decrease down a group IE increases with each successive ionization 21 Electronegativity Electronegativity is a measure of the ability of an atom to attract electrons. The trends are: Increase across period Decrease down a group 22 Atomic Radii Atomic radii is a measurement of half the distance between the nuclei of two identical atoms that are bonded. The trends are: Decrease across a period Increases down a group 23 Ionic Radii Ionic radii is the radius of an ion formed by the element. Group 1-14 have positive oxidation numbers and therefore lose electrons to form cations. Formation of a positive cation causes decrease in size from atomic radii. Group 15-18 have negative oxidation numbers and therefore gain electrons to form anions. Formation of a negative anion cause increase in size from atomic radii. 24