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UNIT VIII The Periodic Table and Chemical Bonding Lesson#3 VIII.2 THE PERIODIC TABLE Organized according to ATOMIC # --- Mendeleev Genius! Periodic Law: The chemical properties of the elements recur periodically when the elements are arranged in increasing order by their atomic numbers. A. The Modern Periodic Table INCREASING REACTIVITY METALS Increasing Reactivity Transition METALS Increasing Reactivity Trends in the Periodic Table: PERIOD: is the set of all the elements in a given row going ACROSS the table. [HORIZONTAL] FAMILY (group): is the set of all the elements in a given column going down the table. [VERTICAL] A. The Modern Periodic Table 1 INCREASING REACTIVITY 2 3 4 5 6 7 PERIODS INCREASING REACTIVITY A. The Modern Periodic Table GROUPS VIII.2 THE PERIODIC TABLE Metals, Nonmetals, and Semiconductors: Metals: malleable (flatten into sheets) ductile opaque conduct electricity* solid at room temp (except.... Mercury ) Lustre Shiny-ness *Metals conductivity decreases with an increase in temp TEMP = CONDUCTIVITY VIII.2 THE PERIODIC TABLE Metals, Nonmetals, and Semiconductors: Nonmetals At room temperature: solid, liquid or gas poor conductors Semiconductors aka “metalloids” or “semimetals” conductivity increases with an increase in temp VIII.2 THE PERIODIC TABLE VIII.2 THE PERIODIC TABLE TRENDS: 1. Properties of elements change from metallic to nonmetallic going from left to right More Metallic More Metallic VIII.2 THE PERIODIC TABLE 3. The size of the elements radius INCREASES going across a row and increases going down a family. Atomic Radius INCREASES Atomic Radius INCREASES Why does the size of the element increase going down? Electron Shells Each period on the periodic table represents a different electron shell. The more down you go, the more shells there are. Therefore, the larger the atom’s size (RADIUS) will be. As you go down the periodic table, the atoms get BIGGER WHY DOES THE SIZE OF THE ELEMENT DECREASE GOING ACROSS? FROM LEFT TO RIGHT? Atomic radius explained… Going from left to right on the periodic table, the atomic number increases and the _________ Positive charge on the nucleus increases. Therefore, Attraction between the _____ e- and Positive the __________ ________ increases, causing the radius to nucleus Decrease _____________. As you go across the periodic table, the atoms get SMALLER because….? A. The Electronic Nature of Chemical Bonding Electrostatic Force: Is a force existing as a result of the attraction or repulsion between 2 charged particles + and – ATTRACT (different charges) + and + REPEL – and – REPEL The closer the charges are, the greater the force The greater the charge, the greater the force Na +1 and Cl 1Greater Force Mg 2+ and Br 1- ELECTRON SHELLS OPEN SHELL: is a shell containing less than its maximum number of electrons. O :1s2 2s2 2p4 2 e- CLOSED SHELL: is a shell containing its maximum number of electrons. Ex: noble gases Ar18 : 1S2 2S2 2P6 3S2 3P6 Valence Electrons: Total number of electrons in open shells that can participate in a chemical bond. Use the periodic table to determine the number of valence electrons (for s and p orbitals) Atom K Ca Ga Ge As Se Br Kr Group I 2 3 4 5 6 7 8 # of valence e(e in outter shells) 1 e- 2 e- 3 e- 4 e- 5 e- 6 e- 7 e- 8 eTechnically none are involved in bonding so not really valence electrons CHLORINE AS AN EXAMPLE Draw the valence electrons for Chlorine. Chlorine is in group 7 So…..7 Valence e- Add electrons one at a time in a clockwise fashion. Cl One unpaired bonding e-. Lone Pairs…not involved in bonding VIII.3 CHEMICAL BONDING Valence: The number of unpaired valence electrons on the atom (COMBINING CAPACITY) each ORBITAL holds 2 eonly dealing with s and p orbitals so the maximum number of electrons in a shell is: 2 _______________ e- (s) + 6 e- (p) = 8 e only UNPAIRED electrons take part in bonding! B Group 3…3 e- F Group 7…7 e- VIII.3 CHEMICAL BONDING Going across periodic table the valence of an atom: Group 1 Group 2 Group 3 Group 4 Group 5 Group 6 Group 7 Group 8 1 2 3 4 3 2 1 0 +1 +2 +3 +4 -3 The valence is the combining capacity! -2 -1 0 A few more things to know… Ionization Energy (IE) The minimum energy required to remove an electron from a an atom or molecule in the gaseous state. Ca + energy → Ca2+ + 2e- Neutral Ionization Energy IONIZATION ENERGY Going ACROSS the periodic table the ionization energy (IE) increases Ionization Energy Why? The Electronegativity increases as you go across the periodic table….thus the elements hold onto their electrons more strongly…..thus more energy to pull them away. Ionization Energy Going DOWN the periodic table the IE decreases Why? More energy shells. More energy shells (layers)…thus farther from nucleus (Positively charged)…..thus there is less attraction the farther away you go….so less energy to pull electrons away. Ionization Energy He has the GREATEST ionization energy Fr has the LEAST ionization energy HOMEWORK Pgs 297 – 298 #’s: 1, 4, 5,6 7,11, 12