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THE PERIODIC TABLE PERIODIC When something occurs at regular intervals (you can predict what happens / comes next) So what makes the periodic table periodic? ATOMIC NUMBER!!! (across the chart) PERIODIC LAW The properties of the elements are a periodic function of their atomic numbers PERIOD All of the elements in a horizontal row GROUP All of the elements in a vertical column (aka Family) Dmitri Mendeleev (1834-1907) invented the periodic table based on increasing atomic mass …and yes, he too, is your friend Henry Moseley (1913) revised the periodic table based on properties and atomic number …and yes, he too, is your friend ALKALI METALS 1 s group • Good Conductors ALKALINE EARTH METALS 2 s group • Harder, more dense, stronger than alkali TRANSITION METALS d sub energy level • Columns 3-12 LANTHANOID SERIES 4f sub energy level • Z = 57-70 ACTINOID SERIES 5f sub energy level • Z = 89-102 • All have radioactive + °) forms (unstable p & N Columns 13, 14, 15, 16 are named by the first element in the column (e.g. Boron Group) HALOGENS 5 p group • Combine with metals to form salts • Very reactive NOBLE GASES 6 p group • Inert gases (not reactive) • 8 valence electrons Classifications by e Configuration • Noble Gases: p6 • Representative Elements: s or p (not p6) • Transition Metals: “d-block” • Inner Transition Metals: “f-block” Stability of e configurations OCTET The eight outer electrons in an atom FACT: Atoms with full outer energy levels are very stable (less reactive) OCTET RULE If an atom has 8 electrons in its outer energy level, it is unreactive (save He) Pretend we had a subenergy level with 8 electrons. When would it be most stable? (The egg carton example) FACT #2: Atoms with filled, half filled, or empty sub-energy levels are slightly more stable Check out PT on pages 392-393. Look at Cu. What is the e configuration? [Ar] 1 10 4s 3d …why??? The atom is more stable if it has a full “d” sub-energy level and a ½ full “s” subenergy level Check out the PT on page 392-393. Look at Gd. What is the e configuration? [Xe] 2 7 1 6s 4f 5d …why??? To Review…How do we make sub energy levels more stable? Move electrons so SUBENERGY levels are FULL, HALF FULL, or COMPLETELY EMPTY Now…how do we make ENERGY LEVELS more stable? Ways to make full outer energy levels: •Add electrons to a partially filled outer energy level •Lose all electrons in the outer energy level •Share electrons with another atom Periodic Trends ATOMIC RADIUS The distance from the center of the nucleus to the outermost energy level The atomic radius INCREASES within a family (just adding energy levels) The atomic radius DECREASES within a period (more positive charge pulling e-) SHIELDING EFFECT The positive pull is less because the distance between nucleus and electrons is greater IONIZATION ENERGY the energy required to remove an electron from an atom The ionization energy DECREASES as you go down a family (shielding effect) The ionization energy INCREASES across a period (more + p have more pull on e) ELECTRON AFFINITY how much an atom desires another electron The electron affinity DECREASES as you go down a family (shielding effect) The electron affinity INCREASES across a period (except for the noble gases) (more + p have more pull on e) ELECTRONEGATIVITY The tendency of an atom to attract electrons to itself when it is bonded to another atom The electronegativity DECREASES as you go down a family (shielding effect) The electronegativity INCREASES across a period (more + p have more pull on e) WHITEBOARDING Write the electron configuration for Copper WHITEBOARDING Identify all of the elements with deviations in their electron configurations WHITEBOARDING Write the old “normal” electron configuration for Mo, Au, La, Cm. Below each of these write the electron configuration with deviation.