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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.
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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 s1 group • Good Conductors
ALKALINE EARTH METALS s2 group • Harder, more dense, stronger than alkali
d sub energy level TRANSITION METALS • Columns 3-12
4f sub energy level LANTHANOID SERIES • Z = 57-70
5f sub energy level ACTINOID SERIES • 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 p5 group • Combine with metals to form salts • Very reactive
NOBLE GASES p6 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”
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 sub-energy 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] 4s13d10…why???
The atom is more stable if it has a full “d” sub-energy level and a ½ full “s” sub-energy level
Check out the PT on page 392-393. Look at Gd. What is the e- configuration? [Xe] 6s24f75d1…why???
To Review…How do we make sub energy levels more stable? Move electrons so SUB-ENERGY levels are FULL, HALF FULL, or COMPLETELY EMPTY
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
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 ENERGYthe 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-)
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-)
ELECTRONEGATIVITYThe 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-)