Periodic Trends Copyright Sautter 2003

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PERIODIC TRENDS OF THE ELEMENTS CHEMICAL PROPERTIES PHYSICAL PROPERTIES ATOMIC RADII IONIC RADII IONIZATION ENERGY ELECTRON AFFINITY ELECTRONEGATIVITY METALLIC & NONMETALLIC CHARACTER PERIODIC TABLE ? I INVENTED IT ! MENDELEYEV

DEFINITIONS OF PERIODIC PROPERTIES CHEMICAL PROPERTIES REFERS TO THE TENDENCY OF ATOMS TO COMBINE WITH OTHER ELEMENTS AND/ OR MOLECULES TO FORM COMPOUNDS. PHYSICAL PROPERTIES REFERS TO CHARACTERISTICS SUCH AS DENSITY, PHYSICAL STATE (SOLID, LIQUID OR GAS), ELECTRICAL AND THERMAL CONDUCTIVITY, MALLEABILITY (CAN BE HAMMERED INTO SHAPE), DUCTILITY (CAN BE STRETCHED), COLOR, LUSTER (SHININESS), BRITTLENESS, ETC.

DEFINITIONS OF PERIODIC PROPERTIES (CONT’D) ATOMIC RADII IS MEASURED AS ONE HALF OF THE DISTANCE BETWEEN THE NUCLEI OF TWO ADJACENT SIMILAR ATOMS (IT MEASURES ATOMIC SIZE) IONIC RADII IS MEASURED AS ONE HALF OF THE DISTANCE BETWEEN THE NUCLEI OF TWO ADJACENT SIMILAR IONS (IT MEASURES ION SIZE) IONIZATION ENERGY MEASURES THE ENERGY NEEDED TO REMOVE AN ELECTRON FROM A FREE ATOM IN THE GAS STATE (IT MEASURES HOW TIGHTLY ELECTRONS ARE BOUND TO AN ATOM) ELECTRON AFFINITY MEASURES THE ENERGY RELEASED WHEN AN ELECTRON IS ADDED TO A FREE ATOM IN THE GAS STATE ( IT MEASURES HOW WELL ATOMS ATTRACT ELECTRONS)

DEFINITIONS OF PERIODIC PROPERTIES (CONT’D) ELECTRONEGATIVITY MEASURES THE ELECTRON ATTRACTING ABILITY OF AN ATOM WHEN IT IS BONDED TO ANOTHER ATOM METALLIC CHARACTER MEASURES THE TENDENCY OF AN ELEMENT TO ACT AS A METAL IN THINGS SUCH AS CONDUCTIVITY, TENDENCY TO LOSE ELECTRONS, SHININESS, MAEBILITY AND DUCTILITY NONMETALLIC CHARACTER MEASURES THE TENDENCY OF AN ELEMENT TO ACT AS A NONMETAL IN THINGS SUCH NONCONDUCTIVITY, TENDENCY TO GAIN ELECTRONS, LOW LUSTER AND BRITTLENESS.

GENERAL ORGANIZATION OF THE PERIODIC TABLE COLUMNS (FAMILIES) CONTAIN ELEMENTS WITH SIMILAR VALENCE ELECTRON CONFIGURATIONS (ns1, ns2, ns2 np3, ETC.) AND SIMILAR CHEMICAL PROPERTIES ROWS (PERIODS) CONTAIN ELEMENTS WITH VALENCE ELECTRONS AT THE SAME ENERGY LEVEL (n=1, n=2, n=3, ETC.) BLOCKS OF ELEMENTS CONTAIN ATOMS WITH THE SAME VALENCE ELECTRON ORBITAL TYPE (s, p, d OR f)

s B L O C K d BLOCK p BLOCK I N E R T G A S f BLOCK metals non metals METALLOIDS Orbital Blocks on the Periodic Table

COMMON CHEMICAL FAMILES & THEIR PROPERTIES COLUMN I (ALKALI METALS) Li, Na, K, Rb, Cs AND Fr FORM +1 CATIONS ARE HIGHLY METALLIC REACTION READILY AND RAPIDLY WITH WATER TO FORM HYDROXIDES AND HYDROGEN GAS REACT WITH THE HALOGENS (COLUMN VII) TO FORM SALTS WITH FORMULA TYPE MX (FOR EXAMPLE NaCl OR KBr) VALENCE ELECTRONS ARE ns1 COLUMN II (ALKALINE EARTH METALS) Be, Mg, Ca, Ba, Sr AND Ra FORM +2 CATIONS ARE HIGHLY METALLIC REACTION READILY AND RAPIDLY WITH WATER TO FORM HYDROXIDES AND HYDROGEN GAS REACT WITH THE HALOGENS TO FORM SALTS WITH FORMULA TYPE MX2 (FOR EXAMPLE MgBr2 OR BaCl2) VALENCE ELECTRONS ARE ns2

COMMON CHEMICAL FAMILES & THEIR PROPERTIES (CONT’D) COLUMN VII (COLUMN 17 ON SOME PERIODIC TABLES) HALOGENS F2,Cl2, Br2, I2 AND At2 ALL ARE DIATOMIC ELEMENTS (OCCUR AS A MOLECULE CONSISTING OF TWO ATOMS ARE HIGHLY NONMETALLIC REACT READY AND RAPIDLY WITH METALS TO FORM SALTS OCCUR IN ALL THREE PHASES AT ROOM TEMPERATURE F2 AND Cl2 ARE GASES, Br2 IS A LIQUID AND I2 IS A SOLID VALENCE ELECTRONS ARE ns2 np5

COMMON CHEMICAL FAMILES & THEIR PROPERTIES (CONT’D) COLUMN VIII (COLUMN 18 ON SOME PERIODIC TABLES) INERT GASES, ALSO CALLED NOBLE GASES OR RARE GASES ALL ARE UNREACTIVE UNDER ORDINARY CONDITIONS ALL HAVE COMPLETED OUTER ENERGY LEVELS ALL ARE GASES AT ROOM TEMPERATURE AND PRESSURE THEIR ELECTRON CONFIGURATIONS ( ns2 np6 ) SET THE STANDARD FOR CHEMICAL STABILITY WHICH MOST OTHER ELEMENTS ATTEMPT TO ACHIEVE THROUGH CHEMICAL REACTION.

C C O O L L M M U U N N I II Transitional Metals C O L M U N V I I I N E R T G A S E S LANTHANIDE SERIES ACTINIDE SERIES Alkali metals Alkaline Earth Metals Halogens CHEMICAL FAMILIES

Valence Electron Orbital Populations Alkali Metals Columun I ns1 np Alkaline Earth Metals Column II ns2 Aluminum Group Column III np1 Carbon Group Column IV np2 Nitrogen Group Column V np3 Oxygen Group Column VI np4 Halogens Column VII np5 Noble Gases Column VIII np6 Li thru Cs Be thru Ra B thru Ti C thru Pb N thru Bi O thru Po F thru At Ne thru Rn

WHAT FACTORS DETERMINE THE PERIODIC TRENDS OF THE ELEMENTS ? (1) THE NUMBER OF PROTONS AND ELECTRONS AN ATOM CONTAINS (MORE PROTONS CREATE A GREATER NUCLEAR CHARGE WHICH ATTRACTS ELECTRONS MORE STRONGLY (2) DISTANCE SEPARATING THE OUTER ELECTRONS (VALENCE ELECTRONS) AND THE NUCLEUS (WHEN ELECTRONS ARE CLOSER TO THE NUCLEUS THEY ARE HELD MORE TIGHTLY) (3) PAIRING OF ELECTRONS IN THE OUTER ENERGY LEVEL ORBITALS (PAIRED ELECTRONS ARE MORE STABLE THAN UNPAIRED ELECTRONS)

FACTORS WHICH DETERMINE THE PERIODIC TRENDS OF THE ELEMENTS (CONT’D) (4) THE SYMMETRY OF OUTER ENERGY LEVEL ORBITAL POPULATIONS (GREATER SYMMETRY OF ELECTRON POPULATIONS GIVES MORE STABILITY) (5) PROXIMITY OF OUTER ENERGY LEVEL ORBITALS TO EACHOTHER (WHEN ORBITALS ARE CLOSE TO EACHOTHER IN ENERGY THE ORDER OF ORBITAL FILLING MAY CHANGE. THIS IS ESPECIALLY TRUE FOR THE TRANSITATIONAL ELEMENTS) (6) THE EXTENT TO WHICH THE OUTER ENERGY LEVEL IS FILLED (ATOMS ATTEMPT TO BECOME ISOELECTRONIC WITH THE NEAREST INERT GAS BY GAINING OR LOSING ELECTRONS, WHICH EVER IS EASIEST)

FACTORS THAT DETERMINE THE PERIODIC TRENDS – ATOMIC RADII AAS WE MOVE ACROSS A ROW (PERIOD) FROM LEFT TO RIGHT ON THE PERIODIC TABLE, ATOMS BECOME SMALLER AS THE ATOMIC NUMBER BECOMES LARGER. THIS INCREASE IN NUCLEAR CHARGE ALLOWS THE NUCLEUS TO PULL IN THE ELECTRONS MORE TIGHTLY AND THEREBY REDUCE ATOMIC SIZE (RADIUS). AAS WE MOVE DOWN A COLUMN ON THE PERIODIC TABLE, ELEMENTS CONTAIN MORE ELECTRONS AND MORE ENERGY LEVELS BECOME POPULATED RESULTING IN AN INCREASE IN ATOMIC SIZE (RADIUS). REMEMBER THAT COMPLETING A PERIOD ON THE PERIODIC TABLE RESULTS IN A COMPLETED ENERGY LEVEL WITHIN THE ATOM !

TRENDS OF THE ELEMENTS ONTHE PERIODIC TABLE (ATOMIC RADII) SIZE OF ATOMS DECREASES S I Z E I N C R E A S E S

FACTORS THAT DETERMINE THE PERIODIC TRENDS – IONIC RADII MMETAL ATOMS LOSE ELECTRONS TO BECOME ISOELECTRONIC WITH THE INERT GASES. ALKALI METALS (COLUMN I) FOR EXAMPLE NEED LOSE ONLY ONE ELECTRON TO BECOME ELECTRONICALLY LIKE THE NEAREST NOBLE GAS.THIS IS MUCH EASIER THAN GAINING SEVEN OR MORE ELECTRONS. ALKALINE EARTH METALS NEED TO LOSE ONLY TWO ELECTRONS TO ACHIEVE THE ISOELECTRONIC STATE.THIS IS MUCH EASIER THAN GAINING SIX OR MORE ELECTRONS BBY CONSTRAST, NONMETALS GAIN ELECTRONS TO BECOME ISOELECTRONIC WITH THE INERT GASES. HALOGENS (COLUMN VII) NEED TO GAIN ONLY ONE ELECTRON TO ACHIEVE THE ISOELECTRONIC STATE. THIS IS MUCH EASIER THAN LOSING SEVEN OR MORE ELECTRONS. THE OXYGEN GROUP(COLUMN VI) NEEDS ONLY TO GAIN TWO ELECTRONS AGAIN EASIER THAN LOSING SIX OR MORE ELECTRONS.

FACTORS THAT DETERMINE THE PERIODIC TRENDS – IONIC RADII (CONT’D) WWHEN POSITIVE IONS ARE FORMED BY THE METALS, ELECTRONS ARE LOST AND THE IONS ARE ALWAYS SMALLER THAN THE ATOMS FROM WHICH THEY ARE FORMED. WWHEN NEGATIVE IONS ARE FORM BY THE NONMETALS, ELECTRONS ARE GAINED. THE NUMBERS OF PROTONS IN THE NUCLEUS REMAINS UNCHANGED. THEREFORE FEWER POSITIVE CHARGES (PROTONS) HOLD MORE NEGATIVE CHARGES (ELECTRONS) LESS TIGHTLY AND THE ION “BALLOONS” TO A LARGER SIZE. ANIONS ARE ALWAYS LARGER THAN THE ATOMS FROM WHICH THEY ARE FORMED AANIONS IN THE SAME PERIOD ARE LARGER THAN CATIONS IN THAT ROW. THE MORE NEGATIVE THE ANION, THE LARGER IT IS!

FACTORS THAT DETERMINE THE PERIODIC TRENDS – IONIC RADII (CONT’D) Na+1 IONS HAVE ONLY 2 FILLED ENERGY LEVELS K+1 IONS ARE LARGER AND REQUIRE 3 FILLED ENERGY LEVELS +11 2e 8e +19 2e 18e 8e

FACTORS THAT DETERMINE THE PERIODIC TRENDS – IONIC RADII (CONT’D) +9 2e 8e +7 2e 8e F-1 ION HAS 9 PROTONS HOLDING 10 ELECTRONS A 9 p+ TO 10 e- RATIO N-3 ION HAS ONLY 7 PROTONS HOLDING 10 ELECTRONS A 7 p+ TO 10 e - RATIO ELECTRONS ARE HELD LESS TIGHTLY & THE ION ENLARGES

TRENDS OF THE ELEMENTS ONTHE PERIODIC TABLE (IONIC RADII) SIZE OF IONS INCREASES S I Z E I N C R E A S E S

FACTORS THAT DETERMINE THE PERIODIC TRENDS – IONIZATION ENERGIES Na ATOMS HAVE 1 VALENCE ELECTRON IN ENERGY LEVEL 3 K ATOMS ARE LARGER AND HAVE 1 VALENCE ELECTRON IN ENERGY LEVELS 4, FURTHER FROM THE NUCLEUS & MORE EASILY REMOVED +11 2e 8e +19 2e 1e 8e 1e 18e

FACTORS THAT DETERMINE THE PERIODIC TRENDS – IONIZATION ENERGIES (CONT’D) +9 2e 7e +11 2e 8e 1e F HAS 9 ELECTRONS IT IS EASIER TO GAIN 1 ELECTRON AND BECOME ISOELECTRONIC WITH NEON RATHER THAN TO LOSE NONMETALS HAVE HIGH IE 7 ELECTRONS TO BECOME ISOELECTRONIC WITH He Na HAS 11 ELECTRONS IT IS EASIER TO LOSE 1 ELECTRON AND BECOME ISOELECTRONIC WITH NEON RATHER THAN GAIN 7 ELECTRONS TO BECOME ISOELECTRONIC METALS HAVE LOW IE WITH ARGON

FACTORS THAT DETERMINE THE PERIODIC TRENDS – IONIZATION ENERGIES (CONT’D) (1) WHEN ATOMS CONTAIN FEW VALENCE ELECTRONS (METALS – RIGHT SIDE OF THE PERIODIC TABLE), THEY ARE EASILY LOST IN ORDER TO ATTAIN COMPLETED SHELL CONFIGURATIONS AND IONIZATION ENERGY IS LOW AS COMPARED TO ATOM WITH MANY VALENCE ELECTRONS (NONMETALS – LEFT SIDE OF THE PERIODIC TABLE) (2) WHEN ELECTRONS ARE PAIRED IN AN ORBITAL, STABILITY IS INCREASED AND THE IONIZATION ENERGY IS HIGHER THAN FOR AN UNPAIRED ELECTRON IN THE SAME ORBITAL AT THE SAME ENERGY LEVEL.

FACTORS THAT DETERMINE THE PERIODIC TRENDS – IONIZATION ENERGIES (CONT’D) (3) WHEN ORBITAL POPULATIONS ARE SYMMETRICAL (ALL HALF FILLED p OR d ORBITALS) ELECTRONS ARE HARDER TO REMOVE AND IONIZATION ENERGY IS LARGER (4) REGARDING ATOMS WITH ELECTRONS OF SIMILAR CONFIGURATION (PAIRED VS UNPAIRED, METAL VS. NONMETAL) THOSE WITH ELECTRONS AT HIGHER ENERGY LEVELS HAVE LOWER IONIZATION ENERGIES. (5) WHEN THE OUTER ENERGY LEVEL IS COMPLETE, ATOM BECOME HIGHLY STABLE AND IONIZATION IS GREATLY INCREASED.

FACTORS THAT DETERMINE THE PERIODIC TRENDS – IONIZATION ENERGIES (CONT’D) (6) ONCE AN ELECTRON HAS BEEN REMOVED FROM AN ATOM THE REMOVING OF ADDITIONAL ELECTRONS BECOMES MORE AND MORE DIFFICULT. THIS MEANS THAT NO MATTER WHAT THE ELECTRON CONFIGURATION OF AN ATOM MIGHT BE, THE FIRST IONIZATION ENERGY IS ALWAYS LESS THAN THE SECOND IONIZATION ENERGY WHICH IN TURN IS ALWAYS LESS THAN THE THIRD ETC. FOR THAT PARTICULAR ATOM.

FACTORS THAT DETERMINE THE PERIODIC TRENDS – IONIZATION ENERGIES (CONT’D) ALUMINUM Al Al+ Al++ Al+++ 1S 2S 2PX PY PZ 3S 3PX PY PZ LOW 1ST IE (NO PAIRED ELECTRONS) 2ND IE SLIGHTLY HIGHER (PAIRED ELECTRONS) 3RD IE HIGHER THAN 2ND DUE TO MORE PROTON ATTRACTION A COMPLETED OUTER ENERGY LEVEL – ION IS NOW STABLE

TRENDS OF THE ELEMENTS ONTHE PERIODIC TABLE (IONIZATION ENERGY) ACROSS EACH ROW (PERIOD) IE INCREASES D I O E W N D E A C R C E O A L S U E M S N

SUCCESSIVE IONIZATION ENERGIES OF SEVERAL ELEMENTS NOTICE THE RELATIONSHIP BETWEEN ELECTRON PAIRING, ENERGY LEVEL COMPLETIONS AND IE CHANGES

FACTORS THAT DETERMINE THE PERIODIC TRENDS – ELECTRON AFFINITY ELEMENTS WHICH ARE MORE NONMETALLIC (TO THE LEFT & UP ON THE PERIODIC TABLE) HAVE GREATER ELECTRON AFFINITY. THOSE WHICH ARE MORE METALLIC (TO THE RIGHT & DOWN ON THE PERIODIC TABLE) HAVE LOWER ELECTRON AFFINITY.

TRENDS OF THE ELEMENTS ONTHE PERIODIC TABLE (ELECTRON AFFINITY) ACROSS EACH ROW (PERIOD) ELECTRON AFFINITY INCREASES D I O E W N D E A C R C E O A L S U E M S N

FACTORS THAT DETERMINE THE PERIODIC TRENDS – ELECTRONEGATIVITY LIKE ELECTRON AFFINITY, ELEMENTS WHICH ARE MORE NONMETALLIC (TO THE LEFT & UP ON THE PERIODIC TABLE) HAVE GREATER ELECTRONEGATIVITY. THOSE WHICH ARE MORE METALLIC (TO THE RIGHT & DOWN ON THE PERIODIC TABLE) HAVE LOWER ELECTRONEGATIVITY. FLOURINE HAS THE HIGHEST ELECTRONEGATIVITY VALUE OF 4.0 CESIUM HAS THE LOWEST ELECTRONEGATIVITY VALUE OF 0.7.

TRENDS OF THE ELEMENTS ONTHE PERIODIC TABLE (ELECTRONEGATIVITY) ACROSS EACH ROW (PERIOD) ELECTRONEGATIVITY INCREASES D E O N W N D E A C R C E O A L S U E M S N

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