Slide 1

Chapter 7 - Periodicity and the Periodic Table

1778 Diderot's Alchemical Chart of Affinities

1789 Antoine Lavoisier produced the first modern list of chemical elements, containing among others, the 23 elements of those known.redefined the term "element". Previously, the metals except mercury were not considered elements.

1808 John Daltons list of elements

1862 Telluric Helix or ScrewFrench geologist , Alexandre-mile Bguyer de Chancourtois

Law of OctavesJohn Newlands(1865)

noticed a repeating pattern of physical and chemical properties every eight elementsreminded him of musical scaleapplied to lower atomic weight elements but not the larger atomic weight elements

never accepted as a law

Periodic lawDmitri Mendeleevpublished(Principles of Chemistry) in 1869one year before Julius Lothar Meyer(although he started his research about 5 years before Mendeleev)

created a list of physical and chemical prop.I began to look about and write down the elements with their atomic weights and typical properties, analogous elements and like atomic weights on separate cards, and this soon convinced me that the properties of elements are in periodic dependence upon their atomic weights. --Mendeleev, Principles of Chemistry, 1905, Vol. II

Mendeleevs table organized by: atomic mass/weight(columns)properties(rows)

contained elements that had yet to be discoveredeka-aluminum = gallium(68)eka-silicon = germanium(70)eka-boron = scandium(45)possible mistake with Te(128) and I(127)???

1870 Baumhauers spiral

1886 Crookes periodic table

1893 Rangs periodic table

1898 Crookes 3-D periodic table

Moseley discovers atomic # (1915)periodic law is revised the chemical and physical prop. of the elements are a periodic function of an increasing atomic #

period rows on periodic table

groups/families columns on periodic tablesimilar e- configurationvalence e- - electrons in highest NRG levelmaximum of 8 e-

main group elementss and p block elements

group 1 Alkali metals

group 2 Alkaline Earth metals

groups 3 thru 6new numbering 13 - 16no particular namesproperties vary from metallic to nonmetallic

metalsexcellent conductor of electricity100,000x better than nonmetalsshiny/luster*good conductor of heat*ductile*drawn out in to thin wiremalleable*hammered in to thin sheetstenacious*resist being pulled aparthigher melting and boiling pts** varies among metalsnonmetalspoor conductors of electricityinsulatorspoor conductors of heatmany dull in appearancemost are brittlelower melting and boiling pts

metalloidshave properties of both metals and nonmetalslocated along stair step line separating metals from nonmetals

Halogens group 7(17)most reactive nonmetalsrequire 1 e- to fill outer NRG levelreact with most metals to form saltshalogen(Greek) salt maker

transition metalsd-orbital electronsloosely held by nucleusgood elect. conductorsvery malleablelast electrons are in various NRG levelssome e- config vary from aufbau principlemay lose 1, 2 or 3 e- Fe, Cu, Ag

noble gases(inert gases) group 8(18)non-reactiveonly Xe forms a compoundfull outer NRG levelstable e- configuration

rare earth elementslanthanide seriesshiny metalssimilar to alkaline earth metalsactinide seriesunique nuclear structureall are radioactive

hydrogenmost abundant element in universe75% of all atoms are Hnot in any group1 p+ and 1 e- allows for H to bond with many of the elementsthree isotopesprotium(H-1) 1 p+ , 1 e- , 0 no deuterium(H-2) 1 p+ , 1 e- , 1 no tritium(H-3) 1 p+ , 1 e- , 2 no

7.12 Periodic Trends trend a predictable change in a particular directiontypically restricted to main group elementsatomic radiushalf the distance between two bonded adjacent nuclei

periodic trendin a group, as atomic # increases atomic radii increasesvalence e- in higher NRG levelsmore electron shieldinge- shielding blockage of the nuclear charge from reaching outer most e- by inner NRG level e-

in a period, as atomic # increases atomic radii generally decreasese- in same NRG levele- shielding constantgreater nuclear charge

ionization NRGNRG added to an atom to overcome the attractive forces holding the e- around the nucleusNRG required to remove an e- from an atomX + ion. NRG X+ + e-

Na + ion. NRG Na+ + e-

Br + ion. NRG Br+ + e- creates charged atoms = ions

in a group, as atomic # increases ionization NRG decreaseslarger atomsmore e- shieldingless nuclear attraction for outermost e- less NRG required to remove e- Li > Na > K > Rb > Cs > Frin a period, as atomic # increases ionization NRG generally increasesatoms are smallere- shielding constantgreater nuclear attractionmore NRG required to remove e- Na < Mg < Al < Si < P < S < Cl < Ar

metals tend to lose e- oxidation a chemical reaction in which a substance gains a more positive charge by losing e- Na Na+ + e- = oxidationNa = 11p+ & 11e- Na+ = 11p+ & 10e-

= LEOelectronegativitythe attraction an atom has for other atoms e- arbitrary scaleF is most electronegative = 4other elements based on attraction of Fperiodic trendin a group, as at. # increases, electronegativity decreasesless attraction due to larger atoms and e- shieldingin a period, as at. # increases, electronegativity increasesgreater nuclear attractionmost electronegative = upper right corner Fleast electronegative = lower left corner Fr

e- affinityNRG change associated with the addition of an e- to an atompositive e- affinity(exothermic)X + e- X- + NRGmost elementsCl + e- Cl- + NRGnegative e- affinity(endothermic)X + e- + NRG X- few elementsalkaline earth metals, noble gases, zn-subgroupfull orbitalsCa + e- + NRG Ca- periodic trendpositive e- affinity(only)in a group, as atomic # increases, NRG released decreasesless nuclear attraction for the e- in a period, as atomic # increases, NRG released increasesgreater nuclear attraction for the e-

nonmetals tend to gain e- reduction a chemical reaction in which a substance gains e- and becomes more negatively chargedCl + e- Cl- Cl = 17p+ & 17e- Cl- = 17p+ & 18e-

LEOsays GERionic sizesize of ion after the atom has lost or gained e- cations positive ionscreated when metals lose e- Na + NRG Na+ + e- smaller than their atomsize varies with # of e- lostanions negative ionscreated when nonmetals gain e- Cl + e- Cl- + NRGlarger than their atomsize varies with # or e- gained

melting and boiling pointsmelting point - the temperature at which a solid changes to a liquidboiling point the temperature(at normal pressure) at which a liquid changes to a gasperiodic trend(transition metals only)generally, melting and boiling points are directly related to the # of unpaired e- in an orbitalmore unpaired e- the higher the melting and boiling pts.

other elements dependent on various other factors