NIS – CHEMISTRY

1. NIS – CHEMISTRY Lecture 27 PeriodicTable OzgurUnal

2. Periodicity in MusicalNotes Trytoidentifytheperiodicity in themusicalnotes.

3. Development of thePeriodicTable Theperiodicity in themusicalnotes is similartotheone in thearrangement of theelements. Thechemicalproperties of elementsrepeatevery 8th element. Thisperiodicitywasdiscovered in the 19th century. • Scientiststhatcontributedtothedevelopment of thearrangement of elements: • John Newlands (1837-1898) • LotharMeyer (1830-1895) • DmitriMendeleev (1834-1907) • Henry Moseley (1887-1915)

4. Development of thePeriodicTable Inthelate 1700s, AntoineLavoisier(1743-1794) compiled a list of elementsknown at the time (33 elements). Theadvent of electricityandspectrometer, newelementswerediscovered. By 1870, therewerearound 70 knownelements • Inordertostudyeachother’sworkeasily, chemistsstartedtodeterminetheatomicmass of elements in 1860. • In 1864, JohnNewlandsproposed an organisationalschemefortheelements. • Hediscoveredthatchemicalproperties of elementsrepeatedevery 8th element. • Law of octaves.. • Figure 6.1

5. Development of thePeriodicTable In 1869, MeyerandMendeleev demonstrated a connection betweenatomicmassand elementalproperties, independently. Theyarrangedtheelements in order of increasingmass. Mendeleev’stablebecame widelyacceptedbecause it predictedundiscovered elements.

6. Development of thePeriodicTable In 1913, Henry Moseleydiscoveredthatatoms of each element contain a uniquenumber of protons in theirnuclei. Moseleyarrangedtheelementsaccordingtotheiratomicnumber. His arrangementresulted in a clearperiodicpattern of properties. Thestatementthatthere is a periodic repetition of chemicalandphysicalproperties of theelementswhentheyarearrangedby increasingatomicnumber is calledthe periodiclaw. Table 6.2

7. The Modern PeriodicTable The modern periodictableconsists of boxes. Eachboxcontains an element’s name, symbol, atomicnumberandatomicmass. Theboxesarearranged in order of increasingatomicnumber. Rowsarecalledperiods. Thereare 7 periods. Columnsarecalledgroups. Eachgroup is numbered 1 through 18. Theelements in groups 1, 2 and 13 to 18 possess a widerange of chemicalandphysicalproperties. Theyarecalledrepresentativeelements. Theelements in groups 3 to 12 arecalledtransitionelements.

8. The Modern PeriodicTable

9. The Modern PeriodicTable Elementsareclassified as metals, non-metalsandmetalloids. Metals: Shinywhensmoothand clean Solid at roomtemperature Goodconductors of electricityandheat. • Thegroup 1 elements (exceptfor H) areknown as thealkali metals. • Alkali metalsaresoreactiveandtheyexist as compoundswithotherelements. • Example:Sodium, Li

10. The Modern PeriodicTable • Thetransitionelementsaredividedintotransitionmetalsandinnertransitionmetals. • Thetwosets of innertransitionmetals, known as lanthanideseriesandactinideseries, arelocatedalongthebottom of theperiodictable. • The rest of theelements in groups 2 t o12 makeupthetransitionmetals. • Example:Titanium Thealkaline earthmetalsare in group 2. Theyarealsohighlyreactive. Example: Calcium, magnesium

11. The Modern PeriodicTable

12. The Modern PeriodicTable Non-metals: Non-metalsareelementsthataregenerallygasesorbrittle, dulllookingsolidslocated on theupperrightside of theperiodictable. Bromine is theonlynon-metal liquid at roomtemperature. Highlyreactivegroup 17 elementsarecalledhalogens. Example: Fluorine Extremelyunreactivegroup 18 elementsarecallednoblegases. Example: Neon, Argon

13. The Modern PeriodicTable Metalloids: Elementsborderingthestairstepline in theperiodictable. Metalloidshavephysicalandchemicalproperties of bothmetalsandnon-metals. Example: Silicon, Germanium

14. NIS – CHEMISTRY Lecture 28 Classification of theElements OzgurUnal

15. ElectronConfiguration Writingoutelectronconfigurationusingaufbaudiagram can be tedious. It is possibletodetermine an atom’selectronconfigurationanditsnumber of valence electronsfromitsposition on theperiodictable. • Theenergylevel of an element’s valence electronsindicatestheperiod on theperiodictable in which it is found. • Example: Gallium[Ar] 4s2 3d10 4p1 is in period4. • Valence electrons of therepresentativeelementstell us thegroupnumber of thoseelements. • Example:Group 1 elementshave 1 valence electron.

16. The s-, p-, d- and f-BlockElements Theperiodictable is dividedintosections, orblocks, accordingtothesublevelsfilledby valence electrons.

17. The s-, p-, d- and f-BlockElements s-BlockElements: s-Blockelementsconsist of groups 1 and 2. Group 1 elementshavepartiallyfilled s-orbitalsby valence electrons: s1 Group 2 elementshavecompletely filleds-orbitalsby valence electrons: s2

18. The s-, p-, d- and f-BlockElements p-BlockElements: After s sublevel is filled, the valence electronsnextoccupythe p sublevel. The p-block, comprised of groups 13 through 18, containselementswithfilledorpartiallyfilled p-orbitals. The p-blockspans 6 groupsbecause the3 p orbitals can hold a maximum of 6 electrons. s and p-blockscomprisethe representativeelements.

19. The s-, p-, d- and f-BlockElements d-BlockElements: The d-blockcontainsthetransitionmetalsand is thelargest of theblocks. Thereare 10 groups in d-block, because d orbitals can have a maximum 10 electrons. Example: Titanium[Ar] 4s2 3d2

20. The s-, p-, d- and f-BlockElements f-BlockElements: The d-blockcontainstheinnertransitionmetals. Thereare 14 groups in d-block, because d orbitals can have a maximum 14 electrons. Itselementsarecharacterizedbyfilledorpartiallyfilled s-orbital, andfilledor partiallyfilled 4f and 5f orbitals.

21. The s-, p-, d- and f-BlockElements Example: Strontium, which is usedtoproduceredfireworks, has an electronconfiguration of [Kr] 5s2 . Withoutusingtheperiodictable, determinethegroup, periodandblock of Strontium. • Strontium[Kr] 5s2 • s2indicatesStrontium’s valence electronsfill s-orbital. ThereforeStrontium in thes-block. • Thereare 2 valence electrons in 5s orbital. Therefore, Strontium is in group 2. • 5 in the 5s2indicatesthatStrontium is in period 5.