RegulationsforAmericanPupilsandMiddle SchoolStudentsAlways referto ateacher by titleand last nameGettoclassontimeRaise your hand when you want to ask a questionYou mayspeak to theteacherfromyour desk whileyou areseatedWhen you are absent, you must make up the workyouhavemissed.Askeithertheteacherora classmateforthe workIfyou expecttobeawayfromschool becauseofanemergency,tellyourteacherinadvanceandaskforthe work you will missAll assignmentsyou handinmustbeyour ownworkNever cheat on a test
1 Regulations for American Pupils and Middle School Students • Always refer to a teacher by title and last name • Get to class on time • Raise your hand when you want to ask a question • You may speak to the teacher from your desk while you are seated • When you are absent, you must make up the work you have missed. Ask either the teacher or a classmate for the work • If you expect to be away from school because of an emergency, tell your teacher in advance and ask for the work you will miss • All assignments you hand in must be your own work • Never cheat on a test •
Transition elements:thefactsITransition elements: the facts IDEFINITIONSd block element: any element with its highestenergy electron in a d orbitalTransition element: those elements havingions with electrons in an incomplete d shelli.e. from titanium to copperSc3+: [Ar] 3d04s0NodelectronsZn2+:[Ar] 3d10..not transitionalfulldshellsd-block..nottransitionaltransitionelementsCu2+:[Ar]3d9incompletedshellsvTiCrCoNiMnFeCu..transitional2
2 Transition elements: the facts I DEFINITIONS d block element: any element with its highest energy electron in a d orbital Transition element: those elements having ions with electrons in an incomplete d shell i.e. from titanium to copper Transition elements: the facts I
Transition elements: the facts ITYPICALPHYSICALPROPERTES:all metalshigh m.p. chromium 2160K, iron 1800K compared with sodium 371Kharddensebut not titaniumsimilar atomic and ionic sizes and ionization energiesUnlike elements in the s and p blocks, there is little change inatomic and ionic radii as the d block is crossed. This is because theadditional electrons are going into an inner d sub-shell. This alsoresults in only a small increase in ionization energy across the dblock. Although each successive nucleus has one more proton, thisextra positive charge is partly shielded from the outer 4s electronsby the extra d electron in an underlying shell.3
3 Transition elements: the facts I TYPICAL PHYSICAL PROPERTIES: all metals high m.p. chromium 2160K, iron 1800K compared with sodium 371K hard dense but not titanium similar atomic and ionic sizes and ionization energies. Unlike elements in the s and p blocks, there is little change in atomic and ionic radii as the d block is crossed. This is because the additional electrons are going into an inner d sub-shell. This also results in only a small increase in ionization energy across the d block. Although each successive nucleus has one more proton, this extra positive charge is partly shielded from the outer 4s electrons by the extra d electron in an underlying shell
Transition elements:thefactsITYPICALCHEMCALPROPERTIES1.Variable valencyTransition elements show many oxidation states, these fall into twokinds:higher oxidation states:thecovalently bonded oxo-compoundse.g. CrO4?-; Cr,O,2-; MnO4; MnO42-lower oxidation states:theatomicionse.g. Cr3+; Cr2+; Mn3+; Fe3+; Fe2+; Cu?+; Cu*4
4 Transition elements: the facts I 1. Variable valency Transition elements show many oxidation states; these fall into two kinds: ● higher oxidation states: the covalently bonded oxo-compounds e.g. CrO4 2- ; Cr2O7 2- ; MnO4 - ; MnO4 2- ● lower oxidation states: the atomic ions e.g. Cr3+ ; Cr2+ ; Mn3+ ; Fe3+ ; Fe2+ ; Cu2+ ; Cu+ TYPICAL CHEMICAL PROPERTIES
Transition elements: the facts I2. Colored compoundsMany of the compounds of the transition elements are coloredcommonexamples:CrO.2--yellow,Cr3+-green,Cr2+-blue;Cr20,2-orange;chromate(VI)dichromateMnO.?--green;MnO4-purple;Mn?+-pale pink(per)manganate(VII)manganate (VI)Fe3+-yellow; Fe2+-greenCo2+-pink in water, blue when dryCu?+-blue5
5 Transition elements: the facts I 2. Colored compounds Many of the compounds of the transition elements are colored. ● common examples: CrO4 2- -yellow; Cr2O7 2- -orange; Cr3+ -green; Cr2+ -blue; chromate(VI) dichromate MnO4 - -purple; MnO4 2- -green; Mn2+ -pale pink (per)manganate(VII) manganate (VI) Fe3+ -yellow; Fe2+ -green Co2+ -pink in water, blue when dry Cu2+ -blue