Izinkambiso zethebula lezikhathi: umthwalo wenyukliya osebenzayo, usayizi namandla

Umthwalo wenyukliya osebenzayo nokuvikela

I-electron yangaphandle ayizizwa umthwalo wonke wenyukliya Z. Ama-electron asondele kunyukliya awukhansela ngokwengxenye, futhi ukudonsa okungenayo kuchazwa umthwalo wenyukliya osebenzayo, Zeff = Z − S, lapho u-S eyisilinganiso sokuvikela. Ama-electron omongo, ezinqakeni eziphansi, avikela kahle. Ama-electron e-shell efanayo avikela kabi, ngoba ngokwesilinganiso akasondele kunyukliya kune-electron okukhulunywa ngayo.

Isilinganiso esikhulu sibala ama-electron omongo kuphela. I-sodium (Z = 11) ne-chlorine (Z = 17) zombili zinama-electron omongo angu-10, ngakho i-electron ye-3s ye-sodium izizwa cishe +1 kanti ama-electron e-3p e-chlorine izizwa cishe +7. Imithetho ka-Slater iyalungisa lokhu. Ku-electron ku-subshell ye-ns noma i-np, i-electron ngayinye enye ku-ns ne-np efanayo yengeza u-0.35 ku-S (0.30 ku-1s), i-electron ngayinye ku-shell n − 1 yengeza u-0.85, futhi i-electron ngayinye ezinqakeni ezijulile yengeza u-1.00.

Isibonelo esisebenzile 1. Ku-electron ye-3s ye-sodium, S = 8(0.85) + 2(1.00) = 8.80, ngakho Zeff = 11 − 8.80 = 2.20. Ku-electron eyodwa ye-3p ye-chlorine, S = 6(0.35) + 8(0.85) + 2(1.00) = 10.90, ngakho Zeff = 17 − 10.90 = 6.10. Phakathi kwesikhathi 3, i-proton ngayinye eyengeziwe ilinganiswa ngokwengxenye kuphela yi-electron eyengeziwe ye-shell efanayo, ngakho u-Zeff uyakhula usuka kwesobunxele uya kwesokudla ngenkathi u-n ehlala ku-3.

Irediyasi ye-athomu nama-ayoni e-isoelectronic

Irediyasi ye-athomu iyancipha phakathi kwesikhathi ngoba u-Zeff uyakhula ngenkathi ama-electron angaphandle ehlala e-shell efanayo, ngakho adonselwa eduze. Iyakhula ngaphansi kweqembu ngoba isikhathi ngasinye sengeza i-shell, sibeka ama-electron angaphandle kude, kuyilapho u-Zeff eshintsha kancane uma kuqhathaniswa. Ama-athomu amakhulu kakhulu aphansi ngakwesobunxele kwethebula kanti amancane kakhulu aphezulu ngakwesokudla.

I-cation incane kune-athomu yayo yokuqala: ukulahlekelwa ama-electron kunciphisa ukuphikisana, futhi kuma-cation eqembu eliyinhloko ngokuvamile kungenisa i-shell yangaphandle. I-anion inkulu kune-athomu yayo yokuqala, ngoba i-electron eyengeziwe ikhulisa ukuphikisana ngenkathi umthwalo wenyukliya uhlala unjalo.

Isibonelo esisebenzile 2. Hlela u-N³⁻, O²⁻, F⁻, Na⁺, Mg²⁺ no-Al³⁺ ngerediyasi. Bala ama-electron kuqala: 7 + 3, 8 + 2, 9 + 1, 11 − 1, 12 − 2 no-13 − 3 konke kulingana no-10, ngakho i-ayoni ngayinye inokulungiswa kwe-neon 1s² 2s² 2p⁶. Ngenani elifanayo lama-electron, umehluko kuphela umthwalo wenyukliya, ukhula usuka ku-7 uye ku-13. Ama-proton amaningi adonsa ifu elifanayo lama-electron liqine, ngakho ukulandelana ngu-N³⁻ > O²⁻ > F⁻ > Na⁺ > Mg²⁺ > Al³⁺.

Amandla okuqala e-ionization nokuhlukile kwawo kwe-subshell

Amandla okuqala e-ionization angamandla adingekayo ukususa i-electron egodle kancane kunazo zonke e-athomu legesi: X(g) → X⁺(g) + e⁻. Ngokuvamile akhula phakathi kwesikhathi, njengoba u-Zeff ukhula futhi irediyasi incipha, futhi ancipha ngaphansi kweqembu. I-NIST ibhala amandla e-ionization nge-electron volts ngeathomu ngalinye; ukuphindaphinda ngo-96.485 kJ/mol nge-eV ngayinye kuwaguqulela emayunithini e-molar.

Aguqulelwe kusuka ku-NIST Atomic Spectra Database, amanani esikhathi 2 ngu-Li 520.2, Be 899.5, B 800.6, C 1086.5, N 1402.3, O 1313.9, F 1681.0 no-Ne 2080.7 kJ/mol. Izinyathelo ezimbili ziya ngendlela engafanele. I-boron iphansi kuka-beryllium ngoba i-electron yayo yangaphandle ise-2p, ephakeme emandleni futhi ivikelwe ngokwengxenye yibhangqa le-2s. I-oxygen iphansi kuka-nitrogen ngoba i-electron yayo yesine ye-2p kufanele ibhangqe ku-orbital esithathiwe, futhi ukuphikisana okwengeziwe kwenza kube lula ukuyisusa.

Ukwehla okubili okufanayo kuvela esikhathini 3: i-aluminium (577.5 kJ/mol) iphansi kwe-magnesium (737.7 kJ/mol), futhi i-sulfur (999.6 kJ/mol) iphansi kwe-phosphorus (1011.8 kJ/mol). Iphethini ephindiwe ikhombisa ukuthi ivela esakhiweni se-subshell, hhayi kusakhi esisodwa esingajwayelekile.

Amandla alandelanayo e-ionization nama-electron e-valence

Amandla alandelanayo e-ionization ngalinye makhulu kunalelo langaphambilini, ngoba i-electron ngayinye iphuma ku-ayoni eya ngokuya ihle. Usayizi wokweqa ngakunye yilo ulwazi olusizayo. Ukwanda okumaphakathi kusho ukuthi i-electron elandelayo ivela e-shell yevalence efanayo; ukweqa okukhulu kakhulu kusho ukuthi kufanele ivele omongweni, osondele kunyukliya futhi ovikelwe kancane kakhulu.

Isibonelo esisebenzile 3. I-NIST inikeza amandla amathathu okuqala e-ionization e-magnesium ngu-7.646, 15.035 no-80.144 eV. Ukuguqula: 7.646 eV × 96.485 kJ/(mol·eV) = 737.7 kJ/mol; 15.035 × 96.485 = 1450.7 kJ/mol; 80.144 × 96.485 = 7732.7 kJ/mol. Isilinganiso IE₂/IE₁ singu-1450.7 / 737.7 = 1.97, kodwa IE₃/IE₂ singu-7732.7 / 1450.7 = 5.33. Ukweqa okukhulu ngemva kwe-electron yesibili kukhombisa ukuthi i-magnesium inama-electron amabili e-valence, [Ne] 3s², futhi kuchaza ukuthi kungani yakha u-Mg²⁺ kodwa hhayi u-Mg³⁺ ekhemistri evamile.

I-sodium ikhombisa ukweqa isinyathelo esisodwa ngaphambili. Amandla ayo wesibili e-ionization, 4562.4 kJ/mol, cishe aphindwe izikhathi ezingu-9.2 kunawokuqala, 495.8 kJ/mol, ngoba i-electron yesibili kufanele ivele omongweni we-2p.

I-electron affinity ne-electronegativity

I-electron affinity ichaza ushintsho lwamandla lapho i-athomu legesi lizuza i-electron: X(g) + e⁻ → X⁻(g). Izivumelwano zezimpawu ziyahluka. Ezinye izincwadi zokufunda, kuhlanganise ne-OpenStax, zibika ushintsho lwamandla, olungaphansi kuka-zero lapho amandla ekhululwa; ezinye zibika amandla akhululiwe njengenombolo eyisikhwama. Hlola isivumelwano ngaphambi kokuqhathanisa amanani. Ngaphandle kwamagesi aphakeme, ama-athomu ngakwesokudla sesikhathi akhulula amandla amaningi kakhulu, ngoba u-Zeff wawo ophakeme udonsa kakhulu i-electron engenayo.

I-electron affinity ayijwayelekile kangako kunamandla e-ionization. I-chlorine ikhulula amandla amaningi kune-fluorine, cishe 349 kJ/mol uma kuqhathaniswa no-328 kJ/mol, ngokwamanani e-NIST Chemistry WebBook angu-3.613 no-3.401 eV. I-electron eyengeziwe ku-subshell ye-2p encane ye-fluorine ihlangana nokuphikisana okwengeziwe. I-beryllium, i-nitrogen namagesi aphakeme alinakho okuncane noma akunakho ukuthambekela kokwakha ama-anion egesi azinzile, ngoba i-electron eyengeziwe izongena e-subshell ephakeme noma ibhangqe kwegcwele ingxenye.

I-electronegativity yikhono le-athomu emamolekyulini lokudonsa ama-electron esibopho. Ngokungafani namandla e-ionization, ayilinganiswa e-athomu elodwa; ithathwa emandleni ezibopho noma kwenye idatha, futhi isikali sika-Pauling siyona esisetshenziswa kakhulu. I-fluorine iphakeme kakhulu, cishe ku-4.0. I-electronegativity ikhula phakathi kwesikhathi futhi incipha ngaphansi kweqembu, ngakho ubuhlobo besibopho bwehla kusuka ku-H–F kuya ku-H–Cl no-H–Br kuye ku-H–I.

Amaphutha avamile ekuchazeni izinkambiso zethebula lezikhathi

Imibuzo yezinkambiso ivame ukwahlulelwa ngencazelo, hhayi ukulandelana kuphela.

Incazelo ephelele iqamba ukuqhathaniswa (i-shell efanayo noma ehlukile), isho ukuthi kwenzekani ku-Zeff noma ebangeni, futhi ixhuma lolo shintsho nomfutho ku-electron okukhulunywa ngayo.

• Ukusho ukuthi i-athomu incane ngoba inama-electron amaningi. Phakathi kwesikhathi, ama-electron angena e-shell efanayo; usayizi wehla ngoba u-Zeff ukhula.
• Ukuchaza inkambiso yeqembu nge-'ama-shell amaningi' kuphela, ngaphandle kokuqaphela ukuthi u-Zeff ushintsha kancane ngaphansi kweqembu.
• Ukuthatha amandla e-ionization njengokukhula ngokuqinile phakathi kwesikhathi. Hlola izinyathelo zeqembu 2 kuya ku-13 neqembu 15 kuya ku-16.
• Ukuqhathanisa ama-ayoni ngomthwalo wenyukliya ngaphandle kokuhlola kuqala ukuthi ayi-isoelectronic.
• Ukuxuba izivumelwano zezimpawu ze-electron affinity bese uphetha ngokuthi inombolo engaphansi iyi-affinity encane.
• Ukuqhathanisa amarediyasi asuka kumatafula ahlukene. Amarediyasi e-covalent, ensimbi ne-ayoni achazwa ngokuhlukile.
• Ukuchaza ngalokho i-athomu 'elifunayo'. Ama-athomu awanazinhloso; chaza ngokudonsa, ibanga nokuphikisana.