Qaabdhismeedka atamka iyo isotoobyada: laga bilaabo calaamadaha nukliidka ilaa culeyska atamka

Borotoonnada, niyuutaroonnada iyo elektaroonnada cutubyo la cabbiray

Borotoonku wuxuu sidaa dallacaad +1 ah oo lagu cabbiro cutubyada dallacaadda aasaasiga ah, e = 1.602 × 10⁻¹⁹ C, elektaroonkuna wuxuu sidaa −1. Niyuutaroonku dallacaad ma laha. Culeysyada waxaa badanaa lagu bixiyaa cutubyada culeyska atamka ee midaysan (u, oo sidoo kale loo yaqaan dalton, Da), halkaas oo 1 u uu yahay laba-iyo-tobnaad culeyska atam carbon-12 ah, 1.6605 × 10⁻²⁷ kg.

Marka loo eego qiimayaasha CODATA ee 2022 ee NIST daabacday, borotoonku waa 1.007276 u, niyuutaroonku waa 1.008665 u, elektaroonkuna waa 0.000549 u. Borotoonku wuxuu qiyaastii 1836 jibaar ka culus yahay elektaroonka, sidaa darteed ku dhawaad dhammaan culeyska atamku wuxuu ku jiraa nukliyeerka. Nukliyeerku sidoo kale aad buu u yar yahay: radius-kiisu waa heerka 10⁻¹⁵ m, halka radius-ka atamku yahay heerka 10⁻¹⁰ m. Sidaa darteed elektaroonnadu waxay go'aamiyaan cabbirka atamka iyo kimistarigiisa, nukliyeerkuna wuxuu go'aamiyaa culeyskiisa.

Akhrinta calaamadaha nukliidka iyo tirinta qaybaha ayoonnada

Lambarka atamka Z waa tirada borotoonnada. Wuxuu qeexaa curiyaha: atam kasta oo leh 17 borotoon waa chlorine. Lambarka culeyska A waa wadarta borotoonnada iyo niyuutaroonnada, sidaa darteed tirada niyuutaroonnadu waa A − Z. Calaamadda nukliidku waxay A u qortaa sare-tiro bidix ah, Z-na hoos-tiro bidix ah oo saaran calaamadda curiyaha, sida ³⁵₁₇Cl. Sababtoo ah calaamaddu horey ayay u go'aamisaa Z, hoos-tirada badanaa waa laga tagaa, taasoo bixisa ³⁵Cl ama chlorine-35.

Elektaroonnadu waxay la mid yihiin borotoonnada atam dhexdhexaad ah oo keliya. Ayoon leh dallacaad q wuxuu leeyahay Z − q elektaroon, sidaa darteed dallacaad togan macnaheedu waa elektaroonno ka yar, dallacaad tabanna waa elektaroonno ka badan. Dallacaaddu marnaba ma beddesho nukliyeerka.

Tusaale la xaliyey 1. ⁵⁶Fe³⁺: Z = 26, sidaa darteed 26 borotoon; 56 − 26 = 30 niyuutaroon; 26 − 3 = 23 elektaroon. ¹²⁷I⁻: 53 borotoon, 127 − 53 = 74 niyuutaroon iyo 53 + 1 = 54 elektaroon. ³⁴S²⁻: 16 borotoon, 18 niyuutaroon iyo 18 elektaroon. U fiirso in ³⁴S²⁻ uu leeyahay tirada elektaroonnada ee atam argon ah; tirada elektaroonnada oo isku mid ah ayaa ayoonnada ka dhigta isoelektaroonik, ma aha lambarrada culeyska oo isku mid ah.

Sababta isotoobyadu isugu falgalaan laakiin ugu kala duwan yihiin culeyska

Isotoobyadu waa atamyo leh isla Z laakiin tirooyin niyuutaroon oo kala duwan. Chlorine-35 iyo chlorine-37 labaduba waxay leeyihiin 17 borotoon iyo, marka ay yihiin atamyo dhexdhexaad ah, 17 elektaroon. Dhaqanka kiimikaad waxaa maamula elektaroonnada, sidaa darteed labada isotoob waxay sameeyaan isku-dhisyo isku mid ah oo saamiyo isku mid ah.

Astaamaha ku xiran culeyska way ku kala duwan yihiin wax yar. Molekiyuullada fudud way ka dhaqso badan yihiin heerkul la siiyey, xidhiidhada isotoobyada culusna waxay u falgalaan wax yar oo ka gaabis ah. Saameyntani way yar yihiin curiyayaasha culus. Kobcinta uranium waxay muujinaysaa sida ay u yar yihiin. Marka loo eego sharciga Graham, xawaaraha effusion-ka ee ²³⁵UF₆ iyo ²³⁸UF₆ waxay ku jiraan saamiga √(M₂/M₁). Adigoo isticmaalaya culeysyada isotoobyada NIST, M(²³⁵UF₆) = 349.034 g/mol iyo M(²³⁸UF₆) = 352.041 g/mol, sidaa darteed saamigu waa √(352.041/349.034) = 1.0043. Hal mar oo la dhex maro xayndaab ayaa isotoobka fudud ku kobcisa wax ka yar badh boqolkiiba, taasina waa sababta warshadaha kobcintu ugu baahan yihiin heerar badan oo taxane ah.

Celceliska miisaysan: laga bilaabo culeysyada isotoobyada ilaa culeyska atamka

Culeyska atamka ee shaxda xilliyeedka ku jira ma aha culeyska hal atam. Waa celceliska culeyska atamyada curiyaha ee muunad caadi ah, oo lagu miisaamay sida isotoob kastaa u badan yahay. Ku dhufo culeyska isotoob kasta jajabka baahsanaantiisa oo isku dar wax-soo-saarrada. Jajabyadu waa inay isku geeyaan 1.

Tusaale la xaliyey 2. Magnesium wuxuu leeyahay saddex isotoob oo deggan. Laga soo bilaabo shaxaha NIST ee Atomic Weights and Isotopic Compositions: ²⁴Mg, 23.985042 u, baahsanaan 0.7899; ²⁵Mg, 24.985837 u, 0.1000; ²⁶Mg, 25.982593 u, 0.1101. Wax-soo-saarradu waa 18.94578, 2.49858 iyo 2.86068 u, wadartooduna waa 24.30505 u. Xeerarka adag ee tirooyinka muhiimka ah oo lagu dabaqo baahsanaanta afarta tiro leh waxay tan u dhoweyn lahaayeen 24.31 u. Haddii lagu hayo saddex meelood oo tobanle ah, waa 24.305 u, qiimaha caadiga ah ee ku daabacan inta badan shaxaha xilliyeedka.

Isla xisaabtaas ku samee chlorine, adigoo isticmaalaya ³⁵Cl oo ah 34.968853 u oo baahsanaantiisu tahay 0.7576 iyo ³⁷Cl oo ah 36.965903 u oo leh 0.2424: 26.4924 + 8.9605 = 35.453 u. Qiyaas degdeg ah ayaa qabata khaladaadka: celcelisku waa inuu u dhexeeyaa culeysyada isotoobyada oo uu ugu dhow yahay kan ugu baahsan.

Dib u shaqaynta si loo helo baahsanaanta isotoob

Haddii curiye leeyahay laba isotoob oo aad taqaanno culeyska atamka, waad xallin kartaa baahsanaanta. Jajabka isotoobka koowaad u bixi x; kan labaad markaa waa 1 − x. Celceliska miisaysan u qor isleeg oo u xalli x.

Tusaale la xaliyey 3. Copper wuxuu leeyahay culeys atam caadi ah oo ah 63.546 iyo laba isotoob oo deggan, ⁶³Cu oo ah 62.929598 u iyo ⁶⁵Cu oo ah 64.927790 u (NIST). Markaa 62.929598x + 64.927790(1 − x) = 63.546. Dib-u-habayntu waxay bixisaa x = (64.927790 − 63.546)/(64.927790 − 62.929598) = 1.381790/1.998192 = 0.6915. Sidaa darteed copper waa 69.15% ⁶³Cu iyo 30.85% ⁶⁵Cu, taasoo dib u soo saarta baahsanaanta NIST ee 0.6915 iyo 0.3085.

Habkani wuxuu u shaqeeyaa laba isotoob oo keliya. Saddex isotoob, hal celcelis wuxuu bixiyaa hal isleeg oo leh laba aan la aqoon, waxaadna u baahan tahay cabbir kale, sida spectrum culeys.

Qaababka isotoobyada ee spectrum-ka culeyska

Mass spectrometer-ku wuxuu ionaysiiyaa muunad, wuxuu ayoonnada ku kala saaraa saamiga culeyska iyo dallacaadda, wuxuuna diiwaan geliyaa inta gaarta qiime kasta. Hal curiye, dhererka meelaha sare (peaks) wuxuu si toos ah u bixiyaa baahsanaanta isotoobyada. Molekiyuullada, isotoobyadu way isku darmaan oo waxay soo saaraan qaabab la garan karo.

Tusaale la xaliyey 4. Saadaali qaabka ayoonka molekiyuulka ee Cl₂. Ha ahaato p = 0.7576 ee ³⁵Cl iyo q = 0.2424 ee ³⁷Cl. Molekiyuul wuxuu noqdaa ³⁵Cl–³⁵Cl (culeys 70) iyadoo suurtagalnimadu tahay p² = 0.5740, ³⁵Cl–³⁷Cl (culeys 72) iyadoo suurtagalnimadu tahay 2pq = 0.3673, iyo ³⁷Cl–³⁷Cl (culeys 74) iyadoo suurtagalnimadu tahay q² = 0.0588. Arrinta 2 waxay tirisaa labada siyaabood ee lagu helo mid kasta midkood. Marka la cabbireeyo si peak-ga ugu dheer u noqdo 100, qaabku waa 100 : 64.0 : 10.2.

Laba jid-gaab ayaa ka dhasha. Isku-dhis leh hal atam chlorine ah wuxuu muujiyaa peaks u kala fog laba cutub oo culeys ah oo saamigoodu yahay qiyaastii 3 : 1, sababtoo ah p/q = 3.13. Isku-dhis leh hal atam bromine ah wuxuu muujiyaa laba peak oo dhererkoodu ku dhawaad isku mid yahay, sababtoo ah NIST waxay ⁷⁹Br ku taxdaa 0.5069 iyo ⁸¹Br 0.4931.

Khaladaadka qaabdhismeedka atamka ee dhibcaha lumiya

Khaladaadka badankoodu waxay ka yimaadaan isku qaldidda saddexda tiro ama u qaadashada culeyska atamka astaan hal atam. Qor Z, A iyo dallacaadda kahor intaadan waxba tirin.

• Beddelidda tirada borotoonnada si loo sameeyo ayoon. Dallacaaddu waxay beddeshaa elektaroonnada oo keliya; borotoonnadu waxay go'aamiyaan curiyaha.
• Ku darista elektaroonno ayoon togan. Ayoon 3+ ah wuxuu leeyahay saddex elektaroon oo ka yar atamka.
• U akhrinta culeyska atamka sida lambar culeys. Ma jiro atam chlorine ah oo culeyskiisu yahay 35.45 u; waa celceliska atamyo qiyaastii ah 35 u iyo 37 u.
• U isticmaalidda boqolkiiba sida jajabyo adigoo aan u qaybin 100, taasoo bixisa celcelis 100 jibaar ka weyn.
• Illaawidda arrinta 2 ee lammaanayaasha isotoobyada isku dhafan, sida ³⁵Cl–³⁷Cl, marka la saadaalinayo spectrum culeys.
• Laba nukliid ugu yeedhid isotoobyo sababtoo ah waxay leeyihiin isla lambarka culeyska. ¹⁴C iyo ¹⁴N waxay wadaagaan A laakiin waa curiyayaal kala duwan.

Cilladda culeyska iyo culeysyada atamka ee dhexda ah

Isku darka lix borotoon, lix niyuutaroon iyo lix elektaroon adigoo isticmaalaya culeysyada CODATA wuxuu bixiyaa 12.0989 u, hase yeeshee atam carbon-12 ah waa si sax ah 12 u. 0.0989 u-da maqan, oo qiyaastii ah 0.82% wadarta, waxay u dhigantaa tamarta la sii daayey markii nukliyeerku samaysmay. Cilladdan culeysku waa sababta culeysyada isotoobyadu aysan u ahayn tirooyin dhan, waana barta laga bilaabo tamarta isku-haynta nukliyeerka.

Curiyayaasha qaarkood, isku-dhafka isotoobyadu wuxuu ku kala duwan yahay ilaha dabiiciga ah ilaa heer Guddiga IUPAC ee Baahsanaanta Isotoobyada iyo Culeysyada Atamku uu sheego dhexda (interval) halkii uu ka sheegi lahaa hal tiro. Chlorine waxaa lagu taxay [35.446, 35.457], magnesium-na [24.304, 24.307]. Xisaabaha caadiga ah, isticmaal qiimayaasha keliga ah ee caadiga ah, 35.45 iyo 24.305, ilaa koorsadaadu si kale u sheegto mooyaane.