Cov Khoom Siv Tshuaj Lom Zem ntawm Cov Khoom Alkaline Earth
Cov ntsiab lus ntawm lub ntiaj teb alkaline yog ib pawg ntawm cov ntsiab lus hauv lub rooj teev sijhawm uas nyob hauv pawg IIA (pawg 2), uas yog beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), thiab radium (Ra). Pawg no hu ua "alkaline earth" vim tias lawv cov oxides yog cov yooj yim (alkaline) thiab thaum ntxov ntawm chemistry feem ntau pom muaj nyob rau hauv "lub ntiaj teb" cov zaub mov (pob zeb). Los ntawm kev xav txog tshuaj lom neeg, cov ntsiab lus ntawm lub ntiaj teb alkaline paub tias muaj ob lub electrons valence yog li lawv feem ntau tsim cov ions nrog tus nqi ntawm +2. Cov khoom no yog qhov tseem ceeb rau kev ua haujlwm, hom kev sib txuas, thiab cov qauv tshuaj tiv thaiv hauv tsev neeg ntawm cov ntsiab lus no.
1. Kev Teeb tsa Electron thiab Cov Naj Npawb Oxidation
Feem ntau, cov khoom siv alkaline earth muaj cov qauv hluav taws xob sab nraud ntawm ns². Qhov no txhais tau tias lawv muaj ob lub electrons valence hauv lawv lub plhaub sab nraud tshaj plaws. Txij li thaum lawv ruaj khov dua thaum lawv ua tiav cov qauv roj zoo, cov khoom no feem ntau poob ob lub electrons thaum lawv teb, tsim cov M²⁺ cation. Yog li ntawd, tus lej oxidation feem ntau thiab ruaj khov rau cov khoom siv alkaline earth yog +2.
Qhov kev nyiam tsim cov ions +2 ua rau cov tshuaj alkaline earth feem ntau yog ionic, tshwj xeeb tshaj yog rau cov khoom hnyav dua xws li Ca, Sr, thiab Ba. Txawm li cas los xij, cov khoom me me xws li Be muaj cov yam ntxwv sib txawv me ntsis; lawv cov tshuaj feem ntau yog covalent ntau dua vim lawv cov polarizability siab.
2. Lub Zog Ionization thiab Reactivity
Qhov ua haujlwm ntawm cov khoom siv alkaline earth nce ntxiv los ntawm sab saud mus rau hauv qab ntawm pawg. Qhov no muaj feem cuam tshuam nrog kev nce ntawm atomic radius thiab txo qis ionization zog. Thaum koj nqes mus, cov valence electrons nyob deb ntawm lub nucleus thiab yooj yim tshem tawm, yog li cov khoom ua haujlwm ntau dua.
Cov kev txiav txim dav dav ntawm cov qauv reactivity yog:
Ua < Mg < Ca < Sr < Ba < Ra
Txawm li cas los xij, nws yuav tsum tau sau tseg tias beryllium yog qhov tshwj xeeb thiab tsis tshua muaj zog dua li lwm cov tswv cuab. Nws tsis txawm tias ua rau dej sai sai hauv qab cov xwm txheej ib txwm muaj vim tias ib txheej oxide nyias nyias tsim uas tiv thaiv nws qhov chaw. 3. Kev Ua Rau Dej Ib qho ntawm cov khoom siv tshuaj lom neeg zoo tshaj plaws ntawm cov hlau alkaline earth yog lawv lub peev xwm los ua rau dej, txawm hais tias tsis sai npaum li cov hlau alkali (pawg 1). - Be: yuav luag tsis ua rau dej vim yog txheej BeO ruaj khov. - Mg: ua rau dej txias qeeb heev, tab sis ua rau dej kub lossis pa dej sai dua. - Ca, Sr, Ba: ua rau dej txias los tsim cov hydroxides thiab hydrogen gas. Piv txwv ntawm kev ua rau: - Rau calcium: Ca(s) + 2H₂O(l) → Ca(OH)₂(aq) + H₂(g) - Rau magnesium nrog pa dej: Mg(s) + H₂O(g) → MgO(s) + H₂(g) Cov kev ua rau no qhia tau tias cov hlau alkaline earth yog cov neeg sawv cev txo qis muaj zog heev, vim tias lawv tuaj yeem txo dej rau hydrogen gas. 4. Cov tshuaj tiv thaiv nrog Oxygen thiab Oxide Tsim Cov khoom siv hauv av alkaline feem ntau cuam tshuam nrog oxygen los tsim cov oxides. Cov khoom tseem ceeb feem ntau yog cov oxide yooj yim (MO). Txawm li cas los xij, cov khoom hnyav dua kuj tuaj yeem tsim cov peroxides. - Mg + O₂ → MgO - 2Ca + O₂ → 2CaO (thawj) - Ba feem ntau tsim BaO₂ (peroxide) nyob rau hauv qee qhov xwm txheej: Ba + O₂ → BaO₂ Lub hauv paus ntawm oxides nce ntxiv los ntawm sab saud mus rau hauv qab. BeO yog amphoteric (tuaj yeem yog ob qho tib si acidic thiab basic), MgO yog weakly basic, thaum CaO, SrO, thiab BaO yog basic muaj zog thiab cuam tshuam nrog dej los tsim cov hydroxides. 5. Hydroxide Tsim thiab Basicity Alkaline earth hydroxides muaj cov mis dav dav M (OH)₂. Lub zog yooj yim thiab solubility ntawm hydroxides nce ntxiv los ntawm sab saud mus rau hauv qab ntawm pawg: - Be(OH)₂: amphoteric, yaj tsis zoo. - Mg(OH)₂: lub hauv paus tsis muaj zog, yaj tsis zoo (hu ua "mis nyuj ntawm magnesia" rau antacids). - Ca(OH)₂: yaj me ntsis, hu ua slaked lime. - Sr(OH)₂ thiab Ba(OH)₂: yaj ntau dua thiab muaj zog dua. Qhov kev nce ntxiv ntawm kev yaj no yog cuam tshuam los ntawm kev txo qis ntawm lub zog lattice thiab kev hloov pauv ntawm lub zog hydration. Zuag qhia tag nrho, rau pawg 2 hydroxides, kev yaj nce qis vim tias lub zog lattice txo qis ntau dua li qhov txo qis ntawm lub zog hydration. 6. Kev cuam tshuam nrog Halogens thiab Halide Tsim Alkaline av hlau react nrog halogens (F₂, Cl₂, Br₂, I₂) los tsim cov ionic halides nrog cov mis MX₂. Piv txwv li: - Mg + Cl₂ → MgCl₂ - Ca + Br₂ → CaBr₂ Cov tshuaj halides hauv av alkaline feem ntau yog ionic thiab muaj cov ntsiab lus melting siab. Txawm li cas los xij, muaj qee qhov kev zam tseem ceeb: BeCl₂ yog covalent ntau dua thiab tuaj yeem tsim cov qauv polymeric. Tsis tas li ntawd, qhov solubility ntawm halides sib txawv; piv txwv li, CaF₂ tsis yaj zoo vim nws lub zog lattice siab heev. 7. Cov tshuaj tiv thaiv nrog Acids thiab Properties ua cov neeg sawv cev txo qis Alkaline earth halides feem ntau cuam tshuam nrog cov kua qaub los tsim cov ntsev thiab hydrogen roj, qhia lawv lub luag haujlwm ua cov neeg sawv cev txo qis. Piv txwv li: - Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g) - Ca(s) + H₂SO₄(aq) → CaSO₄(s) + H₂(g) Cov tshuaj tiv thaiv ntawm calcium nrog sulfuric acid tuaj yeem qeeb qeeb vim yog kev tsim cov txheej ntawm CaSO₄ uas tsis yaj zoo. Feem ntau, qhov tsawg dua pawg, qhov sai dua qhov kev cuam tshuam nrog cov kua qaub vim tias cov hlau yooj yim oxidized. 8. Kev tsim cov Carbonate, Sulfate, thiab Nitrate Salts Cov ntsev av alkaline muaj tus qauv solubility: a) Carbonate (MCO₃) Cov av alkaline carbonates feem ntau nyuaj rau yaj hauv dej, tshwj xeeb tshaj yog CaCO₃, SrCO₃, thiab BaCO₃. MgCO₃ kuj nyuaj rau yaj. CaCO₃ yog ib qho tshwm sim ntau heev li limestone, marble, thiab calcite. Cov carbonates no lwj thaum cua sov: - CaCO₃(s) → CaO(s) + CO₂(g) b) Sulfate (MSO₄) Qhov yaj ntawm sulfates txo qis los ntawm sab saud mus rau hauv qab: - MgSO₄ yaj tau zoo, - CaSO₄ yaj tau me ntsis, - BaSO₄ yaj tsis zoo heev (feem ntau siv rau hauv cov txheej txheem x-ray ua cov khoom sib piv vim nws muaj kev nyab xeeb thiab tsis yaj). c) Nitrate (M(NO₃)₂) Cov nitrates av alkaline feem ntau yaj tau hauv dej. Thaum cua sov, cov nitrates no feem ntau lwj mus rau hauv oxides, nitrogen dioxide, thiab oxygen: - 2Ca(NO₃)₂ → 2CaO + 4NO₂ + O₂ 9. Cov khoom sib xyaw thiab cov khoom amphoteric ntawm Beryllium Beryllium yog tus tswv cuab deviant tshaj plaws. Vim nws qhov me me thiab siab +2 them, Be²⁺ muaj lub zog polarizing loj yog li nws cov tshuaj sib xyaw ua ke ntau dua. Be(OH)₂ thiab BeO yog amphoteric, muaj peev xwm ua rau ob qho tib si acids thiab bases: - Nrog acids: Be(OH)₂ + 2HCl → BeCl₂ + 2H₂O - Nrog cov bases muaj zog (tsim cov beryllate complexes): Be(OH)₂ + 2OH⁻ → [Be(OH)₄]²⁻ Cov khoom sib xyaw no qhia tau tias beryllium cov chemistry zoo ib yam li qee cov nonmetals dua li lwm cov alkaline earth hlau. 10. Xaus Lus Cov khoom siv tshuaj lom neeg ntawm alkaline earth elements raug cuam tshuam los ntawm lawv cov ns² electron configuration uas ua rau lawv ruaj khov hauv daim ntawv ntawm M²⁺ ions. Reactivity nce ntxiv los ntawm Be mus rau Ba thaum lub zog ionization txo qis. Lawv ua rau dej, acids, halogens, thiab oxygen hauv tus qauv yam ntxwv: tsim cov oxides, hydroxides, thiab ionic ntsev. Tsis tas li ntawd, cov kev hloov pauv hauv solubility ntawm cov tshuaj xws li hydroxides, carbonates, thiab sulfates qhia txog cov qauv tseem ceeb hauv kev tshuaj xyuas tshuaj. Ntawm lawv, beryllium yog qhov tshwj xeeb hauv nws cov khoom amphoteric thiab cov kev sib raug zoo ntawm covalent. Kev nkag siab txog cov khoom siv tshuaj lom neeg ntawm cov hlau alkaline earth yog qhov tseem ceeb tsis yog hauv kev tshawb fawb txog lub sijhawm xwb tab sis kuj tseem siv rau hauv kev lag luam, ib puag ncig, thiab kev siv txhua hnub - piv txwv li, hauv cov kua qaub (CaO / Ca (OH) ₂), cov zaub mov carbonate, Mg (OH) ₂ antacids, thiab txawm tias BaSO ₄ hauv tshuaj.
