Izakhiwo Zamakhemikhali Zezinto Zomhlaba Ezine-Alkaline
Izinto zomhlaba ze-alkaline ziyiqembu lezinto ezisetafuleni le-periodic eziseqenjini le-IIA (iqembu lesi-2), okuyi-beryllium (Be), i-magnesium (Mg), i-calcium (Ca), i-strontium (Sr), i-barium (Ba), kanye ne-radium (Ra). Leli qembu libizwa ngokuthi "umhlaba we-alkaline" ngoba ama-oxide awo ayi-basic (alkaline) futhi ezinsukwini zokuqala ze-chemistry zazivame ukutholakala kumaminerali "omhlaba" (amatshe). Ngokombono wamakhemikhali, izinto zomhlaba ze-alkaline zaziwa ukuthi zinama-electron amabili e-valence ngakho-ke zivame ukwakha ama-ion ane-charge engu-+2. Lesi sici sibalulekile ekusebenzeni kabusha, izinhlobo zezibopho, kanye namaphethini okusabela ahlukile kulo mndeni wezinto.
1. Ukucushwa kwe-Electron kanye nezinombolo ze-Oxidation
Ngokuvamile, izakhi zomhlaba ze-alkaline zinesimo se-electron sangaphandle se-ns². Lokhu kusho ukuthi zinama-electron amabili e-valence egobolondweni lawo langaphandle. Njengoba zizinzile kakhulu lapho zifinyelela isimo segesi esihle, lezi zakhi zivame ukulahlekelwa ama-electron amabili lapho zisabela, zakha i-M²⁺ cation. Ngakho-ke, inombolo ye-oxidation evame kakhulu futhi ezinzile yezakhi zomhlaba ze-alkaline ingu-+2.
Ukuthambekela kokwakha ama-ion angu-+2 kwenza ama-compounds omhlaba ane-alkaline avame ukuba yi-ionic, ikakhulukazi ezintweni ezisindayo njenge-Ca, i-Sr, ne-Ba. Kodwa-ke, izinto ezincane ezifana ne-Be zinezakhiwo ezihlukile kancane; ama-compounds azo avame ukuba ne-covalent kakhulu ngenxa yokuvuleka kwawo okuphezulu.
2. Amandla e-Ionization kanye ne-Reactivity
Ukusabela kwezinto zomhlaba ze-alkaline kuyanda kusukela phezulu kuya phansi kweqembu. Lokhu kuhlobene nokwanda kwe-athomu radius kanye nokwehla kwamandla e-ionization. Njengoba wehla, ama-electron e-valence aqhelelene ne-nucleus futhi asuswa kalula, ngakho-ke i-element iba nomthelela omkhulu.
Uhlelo olujwayelekile lokuthambekela kokusabela yilolu:
Yiba < Mg < Ca < Sr < Ba < Ra
Kodwa-ke, kufanele kuqashelwe ukuthi i-beryllium ihlukile futhi ayisebenzi kahle kakhulu kunezinye izitho. Ayisebenzi ngisho namanzi ngaphansi kwezimo ezijwayelekile ngoba ungqimba oluncane lwe-oxide lwakha ungqimba lwe-oxide oluvikela ubuso bayo. 3. Ukusabela Namanzi Enye yezimpawu zamakhemikhali ezivelele zezinsimbi zomhlaba ze-alkaline yikhono lazo lokusabela namanzi, yize kungenjalo ngokushesha njengezinsimbi ze-alkali (iqembu 1). - I-Be: cishe ayisebenzi namanzi ngenxa yongqimba lwe-BeO oluzinzile. - I-Mg: isabela kancane kakhulu namanzi abandayo, kodwa isabela ngokushesha kakhulu namanzi ashisayo noma umusi. - I-Ca, Sr, i-Ba: isabela namanzi abandayo ukukhiqiza ama-hydroxide negesi ye-hydrogen. Izibonelo zokusabela: - Nge-calcium: I-Ca(s) + 2H₂O(l) → I-Ca(OH)₂(aq) + I-H₂(g) - Nge-magnesium enomusi: I-Mg(s) + I-H₂O(g) → I-MgO(s) + I-H₂(g) Lokhu kusabela kubonisa ukuthi izinsimbi zomhlaba ze-alkaline ziyizinto ezinciphisa amandla kakhulu, ngoba zinganciphisa amanzi abe yigesi ye-hydrogen. 4. Ukusabela Ngokuphathelene Nokwakheka Kwe-Oksijini Ne-Oxide Izakhi zomhlaba ze-alkaline zivame ukusabela nomoya-mpilo ukuze zakhe ama-oxide. Umkhiqizo oyinhloko ngokuvamile i-oxide elula (MO). Kodwa-ke, izakhi ezisindayo zingakha nama-peroxide. - Mg + O₂ → MgO - 2Ca + O₂ → 2CaO (eyinhloko) - I-Ba ivame ukwakha i-BaO₂ (i-peroxide) ngaphansi kwezimo ezithile: I-Ba + O₂ → I-BaO₂ Ukuqina kwama-oxide kuyanda kusukela phezulu kuya phansi. I-BeO iyi-amphoteric (ingaba yi-acidic futhi iyisisekelo), i-MgO iyisisekelo esibuthakathaka, kuyilapho i-CaO, i-SrO, ne-BaO ziyisisekelo kakhulu futhi zisabela ngamanzi ukuze zakhe ama-hydroxide. 5. Ukwakheka Kwe-Hydroxide kanye Nesisekelo Ama-hydroxide omhlaba we-alkaline anefomula ejwayelekile i-M(OH)₂. Amandla ayisisekelo kanye nokuncibilika kwama-hydroxide kuyanda kusukela phezulu kuya phansi kweqembu: - I-Be(OH)₂: i-amphoteric, ayincibiliki kahle. - I-Mg(OH)₂: isisekelo esibuthakathaka, ukuncibilika okuphansi (okwaziwa ngokuthi “ubisi lwe-magnesia” lwemithi yokunciphisa i-acid). - I-Ca(OH)₂: iyancibilika kancane, eyaziwa ngokuthi i-slaked lime. - I-Sr(OH)₂ kanye ne-Ba(OH)₂: izisekelo ezincibilika kakhulu neziqinile. Lokhu kwanda kokuncibilika kuthonywa ukwehla kwamandla e-lattice kanye noshintsho kumandla okunciphisa i-hydration. Sekukonke, kuma-hydroxide eqembu lesi-2, ukuncibilika kwehla ngenxa yokuthi amandla e-lattice ancipha kakhulu kunokwehla kwamandla okunciphisa i-hydration. 6. Ukusabela ngama-Halogens kanye ne-Halide Ukwakheka Izinsimbi zomhlaba ze-alkaline zisabela nama-halogens (F₂, Cl₂, Br₂, I₂) ukuze zakhe ama-ionic halides ngefomula i-MX₂. Izibonelo: - Mg + Cl₂ → MgCl₂ - Ca + Br₂ → CaBr₂ Ama-halide omhlaba we-alkaline ngokuvamile angama-ionic futhi anamaphuzu aphezulu okuncibilika. Kodwa-ke, kunezimo ezibalulekile: I-BeCl₂ i-covalent kakhulu futhi ingakha izakhiwo ze-polymeric. Ngaphezu kwalokho, ukuncibilika kwama-halide kuyahlukahluka; isibonelo, i-CaF₂ ayincibiliki kahle ngenxa yamandla ayo aphezulu kakhulu e-lattice. 7. Ukusabela Ngama-Acids Nezakhiwo Njengezinto Ezinciphisa Ama-halide omhlaba we-alkaline ngokuvamile asabela nama-asidi ukukhiqiza usawoti kanye negesi ye-hydrogen, okubonisa indima yawo njengezinto ezinciphisa. Izibonelo: - Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g) - Ca(s) + H₂SO₄(aq) → CaSO₄(s) + H₂(g) Ukusabela kwe-calcium nge-sulfuric acid kungancishiswa ngenxa yokwakheka kwengqimba ye-CaSO₄ engancibiliki kahle. Ngokuvamile, uma iqembu liphansi, kulapho ukusabela ngama-acid kushesha khona ngoba insimbi i-oxidized kalula. 8. Ukwakheka Kwe-Carbonate, Sulfate, kanye Nosawoti We-Nitrate Usawoti womhlaba we-alkaline unephethini yokuncibilika ephawulekayo: a) I-Carbonate (MCO₃) Ama-carbonate omhlaba we-alkaline ngokuvamile kunzima ukuwancibilikisa emanzini, ikakhulukazi i-CaCO₃, i-SrCO₃, kanye ne-BaCO₃. I-MgCO₃ nayo kunzima ukuyincibilikisa. I-CaCO₃ ivame kakhulu njenge-limestone, imabula, kanye ne-calcite. Lawa ma-carbonate ayabola uma eshiswa: - CaCO₃(s) → CaO(s) + CO₂(g) b) I-Sulfate (MSO₄) Ukuncibilika kwama-sulfate kwehla kusuka phezulu kuya phansi: - I-MgSO₄ iyancibilika kahle, - I-CaSO₄ iyancibilika kancane, - I-BaSO₄ ayincibiliki kahle (ivame ukusetshenziswa ezinqubweni ze-x-ray njengendlela yokuhlukanisa ngoba iphephile futhi ayincibiliki). c) I-Nitrate (M(NO₃)₂) Ama-nitrate omhlaba we-alkaline ngokuvamile ancibilika emanzini. Uma eshiswa, lawa ma-nitrate avame ukubola abe ama-oxide, i-nitrogen dioxide, kanye nomoya-mpilo: - 2Ca(NO₃)₂ → 2CaO + 4NO₂ + O₂ 9. Izakhiwo Eziyinkimbinkimbi Nezakhamzimba ze-Amphoteric ze-Beryllium I-Beryllium iyilungu elihlukile kakhulu. Ngenxa yobukhulu bayo obuncane kanye nokushaja okuphezulu kwe-+2, i-Be²⁺ inamandla amakhulu okuhlukanisa ngakho ama-compound ayo aqinile kakhulu. I-Be(OH)₂ kanye ne-BeO ziyi-amphoteric, ziyakwazi ukusabela ngama-acid kanye nezisekelo: - Ngama-acid: I-Be(OH)₂ + 2HCl → I-BeCl₂ + 2H₂O - Inezisekelo eziqinile (ezakha ama-complex e-beryllate): I-Be(OH)₂ + 2OH⁻ → [Be(OH)₄]²⁻ Lezi zakhiwo eziyinkimbinkimbi zibonisa ukuthi i-chemistry ye-beryllium ifana kakhulu neyezinye izinto ezingezona ezensimbi kunezinye izinsimbi zomhlaba ze-alkaline. 10. Isiphetho Izakhiwo zamakhemikhali zezinto zomhlaba ze-alkaline zithonywa kakhulu ukwakheka kwazo kwe-ns² electron okuzenza ziqine ngesimo sama-ion e-M²⁺. Ukusabela kabusha kuyanda kusuka ku-Be kuya ku-Ba njengoba amandla e-ionization ehla. Zisabela ngamanzi, ama-acid, ama-halogen, kanye nomoya-mpilo ngendlela ethile: ukwakha ama-oxide, ama-hydroxide, kanye nosawoti we-ionic. Ngaphezu kwalokho, izinguquko ekuncibilikeni kwamakhemikhali anjenge-hydroxide, ama-carbonate, nama-sulfate zibonisa izitayela ezibalulekile zesikhathi ekuhlaziyweni kwamakhemikhali. Phakathi kwazo, i-beryllium ihlukile ngezakhiwo zayo ze-amphoteric kanye nokuthambekela okuqinile kwe-covalent. Ukuqonda izakhiwo zamakhemikhali zezinsimbi zomhlaba ze-alkaline kubalulekile hhayi nje kuphela kumbono wezikhathi ezithile kodwa futhi nasekusetshenzisweni kwezimboni, ezemvelo, kanye nokwansuku zonke—isibonelo, ku-lime (CaO/Ca(OH)₂), amaminerali e-carbonate, ama-antacid e-Mg(OH)₂, ngisho ne-BaSO₄ kwezokwelapha.
