Ngā Tauira Pātai e Matapaki ana i ngā Here Ā-Ioni
Ko te here ionic he momo here matū e hangaia ana e te whakawhiti i tētahi, neke atu rānei o ngā irahiko mai i tētahi ngota ki tētahi atu, ka hua ake he ion e rua me ngā utu rerekē ka kukume tetahi ki tetahi. Ko tēnei here ka puta i waenga i ngā konganuku me ngā mea ehara i te konganuku. I roto i tēnei tuhinga, ka tirohia e tātou ngā tauira me ngā kōrero e pā ana ki te here ionic hei āwhina i a tātou ki te mārama ake ki tēnei ariā.
Te Whakamāramatanga me ngā Āhuatanga o ngā Here Ā-Ionika
Ka puta ngā hononga katote ina taunekeneke ngā ngota hei whakatutuki i tētahi whirihoranga irahiko pumau ake. I te nuinga o te wā, ka ngaro ngā irahiko i ngā ngota konganuku hei whakatutuki i tētahi whirihoranga hau rangatira, ka noho hei kationa utu pai. I tetahi atu taha, ka whiwhi ngā ngota kore-konganuku i ngā irahiko hei huri hei anion utu kino. Ko tētahi tauira noa o te hononga katote ko te hanganga o te konutai pūhaumāota (NaCl) mai i te konutai (Na) me te mārore (Cl).
Ko te whirihoranga irahiko o te konutai (Na) he 2,8,1, ā, ka ngaro pea tētahi irahiko hei whakatutuki i tētahi whirihoranga pumau o te 2,8. I tētahi atu taha, ko te whirihoranga irahiko o te chlorine (Cl) he 2,8,7, ā, ka tango pea i tētahi irahiko hei whakatutuki i tētahi whirihoranga pumau o te 2,8,8. Ina ngaro tētahi irahiko o te konutai ki te chlorine, ka hangaia ngā iona Na⁺ me Cl⁻ e kukume ana tetahi ki tetahi hei hanga i tētahi hononga ionic, ka puta te tote NaCl.
Tauira Raru 1: Te Hanganga o ngā Here Ionic i roto i te NaCl
1. Pātai: Whakamāramahia te hanganga o ngā hononga irahiko i waenga i te konutai (Na) me te haurore (Cl).
Ngā Whakautu me te Kōrero:
– Hipanga 1: Whakatauhia te whirihoranga irahiko.
– Konutai (Na): Tau ātomo 11, whirihoranga irahiko 2,8,1.
– Haumāota (Cl): Tau ātomo 17, whirihoranga irahiko 2,8,7.
– Hipanga 2: Whakatauhia ngā iahiko ngota.
– Ka tukuna e te konutai (Na) tētahi irahiko hei whakatutuki i te whirihoranga 2,8, ka noho ko te iona Na⁺.
– Ka tangohia e te hauota (Cl) tētahi irahiko hei whakatutuki i te whirihoranga 2,8,8, ka noho ko te iona Cl⁻.
– Hipanga 3: Te hanga hononga.
– Ka tukuna e te konutai ngā irahiko hei Na⁺ me te utu o te +1.
– Ka tangohia e te haumāota ngā irahiko hei Cl⁻ me te utu o te -1.
– Ka kukume ngā iona Na⁺ me Cl⁻ tetahi ki tetahi, ka hanga hononga iona i roto i te pūhui NaCl pumau.
Tauira Pātai 2: Te Hanganga o ngā Here Ionic i roto i te MgO
2. Pātai: Whakamāramahia te hanganga o te hononga irahiko i waenga i te konupūmā (Mg) me te hāora (O) hei hanga i te waikura konupūmā (MgO).
Ngā Whakautu me te Kōrero:
– Hipanga 1: Whakatauhia te whirihoranga irahiko.
– Konupora (Mg): Tau ātomo 12, whirihoranga irahiko 2,8,2.
– Hāora (O): Tau ātomo 8, whirihoranga irahiko 2,6.
– Hipanga 2: Whakatauhia ngā iahiko ngota.
– Ka tukuna e te konupūmā (Mg) ngā irahiko e rua hei whakatutuki i te whirihoranga 2,8, ka noho ko te katote Mg²⁺.
– Ka tangohia e te hāora (O) ngā irahiko e rua hei whakatutuki i te whirihoranga 2,8, ka noho ko te katote O²⁻.
– Hipanga 3: Te hanga hononga.
– Ka tukuna e te konupūmā ngā irahiko e rua hei Mg²⁺ me te utu o te +2.
– Ka tangohia e te hāora ngā irahiko e rua hei O²⁻ me te utu o te -2.
– Ka kukume ngā katote Mg²⁺ me O²⁻ tetahi ki tetahi hei hanga hononga katote i roto i te pūhui MgO.
Tauira 3: Te Tātai i te Pūngao o tētahi Whakaharatau Whakakotahi NaCl
3. Pātai: Whakatauhia te pūngao whatunga e hiahiatia ana hei hanga i te NaCl mai i ōna katote.
Ngā Whakautu me te Kōrero:
Ko te pūngao whatanga ko te pūngao e tukuna ana ina honoa ngā katote i roto i te āhua hau hei hanga i te kotahi ira o te tioata totoka o te pūhui katote. Ka taea te whakatau tata i te pūngao whatanga o te NaCl mā te whakamahi i te whārite Born-Haber.
Ka taea te whakaatu i te pūngao whatanga hei te rerekētanga pūngao katoa i waenga i ngā katote i te āhua hau me te pūngao ina herea ki roto i te whatanga karaihe totoka.
Mō te NaCl:
– Pūngao whakapūmau Na: ΔH_sub = 107 kJ/mol
– Pūngao whakapūngao Na: ΔH_ion = 496 kJ/mol
– Pūngao wehenga o Cl₂: ΔH_diss/2 = 122 kJ/mol
– Te hononga irahiko o Cl: ΔH_ea = -349 kJ/mol
– Pūngao whatanga (U): Kāore i te mōhiotia, me kimi e tātou.
Mai i te huringa Born-Haber, ka taea e tātou te tuhi:
U = ΔH_sub(Na) + ΔH_ion(Na) + ΔH_diss(Cl₂)/2 + ΔH_ea(Cl) – ΔH_form
Ki te mōhio tātou ko te enthalpy o te hanganga (ΔH_form) o NaCl he -411 kJ/mol, kāti:
U = (107 + 496 + 122 – 349) kJ/mol – (-411 kJ/mol)
U = 107 + 496 + 122 – 349 + 411
U ≈ 787 kJ/mol
Tauira 4: Kauwhata o te Pūngao Pūmanawa me te Tawhiti i waenganui i ngā Iona
4. Pātai: Tuhia he kauwhata o te pūngao pūmanawa ki te tawhiti i waenga i ngā iona Na⁺ me Cl⁻ i roto i te NaCl, ā, whakamāramahia te mea ka puta ina rerekē te tawhiti i waenga i ngā iona e rua.
Ngā Whakautu me te Kōrero:
Ka taea te whakaahua i te pūngao pūmanawa i waenga i ngā katote e rua i roto i tētahi pūhui katote mā te whakamahi i te whārite a Coulomb:
\[ E \propto \frac{q_1 q_2}{r} \]
Ko \( E \) te pūngao pūmanawa, ko \( q_1 \) me \( q_2 \) ngā utu katote, ā, ko \( r \) te tawhiti i waenga i ngā katote. Ko te kauwhata o te pūngao pūmanawa me te tawhiti i waenga i ngā katote he kōpiko e heke ana i te whakatata atu ki te kore, kātahi ka piki tere i te whakatata atu ki te kore.
– Tawhiti Nui (he tino nui te r): E tata ana te pūngao pūmanawa ki te kore nā te mea he ngoikore rawa te kaha kukume i waenga i ngā iona Na⁺ me Cl⁻.
– Te Tawhiti Pai (tata ki te tawhiti whatunga tioata): Ka tae te pūngao pūmanawa ki tōna uara iti rawa, e tohu ana i te āhua tino pumau e kukumehia ana te Na⁺ me te Cl⁻ engari kāore i te tino tata. Koinei te tawhiti e tino pumau ai te tioata NaCl.
– Tawhiti Iti (he tino iti te r): Ka piki tere te pūngao pūmanawa nā te mea he ātete i waenga i ngā kapua irahiko o ngā iona e rua, ka peia atu ai rātou tetahi i tetahi.
Hei whakamutunga, ko te hononga ionic he kaupapa matua i roto i te matū, e uru ana ki te taunekeneke hikohiko i waenga i ngā ion e rerekē ana te utu. Mā te mārama ki tēnei ariā mā roto i ngā momo raruraru me ā rātou otinga ka āwhina i a tātou ki te mārama ki te whanonga o ngā pūhui i raro i ngā āhuatanga rerekē. Mā te mōhio ki tēnei ariā, ka taea e tātou te mārama ki te hanganga o ngā hononga matū me te hanganga o ngā hanganga tioata e tūtaki ana tātou i ia rā.
