Nā nīnau hoʻohālike e kūkākūkā ana i nā pilina kemika
Ma kēia ʻatikala, e kūkākūkā mākou i nā pilina kemika—kekahi o nā manaʻo koʻikoʻi loa i ka kemika. ʻO nā pilina kemika nā pilina ma waena o nā ʻātoma e hiki ai iā lākou ke hana i nā hui a i ʻole nā mole. Aia kekahi mau ʻano maʻamau o nā pilina kemika: ionic, covalent, a me metallic. E ʻimi kākou i kēlā me kēia ʻano pilina ma o nā pilikia hoʻohālike a me nā kūkākūkā.
Hoʻopaʻa Ionic
Hana ʻia nā pilina ionic ke hoʻoili ʻia nā electrons mai kekahi ʻātoma a i kekahi, e hopena ana i nā ions i hoʻopiʻi maikaʻi ʻia (cations) a me nā ions i hoʻopiʻi maikaʻi ʻole ʻia (anions). A laila huki ʻia kēia mau cations a me nā anions kekahi i kekahi ma o nā mana electrostatic.
Laʻana Nīnau 1
Nīnau:
E hāʻawi i kahi laʻana a wehewehe pehea e hoʻokumu ʻia ai kahi pilina ionic ma waena o ka sodium (Na) a me ka chlorine (Cl).
Kūkākūkā:
He mea hui alkali ʻo Sodium (Na) me ka helu atomika 11, no laila ʻo kona hoʻonohonoho ʻana he 2, 8, 1. Loaʻa i ka Sodium ke nalowale hoʻokahi electron e hoʻokō ai i kahi hoʻonohonoho octet paʻa, e lilo ana i Na+.
He mea halogen ʻo Chlorine (Cl) me ka helu atomika 17, no laila ʻo kona hoʻonohonoho ʻana he 2, 8, 7. Loaʻa i ka Chlorine kekahi electron e hoʻokō i kahi hoʻonohonoho octet paʻa, e lilo ana i Cl-.
Ke hana ka sodium a me ka chlorine, nalowale ka sodium i hoʻokahi electron:
\[ \text{Na} \rightarrow \text{Na}^+ + \text{e}^- \]
ʻOiai ʻae ka chlorine i hoʻokahi electron:
\[ \text{Cl} + \text{e}^- \rightarrow \text{Cl}^- \]
ʻO ka hopena, ua huki ʻia nā ion Na+ a me Cl- kekahi i kekahi ma o nā mana electrostatic, e hana ana i ka hui sodium chloride (NaCl). ʻO ka hopena o ka hana he lattice kristal ikaika.
Nā Hoʻopaʻa Covalent
Hoʻokumu ʻia kahi pilina covalent ke kaʻana like nā ʻātoma ʻelua i hoʻokahi a ʻoi aku paha mau hui o nā electrons e hoʻokō i kahi hoʻonohonoho octet paʻa. Hiki i nā pilina covalent ke nonpolar (ua kaʻana like ʻia nā electrons) a i ʻole polar (ʻaʻole i kaʻana like ʻia nā electrons).
Laʻana Nīnau 2
Nīnau:
E hāʻawi a wehewehe pehea e hoʻokumu ʻia ai nā pilina covalent i loko o nā molekala wai (H2O).
Kūkākūkā:
Aia i loko o kahi molekole wai ʻelua mau ʻātoma hydrogen (H) a me hoʻokahi ʻātoma oxygen (O). ʻO 8 ka helu atomika o ka oxygen me ka hoʻonohonoho electron o 2, 6. Pono ka oxygen i ʻelua mau electrons hou aʻe e hoʻokō ai i kahi octet.
ʻO ka helu atomika ko ka hydrogen he 1 me ka hoʻonohonoho uila he 1. Pono ka hydrogen i hoʻokahi uila e hoʻokō i kahi hoʻonohonoho paʻa e like me ka helium.
I loko o kahi mole wai, kaʻana like kēlā me kēia ʻātoma hydrogen i hoʻokahi electron me ka oxygen. Kaʻana like ʻo Oxygen i ʻelua mau electrons (hoʻokahi me kēlā me kēia hydrogen), ʻoiai kaʻana like kēlā me kēia ʻātoma hydrogen i hoʻokahi electron me ka oxygen. ʻO ke ʻano Lewis o kahi mole wai:
\[ \kikokikona{O} \hema( \kikokikona{H} \ʻākau)_2 \]
Hoʻopuka kēia pilina i ʻelua mau pilina covalent polar no ka mea ʻoi aku ka electronegative o ka oxygen ma mua o ka hydrogen, no laila e huki ikaika ana i ka hui electron iā ia iho.
Nā Hoʻopaʻa Metala
Hana ʻia ka pilina metala ma waena o nā ʻātoma metala, kahi e hiki ai i nā electrons valence ke neʻe manuahi ma loko o ke ʻano metala, e hana ana i kahi 'kai o nā electrons'. Hāʻawi kēia hanana i nā metala i nā waiwai kūikawā, e like me ke alakaʻi uila a me ka wela kiʻekiʻe a me ka luster a me ka malleability.
Laʻana Nīnau 3
Nīnau:
E wehewehe pehea e hana ʻia ai nā pilina metala i ke keleawe (Cu).
Kūkākūkā:
He mea hoʻololi ke keleawe (Cu) me ka helu atomika 29 a me ka hoʻonohonoho electron [Ar] 3d10 4s1. I ka hoʻopaʻa ʻana i ka metala, launa pū nā electrons mai ka pūpū waho loa (nā electrons valence) me nā ʻātoma he nui, e hana ana i kahi 'kai o nā electrons' e hoʻopuni ana i ka nucleus maikaʻi o ka ion metala.
I loko o ke ʻano kristal o ka metala keleawe, hāʻawi kēlā me kēia ʻātoma Cu i kāna electron valence i ke kai o nā electrons. ʻAʻole i kaupalena ʻia ka pilina metala i kona mau hoalauna kokoke loa, akā huki pū i ka lattice metala holoʻokoʻa, e hopena ana i kona mau waiwai hiʻona.
Laʻana o nā Nīnau i Hoʻohui ʻia
E nānā kākou i kekahi mau laʻana o nā pilikia e pili ana i ka hui pū ʻana o nā ʻano pilina kemika like ʻole.
Laʻana Nīnau 4
Nīnau:
E hāʻawi a wehewehe i ke ʻano ionic a me covalent o nā hui magnesium oxide (MgO) a me carbon dioxide (CO2).
Kūkākūkā:
Makenesium Oxide (MgO)
He metala honua alkaline ka Magnesium (Mg) me ka helu atomika 12, hoʻonohonoho uila 2, 8, 2. Loaʻa iā Mg ka nalowale ʻana o ʻelua mau electrons e hoʻokō ai i kahi hoʻonohonoho kinoea hanohano paʻa, e lilo ana iā Mg2+.
ʻO ka oxygen (O) me ka helu atomika 8, ka hoʻonohonoho uila 2, 6, ke ʻae nei i ʻelua mau electrons e hoʻokō i kahi hoʻonohonoho kinoea hanohano paʻa, e lilo ana i O2-.
Ka hopena ionization:
\[ \kikokikona{Mg} \rightarrow \kikokikona{Mg}^{2+} + 2\ \kikokikona{e}^- \]
\[ \kikokikona{O} + 2\ \kikokikona{e}^- \rightarrow \kikokikona{O}^{2-} \]
ʻO ka hopena, ua huki ʻia nā ion Mg2+ a me O2- kekahi i kekahi ma o nā mana electrostatic, e hana ana i ka hui ionic magnesium oxide (MgO).
Kalapona Dioxide (CO2)
ʻO ke kalapona (C) me ka helu atomika 6, ka hoʻonohonoho uila 2, 4, pono i ʻehā mau uila e hoʻokō i kahi hoʻonohonoho octet.
ʻO ka oxygen (O) me ka helu atomika 8, ka hoʻonohonoho uila 2, 6, pono i ʻelua mau uila no kahi octet.
Pono ke kalapona e kaʻana like i ʻelua mau hui electrons me kēlā me kēia oxygen e hoʻokō ai i kahi octet:
\[ \kikokikona{O} = \kikokikona{C} = \kikokikona{O} \]
Hōʻike ka ʻōnaehana Lewis no CO2 i hoʻokahi pilina pālua ma waena o ke kalapona a me kēlā me kēia ʻātoma oxygen. He pilina covalent pālua kēia e hoʻopaʻa ai i ka molekole CO2. No ka mea, ʻoi aku ka electronegative o ka oxygen ma mua o ke kalapona, he pilina covalent polar nō hoʻi kēia.
Ka hopena
He mea nui ka hoʻopaʻa kemika no ke kūkulu ʻana a me ka hoʻomaopopo ʻana i nā ʻano molekala like ʻole a me nā hui kemika. Ma o nā laʻana a me nā kūkākūkā ʻana o nā pilina ionic, covalent, a me nā metala, ua ʻike mākou pehea e hana ʻia ai nā ʻano pilina like ʻole a pehea lākou e hoʻopilikia ai i nā ʻano kino o nā mea. He mea nui kēia ʻike no ka hoʻopili ʻana i nā manaʻo kemika i nā ʻano aʻo like ʻole, me ka biology, physics, a me nā ʻoihana loea ʻē aʻe. Lana ko mākou manaʻo ua kōkua kēia ʻatikala i ka hoʻonui ʻana i kou ʻike i ka hoʻopaʻa kemika!
