Kauj Ruam 1: Txiav txim siab hom qauv, pib nrog cov pa roj carbon atoms.
Rau homologues nrog cov qauv zoo sib xws, ntau cov pa roj carbon atoms, qhov siab dua qhov melting point.Piv txwv li, ethane (2 carbons) muaj qhov melting point ntawm kwv yees li -183.3 degree, thaum pentane (5 carbons) muaj qhov melting point ntawm kwv yees li -129.7 degree, qhia meej txog qhov sib txawv. Yog tias lawv yog isomers, mus rau kauj ruam tom ntej.
Kauj ruam 2: Rau isomers, xav txog tus naj npawb ntawm ceg thiab symmetry.
Yog hais tias tus naj npawb ntawm carbon atoms yog tib yam (isomers):
Txoj cai tseem ceeb: Cov ceg ntau dua, qhov phem dua qhov molecular symmetry, thiab qhov qis melting point. Piv txwv li, n-pentane (unbranched) muaj qhov melting point ntawm -129.7 degree, thaum isopentane (1 ceg) muaj qhov melting point ntawm -159.9 degree, zoo kawg nkaus ua raws li txoj cai no.
Lus Cim Tshwj Xeeb: Qhov zoo dua qhov molecular symmetry, qhov siab dua qhov melting point. Piv txwv li, neopentane (ib tug heev symmetrical plaub-branched qauv) muaj ib tug siab melting point tshaj n-pentane, ncav cuag -16.6℃.
Kauj ruam 3: Xa mus rau cov cai tshwj xeeb rau alkanes.
Nyob rau hauv ncaj- saw alkanes, molecules nrog ib tug txawm tus naj npawb ntawm carbon atoms muaj symmetry zoo dua thiab ib tug ntau dua nyob rau hauv melting point tshaj cov uas muaj ib tug khib tus naj npawb ntawm carbon atoms, tsim ob qho tib si melting point nkhaus, uas yuav pab tau zoo - kho qhov kev twv txiaj. Rau alkenes thiab alkynes, txoj cai no tsis pom tseeb, thiab thawj ob kauj ruam tuaj yeem ua raws ncaj qha.