Mene ne hydrogen bond? The iri tasiri

Mene ne hydrogen bond? Duk aka sani misali na wannan connection ne talakawa ruwa (H2O). Saboda gaskiya cewa oxygen zarra (Ya) ne mafi electronegative fiye da biyu hydrogen zarra (H), shi jan kamar na hydrogen atoms hade electrons. Da kafa irin wannan covalent iyakacin duniya bond kafa dipole. Oxygen zarra yakan mallaki ba sosai manyan korau cajin da hydrogen atoms - a kananan tabbatacce cajin, wanda aka janyo hankalin zuwa electrons (da LonE biyu daga gare su) a kan oxygen zarra m H2O kwayoyin (Ina nufin, ruwa). Saboda haka, zamu iya cewa da hydrogen bond - a hanyar da karfi na janye tsakanin hydrogen zarra kuma wani electronegative zarra. An muhimmanci alama na hydrogen zarra ne cewa ta dauri da janye daga electrons da shi ya zama danda core (Ina nufin, proton, babu sauran electrons kare). Ko da yake hydrogen bond ne weaker fiye covalent, cewa shi sa a dukan jerin anomalous Properties na H2O (ruwa).

Mafi sau da yawa, wannan bond aka kafa tare da sunadaran da wadannan abubuwa: oxygen (Ya), nitrogen (N) da sunadarin flourine (F). Wannan na faruwa ga dalilin cewa sunadaran wadannan abubuwa ne a cikin kananan size, kuma suna da wani babban electronegativity. C kwayoyin halitta mafi girma size (S sulfur ko chlorine CL) Forms hydrogen bond ne weaker, duk da cewa ta su electronegativity wadannan abubuwa ne m to N (Ina nufin nitrogen).

Akwai iri biyu na hydrogen shaidu:

1. hydrogen intermolecular bond - ya auku tsakanin biyu kwayoyin, misali: methanol, ammonia, hydrogen fluoride.
2. intramolecular hydrogen bond - ya auku a cikin guda kwayoyin, kamar 2-nitrophenol.

Har ila yau, yanzu an yi imani da cewa hydrogen sinadaran bond rauni ne da kuma karfi. Sun bambanta daga juna a samar da makamashi da kuma bond tsawon (nesa tsakanin kwayoyin halitta):

1. hydrogen shaidu ne mai rauni. Energy - 10-30 KJ / mol, da bond tsawon - 30. Duk da abubuwa da aka jera a sama ne misalai na al'ada, ko raunana hydrogen bond.
2. hydrogen shaidu ne karfi. Energy - 400 KJ / mol, tsawon - 23-24. Data samu ta hanyar experimentation, nuna cewa da karfi shaidu aka kafa a cikin wadannan ions: wani ion-vodoroddiftorid [FHF] -, ion-hydrated hydroxide [HO-H-OH] -, ion oxonium hydrated [H2O-H-OH2] + kazalika da daban-daban da wasu kwayoyin da inorganic mahadi.

Tasiri na hydrogen-dake tsakanin

Anomalous dabi'u , daga ruwan maki kuma dab enthalpies na vaporization kuma da surface tashin hankali na wasu daga cikin mahadi za a iya dangana ga gaban hydrogen shaidu. Ruwa yana da anomalous dabi'u na duk wadannan kaddarorin, hydrogen fluoride da kuma ammonia - tafasasshen batu da kuma narkewa. Ruwa da kuma hydrogen fluoride a cikin m da ruwa jihohi saboda gaban a cikinsu na hydrogen intermolecular shaidu suna dauke da za a polymerized. Wannan dangantaka bayyana ba kawai ma high narkewa zafin jiki na wadannan kayan, amma kuma na low yawa. A cikinsa bisa dab hydrogen bond partially fadi, saboda abin da na ruwa da kwayoyin (H2O) suna cushe more densely.

A dimerization na wasu abubuwa (carboxylic acid, msl, benzoic da acetic acid) kuma za a iya bayyana ta a gaban hydrogen bonding. Dimer - biyu kwayoyin da cewa suna da nasaba da juna. Saboda wannan dalili, carboxylic acid ruwan batu fi da cewa da mahadi da ciwon kamar guda kwayoyin nauyi. Alal misali, acetic acid (CH3COOH) tafasar zafin jiki ne 391 K, yayin da acetone (CH3COCH3), shi ne 329 K.

Tasiri na hydrogen intramolecular shaidu

Wannan dangantaka kuma rinjayar da tsarin da kaddarorin daban-daban mahadi, kamar 2- kuma 4-nitrophenol. Amma ya fi shahara da muhimmanci misali na hydrogen bond - a deoxyribonucleic acid (gjrtw.: DNA). Wannan acid kwayoyin folded a cikin wani biyu Helix, biyu strands na wanda ake juna da hydrogen shaidu.