thumb|200px|right|Ethenium () In chemistry, ethenium, protonated ethylene or ethyl cation is a positive ion with the formula . It can be viewed as a molecule of ethylene () with one added proton (), or a molecule of ethane () minus one hydride ion (). It is a carbocation; more specifically, a nonclassical carbocation.
thumb|200px|right|Ethenium () In chemistry, ethenium, protonated ethylene or ethyl cation is a positive ion with the formula . It can be viewed as a molecule of ethylene () with one added proton (), or a molecule of ethane () minus one hydride ion (). It is a carbocation; more specifically, a nonclassical carbocation.
==Preparation== Ethenium has been observed in rarefied gases subjected to radiation. Another preparation method is to react certain proton donors such as trihydrogen cation|, helium hydride ion|, diazenylium|, and with ethane at ambient temperature and pressures below 1 mmHg. (Other donors such as methanium| and form ethanium preferably to ethenium.)
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).