Trichlorosilane
Thread Content
This post was last edited by Chemical Gas Purification on 2010-12-14 08:17. Everyone’s help is appreciated – what is the valence of silicon in trichlorosilane, +2 or +4? :L
Hehe, there are chemistry questions from junior and senior high school here; I really don’t know the answers. Please help answer them if you know them, fellow netizens.
It should be tetrapositive. Tetrachlorosilane is common.
It should be divalent, right? During the production of trichlorosilane, silicon powder reacts with hydrogen chloride to produce trichlorosilane and hydrogen, with silicon tetrachloride being another by-product. In this reaction process, silicon acts as a reducing agent. According to this, silicon in trichlorosilane has a positive valence of +2, while in silicon tetrachloride it has a positive valence of +4.
+2. Explain it using the shift of electrons; write out the structural formula. Between silicon and chlorine, the electrons on silicon shift towards chlorine, meaning silicon loses electrons. Three chlorines are equivalent to silicon losing 3 electrons. In the first step, silicon +3. Meanwhile, between silicon and hydrogen, the electrons on hydrogen shift towards silicon, meaning silicon gains electrons; one hydrogen allows silicon to gain one electron, resulting in a valence of -1 for silicon. 3 – 1 = 2
+2. Explain it using the shift of electrons; write out the structural formula. Between silicon and chlorine, the electrons on silicon shift towards chlorine, meaning silicon loses electrons. Three chlorines are equivalent to silicon losing 3 electrons. In the first step, silicon +3. Meanwhile, between silicon and hydrogen, the electrons on hydrogen shift towards silicon, meaning silicon gains electrons; one hydrogen allows silicon to gain one electron, resulting in a valence of -1 for silicon. 3 – 1 = 2
Let’s explain this using electronegativity. In the electronegativity scale, hydrogen has a value of 2.2, silicon 1.9, and chlorine 3.16. Therefore, in SiHCl3, the electronegativity of chlorine is greater than that of silicon; as a result, the electron pair leans toward chlorine, so chlorine carries a -1 charge. In the silicon-hydrogen bond, hydrogen’s electronegativity is slightly higher than that of silicon, so the electron pair leans toward hydrogen, giving hydrogen a -1 charge. Since the sum of the valences of all atoms in a molecule is zero, silicon’s valence is +4
Wow, can you still get points for so many wrong answers?
Thank you all for participating. I personally think it’s +4. Hey, can everyone give an accurate answer?