Dinitrogen tetroxide is a binary, molecular compound. QUESTION: Which of the following is the correct formula for dinitrogen tetroxide? A. NO, B. N2O3, C. N2O4, D. NO2 Dinitrogen tetroxide is a binary, molecular compound. Binary: two elements (N and O) Molecular: both elements are nonmetals Rule: name first element, then second element, but… Change ending of second element to ide Add Greek prefix corresponding to subscript: di=2, tri=3, tetra=4, penta=5, hexa=6, hepta=7 octa=8, nona=9, deca=10 SCRIPT: Which of the following is the correct formula for dinitrogen tetroxide? A. NO, B. N2O3, C. N2O4, D. NO2 PAUSE To write the formula of a compound given its name we need to first classify the compound, then apply the rule for that type of compound. CLICK Dinitrogen tetroxide is a binary, molecular compound. By binary, we mean that it is made up of only two elements…. In this case, nitrogen and oxygen HIGHLIGHT nitrogen and ox in dinitrogen tetroxide CLICK It’s a molecular compound because both elements are nonmetals. If the first element were a metal, the compound would be classified as ionic. The rule for naming binary molecular molecular compound is this. Name the first element, then second element, but… Change ending of second element to ide… And… We must add Greek prefix to each element’s name. The prefix should correspond to the subscript. The prefix di corresponds to a subscript of 2… Therefore, the subscript for nitrogen in this compound is 2. Therefore, choices A and D are wrong. CROSS OUT choices A and D. The prefix tetra corresponds to a subscript of 4. Therefore, the subscript for oxygen in this compound is 4. It is customary to drop the a in tetra when followed by the letter o. So, instead of tetra-oxide, we simply say tetroxide. Other greek prefixes you should memorize are Tri for 3, Penta for 5, Hexa for 6, hepta for 7, octa for 8, nona for 9, and deca for 10. CLICK PAUSE END RECORDING

Video ID: 1-26-3 © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Narrator: Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08