For example, carbon dioxide or CO2, list that there is 1 carbon (C) and 2 oxygens (O) present in the molecule. For methane, CH4, list carbon (C) and hydrogen (H). Methane comprises 1 atom of carbon and 4 atoms of hydrogen. For glucose, C6H12O6, list carbon (C), hydrogen (H), and oxygen (O). Glucose comprises 6 atoms of carbon, 12 atoms of hydrogen, and 6 atoms of oxygen.
For carbon dioxide (CO2), the relative atomic mass is 12. 011 amu for carbon and 15. 999 for oxygen. The atomic mass of an element is roughly equal to the summed mass of the protons and neutrons that it contains. Note that the relative atomic mass you find in the periodic table is scaled: it accounts for all of the isotopes of the element in the proportions that they naturally occur. [4] X Research source
In our carbon dioxide example, the mass of the single carbon atom is 12. 011 amu. Since there are 2 oxygen atoms, you would write 15. 999∗2=31. 998amu{\displaystyle 15. 999*2=31. 998amu}.
Round the answer as necessary, using significant digits. Remember to use the proper units. amu is the old abbreviation for atomic mass units, but the “most correct” modern unit is a lower-case u. [7] X Research source For carbon dioxide, the molecular weight can be found like so: 12. 011+31. 998=44. 009u{\displaystyle 12. 011+31. 998=44. 009u}.
1. 008∗4=4. 032u{\displaystyle 1. 0084=4. 032u}. 12. 011∗1=12. 011u{\displaystyle 12. 0111=12. 011u} 12. 011+4. 032=16. 043u{\displaystyle 12. 011+4. 032=16. 043u}
12. 011∗6=72. 066u{\displaystyle 12. 0116=72. 066u} 1,008∗12=12. 096u{\displaystyle 1,00812=12. 096u} 15. 999∗6=95. 994u{\displaystyle 15. 999*6=95. 994u} 72. 066+12. 096+95. 994=180. 156u{\displaystyle 72. 066+12. 096+95. 994=180. 156u}
