thanks 4 replying to my question about atomic mass... now i understood that why do we call it relative mass, but i still have a query(which i had asked in same question but 4 some reason it wasn't replied). So, my question is, if i want to find atomic mass of say NITROGEN, why should i compare it carbon-12, or as mention in video by mona maam y should i compare it with hydrogen and say that its 14 times heavier .....instead y cant i simply say that nitrogen has 7 protons and 7 neutrons, i.e., 7+7 amu= 14 amu. Basically i want to ask, y do scientist compare it something, y its not simple business of no. of protons+no. of neutrons.(thats what we do in real time,so y definations are confusing ??? )
Standard atomic weight is the average relative atomic mass of an element in the crust ofEarth and its atmosphere. This is what is included in standard periodic tables. Atomic weight is being phased out slowly and being replaced by relative atomic mass. If you will go through the periodic table you will find the atomic mass of nitrogen is not 14, it is 14.0067; of oxygen it is not 8+8= 16 it is rather 15.9994.