Chemistry, asked by sidd2, 1 year ago

calculating atomic mass with atomic number only


sidd2: tell a suitable method only

Answers

Answered by priya24
0
simple ! it's carbon atomic number 6 . it's atomic mass 12.3..!


sidd2: how to calculate
priya24: 6 + 6 is equal to 12 and it's nearly 12.3
sidd2: and of Chlorine
priya24: no it won't match to your question
Answered by kvnmurty
2
It is not always possible to calculate the atomic mass easily by knowing the atomic number of an element.

atomic number = Z = number of protons or electrons.
atomic mass = mass of protons  + mass of  neutrons  in an atom
                    ≈  number of protons + neutrons
Actually neutrons have mass a little more than 1 proton.

For large atoms with high atomic number, the atomic mass is more than the sum of their numbers.  Also the number of neutrons is more than the number of protons in large atoms.

Perhaps there is an empirical relation between atomic number and atomic mass.

atomic mass = 2 * atomic number  for small atoms  (for carbon or smaller)
atomic mass > 2 * atomic number for large atoms.

 Element               Z     mass/Z
=========================

Hydrogen :  H2 :     1        2
Boron        B          5      2.16
Carbon       C         6      2.15
Sodium     Na       11      2.09
Oxygen:     O2      16      1.9999
Chlorine     Cl        17      2.08
Iron            Fe:      25      2.15
Silver         Ag :     42      2.28
                 W       74       2.49
Polonium              84       2.5
Uranium :   U:       92       2.59

The graph between  Z and  mass m  looks like a parabola curving upwards  with central axis being the Y-axis.  You can draw this graph and then for a given value, you can find that from the graph.


kvnmurty: click on thanks button above;; select best answer
priya24: but it is possible in some casess
kvnmurty: I guess a graph like this only can help... perhaps there is an expression for mass M in terms of Z..
kvnmurty: perhaps in some cases, it is possible to estimate..
priya24: what i said is possible in some atoms
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