How do you get the Neutrons from just looking at the periodic table?

Question

thank you.

Answer 1

Be careful! Usually you don't! If you look at Hydrogen it'll say something like 1.008. Well, a proton and an electron are 1.0000 so what is that extra .008 for? Because hydrogen with a neutron (deuterium) is a rare but naturally occurring phenomenon, and a little hydrogen with TWO neutrons also occurs naturally (tritium).

So those atomic weights are AVERAGES of ALL THE ISOTOPES and most elements have multiple isotopes (= different numbers of neutrons).

I think the Handbook of Chemistry and Physics will give you the isotopes and relative frequency per isotope of the elements. the periodic table gives you AVERAGES for each element as it occurs on earth.

BTW, ever wonder how we tell whether an asteroid came from mars or venus or mercury? The relative mix of isotopes is unique for each planet. A periodic table for mars or venus or mercury or fragmetns of the asteroid belt would be DIFFERENT than ours respecting that "average" mass figure for each element.

Answer 2

Neutrons = Atomic Mass - Atomic Number
Protons = Atomic Number
Electrons = Atomic number.

Answer 3

Atomic weight minus atomic number equals neutrons. :) Atomic number equals the protons and equals the electrons.

Answer 4

in an periodic table atomic no.[z] & mass no.[a] are given.so we get the no of neutrons by a-z as a=the no. of protons+neutrons & z=the no. of protons . so:
no. protons +no. neutrons -no. protons = no.of neutrons

Answer 5

i might be wrong on this, but i think the element number (eg, Hydrogen is 1) might tell you the number of neutrons, or it might be atomic molar mass minus the element number

Answer 6

subtract the atomic # from the atomic mass #

Answer 7

subtract the chemical no. from the weight. it is mostly accurate.