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Physics A specimen paper - Q1

(a) How many protons, neutrons and electrons are there in an atom of caesium, mass number: 133 and atomic number: 55 of Cs,
which is the most abundant and stable isotope of caesium.
......................... protons
........................neutrons
.......................electrons

In the mark scheme, it says 55 protons, 55 electrons and 82 neutrons? :eek3:

How is 82 neutrons possible? isnt it suppose to be 78 neutrons? :s-smilie:

Reply 1

apo1324

Its an isotope thats why...

Isotopes are different atomic forms of the same element with the same number of protons but a different number of neutrons.