An atom has an atomic number of 12 and a mass number of 25. How many neutrons does the atom have?
Simple. The atomic number is the number of protons (12) and the mass number is the number of neutrons and protons combined. So you'd subtract 12 from 25 (25-12=) and that'd get you 13 as your answer. If you need to find the number of electrons, it'll be the same as the number of protons unless it has a certain charge and if it does, if it's positive it has more protons (+) than electrons (-), if it is negative it has more electrons (- negatively charged) than protons (+ positively charged)
The atom have 13 neutrons .
Calculation,
Atomic number = Number of electrons/protons = 12
Mass number = Number of electrons/protons + number of neutrons = 25
Number of neutrons = 25 - Number of electrons/protons
Number of neutrons = 25 - 12 (given) = 13
Mass number is the sum of number of electrons/protons and number of neutrons.
Mass number of calcium is 40 and Atomic number is 20.
Atomic number is the sum of number of electrons/protons.
Example atomic mass of Carbon is 6 , it means carbon atom contains 6 electrons or protons
learn about Mass number
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