Respuesta :
Considering the definitions of atomic number and mass number, a radium atom has 138 neutrons.
First, an atom is defined as the smallest particle that can break down an element without losing the chemical properties that characterize it.
It consists of a positively charged central part, where almost all mass is concentrated to form the nucleus, and a certain number of negatively charged particles, electrons, which form the crust.
Atomic number, on the other hand, is denoted by the letter Z and indicates the total number of protons in the nucleus of a particular atom.
Finally, mass number is denoted by the letter A and indicates the sum of the number of protons and neutrons in the nucleus. The number of protons equals the atomic number,
In this case, the element radium has a mass number of 226 and an atomic number of 88.
so the mass number is
Mass number = (number of atoms) + (number of neutrons)
226= 88 + number of neutrons
226 - 88 = number of neutrons
138 = number of neutrons
therefore, a radium atom has 138 neutrons.
learn more about neutron here: https://brainly.com/question/5527493
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