Answer:
Explanation:
1.138
2. The conversion of an atom of one element into a different element through nuclear changes
3. A nuclear equation is balanced according to mass number. A chemical equation is balanced according to the total mass before and after change
4.82
5. Some of the matter is converted into energy
Considering the definition of atomic number and mass number, an atom of radium has 138 neutrons.
Firts, atom is defined as the smallest particle into which an element can be divided without losing the chemical properties that characterize it.
It is composed of a central part with a positive charge where almost all the mass is concentrated, constituting the atomic nucleus, and by a certain number of negatively charged particles, the electrons, that form the crust.
On the other side, the atomic number is represented by the letter Z and indicates the total number of protons in the nucleus of a given atom.
Finally, the mass number is represented by the letter A and indicates the sum of the number of protons and the number of neutrons in the atomic nucleus. So, the number of protons being equal to the atomic number, the mass number is:
Mass number = (atomic number) + (number of neutrons)
In this case, the element radium has a mass number of 226 and an atomic number of 88. Replacing in the definition of mass number:
226= 88 + number of neutrons
Solving:
226 - 88= number of neutrons
138= number of neutrons
Finally, an atom of radium has 138 neutrons.
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