Question

6 infer the atomic number of barium is 56. what do you know about the subatomic particles in an atom of this element?

Explanation:

1. The atomic number equals the number of protons in a neutral atom, so barium has 56 protons.
2. A neutral atom has equal protons and electrons, so it has 56 electrons.
3. The most common isotope of barium (barium-138) has a mass number of 138. Neutrons are calculated as mass number minus atomic number.

Answer:

• A neutral barium atom has 56 protons in its nucleus.
• A neutral barium atom has 56 electrons orbiting the nucleus.
• For the most abundant isotope (barium-138), the number of neutrons is $138 - 56 = 82$, so it has 82 neutrons in the nucleus.