A scientist discovers a new element on Mars. It has 843 protons, 843 electrons and 992 neutroms. What would be the atomic mass of the new element?
18355
9922
1499
116866
The correct answer and explanation is:
The atomic mass of an element is calculated by adding the number of protons and neutrons in the nucleus, since protons and neutrons contribute most of the atom’s mass. In this case, the element discovered on Mars has 843 protons and 992 neutrons.
To calculate the atomic mass:
- Number of protons = 843
- Number of neutrons = 992
- The number of electrons is not used in calculating the atomic mass, as electrons are much lighter than protons or neutrons.
Thus, the atomic mass is:
Atomic mass=Number of protons+Number of neutrons=843+992=1835\text{Atomic mass} = \text{Number of protons} + \text{Number of neutrons} = 843 + 992 = 1835
The atomic mass of the new element is 1835. However, none of the provided answers are correct, as the expected value should be 1835, which matches the correct sum of protons and neutrons.
Key Points:
- Atomic mass is the sum of protons and neutrons in the nucleus.
- Electrons do not significantly affect the atomic mass because they are so much lighter than protons and neutrons.
- The calculation for the new element’s atomic mass was straightforward once the number of protons and neutrons was known.