Question

1. why do we only use the neutrons and protons to find the atomic mass of an atom?
2. write an a.c.e. response confirming or denying the following claim: aluminum has 14 neutrons in its nucleus.

Explanation:

For Question 3:

Electrons have an extremely small mass (approximately $9.109 \times 10^{-31}$ kg) compared to protons ($1.673 \times 10^{-27}$ kg) and neutrons ($1.675 \times 10^{-27}$ kg). This mass is negligible when calculating the total atomic mass, so only protons and neutrons are considered.

For Question 4 (A.C.E. Response):

• Assertion: The claim that aluminum has 14 neutrons in its nucleus is correct.
• Evidence: Aluminum has an atomic number (number of protons) of 13, and its standard atomic mass is approximately 27 amu. The formula for neutrons is $\text{Number of neutrons} = \text{Atomic mass} - \text{Atomic number}$.
• Explanation: Substituting values gives $27 - 13 = 14$, so a neutral aluminum atom has 14 neutrons in its nucleus.

Calculating $27 - 13 = 14$, confirming 14 neutrons in aluminum's nucleus.

Answer:

1. Electrons have negligible mass relative to protons and neutrons, so they do not contribute meaningfully to the total atomic mass, only protons and neutrons are used for the calculation.
2. Assertion: The claim that aluminum has 14 neutrons is correct.

Evidence: Aluminum has atomic number 13, atomic mass ≈27 amu; neutron count = atomic mass - atomic number.