How many neutrons are in a typical lithium atom with an atomic mass of 7?

• A. 7
• B. 10
• C. 3
• D. 4

Answer: (D)

Verified step by step guidance

1. Identify the atomic number of lithium, which is 3. This tells us the number of protons in a lithium atom.
2. Understand that the atomic mass of lithium is given as 7. This is the sum of the number of protons and neutrons in the atom.
3. Use the formula: \( \text{Number of neutrons} = \text{Atomic mass} - \text{Atomic number} \).
4. Substitute the known values into the formula: \( \text{Number of neutrons} = 7 - 3 \).
5. Calculate the result to find the number of neutrons in a typical lithium atom.