Multiple Choice
Thallium has atomic number 81. How many neutrons are in an atom of thallium-205 (Tl-205)?
4. Atoms and Elements
Isotopes
Multiple Choice
How many neutrons are in a neutral atom of sodium-23, ?
A
B
C
D
Verified step by step guidance1
Identify the atomic number (Z) of sodium, which is the number of protons in the nucleus. For sodium, Z = 11.
Recognize that the mass number (A) of sodium-23 is 23. The mass number represents the total number of protons and neutrons in the nucleus.
Recall that the number of neutrons (N) can be found by subtracting the atomic number from the mass number using the formula: \(N = A - Z\).
Substitute the known values into the formula: \(N = 23 - 11\).
Calculate the difference to find the number of neutrons in the sodium-23 atom.
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