Q. Mass number of Fe.

Q: What is the mass number of iron?

The mass number A depends on the isotope. For ^{56}\text{Fe}, A=56. For naturally occurring iron, the most common isotope is ^{56}\text{Fe}, so many problems expect 56.

Q: Is the mass number of Fe always 56?

No. Iron has multiple isotopes. ^{54}\text{Fe} has A=54, ^{56}\text{Fe} has A=56, and others exist. Natural iron is mostly ^{56}\text{Fe}.

Q: How do I find mass number from an isotope notation?

In notation ^{A}_{Z}\text{Fe}, the superscript A is the mass number. Example: ^{56}_{26}\text{Fe} means A=56.

Q: What relation connects mass number, protons, and neutrons?

Mass number A equals protons plus neutrons. A = Z + N, where Z is atomic number and N is neutron number.

Q: What is the mass number of \text{Fe} given electron configuration or atomic number only?

Atomic number Z alone is not enough to get A. You need neutron count N or isotope notation (the superscript A).

Q: What does “mass number of Fe” usually mean in typical worksheets?

Usually it means the common isotope ^{56}\text{Fe}, so the expected mass number is 56.

Answer

The mass number of an iron (Fe) atom is the total number of protons plus neutrons. Since iron has atomic number \(26\) (protons), and the common isotope of interest is Fe-56 (which has \(30\) neutrons), the mass number is \(56\).

\[
\text{Mass number of Fe} = 56
\]

Detailed Explanation

To find the mass number of an element, you use this definition:

\[
\text{Mass number } (A)=\text{number of protons } (Z)+\text{number of neutrons } (N)
\]

However, the problem only says “mass number of Fe” and does not mention a specific isotope. For iron, the atomic symbol is \( \text{Fe} \), and iron commonly refers to the most abundant stable isotope:

\[
\text{Fe-56}
\]

That means for this isotope, the mass number is:

\[
A=56
\]

Final answer: The mass number of iron (Fe), using the common isotope Fe-56, is \(56\).

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General Chemistry FAQs

What is the mass number of iron?

The mass number \(A\) depends on the isotope. For \(^{56}\text{Fe}\), \(A=56\). For naturally occurring iron, the most common isotope is \(^{56}\text{Fe}\), so many problems expect \(56\).

Is the mass number of Fe always \(56\)?

No. Iron has multiple isotopes. \(^{54}\text{Fe}\) has \(A=54\), \(^{56}\text{Fe}\) has \(A=56\), and others exist. Natural iron is mostly \(^{56}\text{Fe}\).

How do I find mass number from an isotope notation?

In notation \(^{A}_{Z}\text{Fe}\), the superscript \(A\) is the mass number. Example: \(^{56}_{26}\text{Fe}\) means \(A=56\).

What relation connects mass number, protons, and neutrons?

Mass number \(A\) equals protons plus neutrons. \(A = Z + N\), where \(Z\) is atomic number and \(N\) is neutron number.

If an iron atom has \(26\) protons and \(30\) neutrons, what is its mass number?

\(A = Z + N = 26 + 30 = 56\).

What is the mass number of \(\text{Fe}\) given electron configuration or atomic number only?

Atomic number \(Z\) alone is not enough to get \(A\). You need neutron count \(N\) or isotope notation (the superscript \(A\)).

What does “mass number of Fe” usually mean in typical worksheets?

Usually it means the common isotope \(^{56}\text{Fe}\), so the expected mass number is \(56\).

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