Q. Magnesium atomic weight.

Q: What is the atomic weight (relative atomic mass) of magnesium, \mathrm{Mg} ?

Magnesium has relative atomic mass \approx 24.305 \, \mathrm{u} (often rounded to 24.3).

Q: What is magnesium’s molar mass in \mathrm{g\,mol^{-1}} ?

Numerically it matches atomic weight: M \approx 24.305 \, \mathrm{g\,mol^{-1}} .

Q: How do isotopes affect magnesium’s atomic weight?

Natural magnesium is mainly ^{24}\mathrm{Mg}, ^{25}\mathrm{Mg}, ^{26}\mathrm{Mg}; the atomic weight is the weighted average by their percent abundances.

Q: What percent abundance values are commonly used for magnesium isotopes?

Typical: ^{24}\mathrm{Mg}\approx 78.99\%, ^{25}\mathrm{Mg}\approx 10.00\%, ^{26}\mathrm{Mg}\approx 11.01\%.

Answer

Magnesium’s atomic weight means its average atomic mass based on natural isotopes. The standard periodic-table value for magnesium is about \(24.305\ \text{amu}\).

\[ \text{Atomic weight of Mg} = 24.305\ \text{amu} \ (\approx 24.31) \]

Detailed Explanation

Let’s solve the question: “Magnesium atomic weight.” In chemistry, “atomic weight” usually means the atomic mass of an element as it appears on the periodic table (taking natural isotopic abundance into account).

Step 1: Understand what “atomic weight” refers to

Magnesium (element symbol: Mg) has multiple naturally occurring isotopes. The periodic-table value is a weighted average of the isotopic masses based on their natural abundances.

Step 2: Use the standard periodic-table value for magnesium

The commonly accepted value for magnesium’s atomic weight is:

\[
\text{Atomic weight of Mg} = 24.305\ \text{u}
\]

Step 3: State the final answer clearly

The atomic weight (atomic mass) of magnesium is approximately 24.305 u.

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General Chemistry FAQs

What is the atomic weight (relative atomic mass) of magnesium, \( \mathrm{Mg} \)?

Magnesium has relative atomic mass \( \approx 24.305 \, \mathrm{u} \) (often rounded to \(24.3\)).

What is the atomic number of magnesium, \( \mathrm{Mg} \)?

The atomic number is \( Z = 12 \).

What is magnesium’s molar mass in \( \mathrm{g\,mol^{-1}} \)?

Numerically it matches atomic weight: \( M \approx 24.305 \, \mathrm{g\,mol^{-1}} \).

How do isotopes affect magnesium’s atomic weight?

Natural magnesium is mainly \(^{24}\mathrm{Mg}\), \(^{25}\mathrm{Mg}\), \(^{26}\mathrm{Mg}\); the atomic weight is the weighted average by their percent abundances.

What percent abundance values are commonly used for magnesium isotopes?

Typical: \(^{24}\mathrm{Mg}\approx 78.99\%\), \(^{25}\mathrm{Mg}\approx 10.00\%\), \(^{26}\mathrm{Mg}\approx 11.01\%\).

What is the weighted-average calculation for magnesium’s atomic weight?

\( \displaystyle (24\times0.7899)+(25\times0.1000)+(26\times0.1101)\approx 24.305 \, \mathrm{u} \).

If magnesium is \( \mathrm{Mg} \), what is its mass per atom in grams?

\( \displaystyle m=\frac{24.305\,\mathrm{g\,mol^{-1}}}{N_A}\approx \frac{24.305}{6.022\times10^{23}}\,\mathrm{g} \approx 4.04\times10^{-23}\,\mathrm{g}. \)

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