Problem: Naturally occurring boron consists of two isotopes: 10B (19.9%) with an isotopic mass of 10.0129 amu and 11B (80.1%) with an isotopic mass of 11.00931 amu.What is the atomic weight of boron? Check your answer by looking at a periodic table.

🤓 Based on our data, we think this question is relevant for Professor Freitag's class at CREIGHTON.

FREE Expert Solution

We are asked to determine the atomic weight (average molecular mass) of a Boron (B) given 10B (19.9%) with an isotopic mass of 10.0129 amu and 11B (80.1%) with an isotopic mass of 11.00931 amu.


We will solve for Boron's average mass using their abundance. 

The formula for average mass is:

Average molecular mass = (Mass isotope × Fractional Abundance)

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Problem Details

Naturally occurring boron consists of two isotopes: 10B (19.9%) with an isotopic mass of 10.0129 amu and 11B (80.1%) with an isotopic mass of 11.00931 amu.

What is the atomic weight of boron? Check your answer by looking at a periodic table.

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Isotopes concept. You can view video lessons to learn Isotopes. Or if you need more Isotopes practice, you can also practice Isotopes practice problems.

What professor is this problem relevant for?

Based on our data, we think this problem is relevant for Professor Freitag's class at CREIGHTON.