A **body-centered cubic (BCC) unit cell** is composed of a cube with one atom at each of its corners and one atom at the center of the cube.

*Recall the # of atoms present **per 1 BCC unit cell*: *corner atoms contribute 1/8 and the center atom contribute 1*

$\mathbf{\#}\mathbf{}\mathbf{of}\mathbf{}\mathbf{atoms}\mathbf{=}\left(\mathbf{8}\mathbf{\times}\frac{\mathbf{1}}{\mathbf{8}}\right)\mathbf{+}\mathbf{1}$

**# of atoms = 2 per 1 unit cell**

**To calculate Avogadro's number: (# of entities in 1 mole)**

**Step 1: Volume of unit cell**

$\mathbf{volume}\mathbf{}\mathbf{of}\mathbf{}\mathbf{unit}\mathbf{}\mathbf{cell}\mathbf{=}\mathbf{volume}\mathbf{}\mathbf{of}\mathbf{}\mathbf{a}\mathbf{}\mathbf{cube}\phantom{\rule{0ex}{0ex}}\overline{){\mathbf{volume}}{\mathbf{}}{\mathbf{of}}{\mathbf{}}{\mathbf{unit}}{\mathbf{}}{\mathbf{cell}}{\mathbf{=}}{{\mathbf{a}}}^{{\mathbf{3}}}}\phantom{\rule{0ex}{0ex}}\mathbf{volume}\mathbf{}\mathbf{of}\mathbf{}\mathbf{unit}\mathbf{}\mathbf{cell}\mathbf{}\mathbf{=}\mathbf{}{\mathbf{(}\mathbf{3}\mathbf{.}\mathbf{3058}\mathbf{}\overline{)\mathbf{\AA}}\mathbf{\times}\frac{{\mathbf{10}}^{\mathbf{-}\mathbf{10}}\mathbf{}\overline{)\mathbf{m}}}{\mathbf{1}\mathbf{}\overline{)\mathbf{\AA}}}\mathbf{\times}\frac{\mathbf{1}\mathbf{}\mathbf{cm}}{{\mathbf{10}}^{\mathbf{-}\mathbf{2}}\mathbf{}\overline{)\mathbf{m}}}\mathbf{)}}^{\mathbf{3}}$

**volume of unit cell = 3.61268 x 10 ^{-23} cm^{3}**

Tantalum (Ta; *d* = 16.634 g/cm^{3} and ℳ = 180.9479 g/mol) has a body-centered cubic structure with a unit-cell edge length of 3.3058 Å. Use these data to calculate Avogadro’s number.

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 Unit Cell concept. You can view video lessons to learn Unit Cell. Or if you need more Unit Cell practice, you can also practice Unit Cell practice problems.

What professor is this problem relevant for?

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

What textbook is this problem found in?

Our data indicates that this problem or a close variation was asked in Chemistry: The Molecular Nature of Matter and Change - Silberberg 8th Edition. You can also practice Chemistry: The Molecular Nature of Matter and Change - Silberberg 8th Edition practice problems.