Lithium crystallizes in a cubic unit cell with an edge length of 350. pm. If the density is 0.535 g/cm3, what type of cubic unit cell is seen in lithium

Body-centered cubic

Explanation:

As the edge length of the cubic unit is 350pm, its volume is:

(350x10⁻¹²m)³ = 4.288x10⁻²⁹m³. In cm³

4.288x10⁻²⁹m³ ₓ ([100cm]³ / 1m³) = 4.288x10⁻²³cm³.

As the density of the structure is 0.535g/cm³, the mass of a cubic unir is:

4.288x10⁻²³cm³ ₓ (0.535g / cm³) = 2.29x10⁻²³g,

As atomic mass of Lithium is 6.941g/mol. Mass of 1 atom of Li is:

6.941g/mol ₓ 1mol / 6.022x10²³ atoms = 1.1526x10⁻²³ g / atoms.

Thus, atoms of Li in 2.29x10⁻²³g are:

2.29x10⁻²³g ₓ ( 1 atom / 1.1526x10⁻²³g) = 2 atoms in 1 cubic unit

In body-centered cubic unit cell, there are 2 atoms per cubic unit cell. Thus, structure of Li is:

a electronegativity decreases beacuse the size of nucleus is bigger.