8. What is the mass of 2.31 x 1023 formula units of SrF2?

47.74 g

Explanation:

Given data:

Formula units of SrF₂ = 2.31 ×0²³

Mass of SrF₂ = ?

Solution:

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

1 mole = 6.022 × 10²³ formula units

2.31 ×0²³formula units × 1 mol / 6.022 × 10²³ formula units

0.38 mol

Mass of  SrF₂:

Mass = number of moles × molar mass

Mass = 0.38 mol × 125.62 g/mol

Mass = 47.74 g

"among the transition metal elements, manganese and zinc have a slight lowering of electronegativities. the reason behind this is that the nuclear charges of these elements are slightly weaker than the other transition metal elements due to the way their valence electrons are filled up. both manganese and zinc have their valence electrons filled up to the 4th shell with 1 pair of electrons (4s2) completely occupying it. although the electrons in the 3rd shell (3d) are yet to be paired since the outer most shell is filled up, the ability of the nucleus to attract electrons is lessened. hence,   the electronegativity (or the ability to attract electrons) is lessened."