An alkaline earth metal, M, combines with a halide, X. Will the compound be ionic or covalent?

Question

1. Why?
2. What is the formula for this compound?
3. If the halide is found to have 44.73% Cl, what is the empirical formula of the compound?

Answer 1

1. ionic, because alkaline earth metals give an 2e- and halides take 1 e-
2.MX2
3.It could be Sr ,SrCl2

Answer 2

As you can see from your chem book, alkaline earth metals are found in column 2, therefore have +2 ionic charge. Halides are nonmetals found in column 7, therefore have -1 ionic charge.

Metal + nonmetal = ionic bond

Balancing charges, formula will be MX2

Assume that the total mass of the compound is 100g (100%). That means that you can calculate the number of moles of Cl 44.73 g Cl*(1 mol Cl/35.45 g Cl)= 1.26 mol CL

Using the 1:2 ratio of M:X, you know that there will be 0.63 mole M and will have mass of 55.27g.

Molar mass is #grams/#mole therefore molar mass of M= (55.27g/0.63mol)= 87.7 grams per mole

This means that the empirical formula is SrCl2.

Hope you can follow the logic and apply it to your next problem!

Answer 3

The formula will be MX2, and it will be ionic, being the compound of a metal in Group 2 and a non-metal.
If it contains chlorine, it will have the formula MCl2.
Divide 44.73 by 35.5 to get the moles of Cl, then halve that to get the moles of M. This number of moles has mass (100 - 44.73), so you can now identify M by working out its Ar.

Answer 4

MX2 and ionic,100 gr halyde contains 44.73/35.5 mole cl =>158.7 gr halyde contains 1 mole cl2(70 gr cl)158.7-70=88.7gr M=>M=Sr SrCl2 when is the difference in electronegativity between two atoms or elements. Bonds between atoms with a large electronegativity difference (greater than or equal to 1.7) are usually considered to be ionic, while values between 1.7 and 0.4 are considered polar covalent. Values below 0.4 are considered non-polar covalent bonds, and electronegativity differences of 0 indicate a completely non-polar covalent bond.
electronegativity:
Strontium – 0.95 Chlorine – 3.16