Order the following compounds according to their expected lattice energies:
MgBr2, AlBr3, LiBr, AlCl3.
Express your answers as chemical formulas. Enter your answers in order of decreasing expected lattice energy separated by commas.

Lattice energy of the ionic compounds takes the following decline in trend: i.e AlCl3, AlBr3, MgBr3, LiBr.

Explanation:

The factors that determine lattice energies of ionic compound are:

Across the period (on the periodic table), Mg has a higher ionic radius (smaller lattice energy) than Al. Conversely from to there is increase in lattice energies caused by increase in ionic radii down the group.

Hence the order of lattice energies from largest to smallest is:

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.