Based on the electron configuration of the two atoms, predict the ratio of metal cationic (+) atom to nonmetal anionic (-) atom in the compound. Magnesium 1s22s22p63s2
Bromine 1s22s22p63s23p64s23d104p5
A. 1:1
B. 1:2
c. 2:1
D. 3:1

The ratio of metal : B. 1 : 2

Atoms will try to achieve stability such as the electron configuration of the noble gases (octet rule), so that they will release or bind electrons either by ionic or covalent bonds

Magnesium is an alkaline earth metal which is in group 2 which has an atomic number 12.

Electron configuration Mg:  1s²2s²2p⁶3s²

From this electron configuration, Mg will tend to release 2 electrons in the 3s orbital (a configuration like Ne) to form a positive ion (cation) with a +2 charge.

Whereas Bromine is a Halogen element which has atomic number 35 and is in group 17

Electron configuration of Br:  1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁵

From this electron configuration, Br will tend to attract 1 electron to the 4p orbital to form a negative ion (anion) with a charge of -1 (a configuration like Kr)

These two ions will bond with ions and their charges will be crossed to form the compound: MgBr₂

So that the ratio Mg: Br = 1: 2

elements make up everything, and they combine to make compounds.

the answer is c