# What compound is formed by two elements which have Z=12, and Z=9 respectively?

Well, if the these are NEUTRAL atoms, then we gots $\text{magnesium fluoride.}$
......$Z = 12$, and $Z = 9$, respectively. Why? Because in the neutral atom there are an equal number of protons, positively charged nucular particles, and electrons, negatively charged EXTRA-nuclear particles.
And so a quick glance at the Periodic Table tells us that we got $M g , Z = 12$, and $F , Z = 9$, respectively. And since these commonly form dication, and monoanion respectively, by addition or subtraction of electrons, we gots......$M g {F}_{2}$.