What is the formula for magnesium iodide?

1 Answer
Jan 15, 2016

Magnesium metal forms a doubly charged cation. Iodide forms a singly charged anion.


#Mg^(2+) + 2I^(-) rarr MgI_2#

How do you know what ions these elements form? Look at the Periodic Table. Magnesium comes from Group 2; as a metal it needs to lose 2 electrons to assume a Noble Gas configuration (that of neon); on the other hand iodine needs to gain 1 electron to assume the xenon configuration. The ion formation reflects this tendency.

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