What is the charge on the magnesium ion? 2c) What does the charge on the magnesium ion have to do with the number of valence electrons that the neutral element magnesium has? 2d) What is the charge on the iodide ion? 2e) What does the charge on the iodide ion have to do with the number of valence electrons that the element iodine has? 2f) How many iodide ions are needed to cancel out the charge of the magnesium ion? 2g) How is the number of iodide ions needed in Question #2f indicated in the formula?
The Correct Answer and Explanation is:
Correct Answers:
- 2c) The charge on the magnesium ion is +2.
- 2d) The charge on the iodide ion is -1.
- 2f) Two iodide ions are needed to cancel out the charge of one magnesium ion.
- 2g) This is indicated in the formula MgI₂, which shows that two iodide ions combine with one magnesium ion.
Explanation:
Magnesium is a metal found in Group 2 of the periodic table. In its neutral state, a magnesium atom has two electrons in its outermost energy level, or valence shell. These two electrons are not tightly held, so magnesium tends to lose both valence electrons during chemical reactions. When it loses these two electrons, it forms a Mg²⁺ ion. This positive charge comes from the fact that it now has two more protons than electrons.
Iodine, on the other hand, is a non-metal found in Group 17, which means it has seven valence electrons. In order to achieve a full outer shell (which contains eight electrons), iodine needs to gain one electron. When it gains one electron, it becomes an iodide ion (I⁻), with a negative one charge.
To form a stable ionic compound, the positive and negative charges must balance. Since magnesium has a +2 charge and each iodide ion has a -1 charge, it takes two iodide ions to neutralize the +2 charge of one magnesium ion. This 1:2 ratio is reflected in the chemical formula MgI₂, where the subscript “2” indicates there are two iodide ions for every one magnesium ion.
This balance of charges is the basis of ionic bonding, where oppositely charged ions attract each other to form a neutral compound.
