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?
2b) 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:
2b) The charge on the magnesium ion is +2.
2c) The charge on the magnesium ion is related to the number of valence electrons in a neutral magnesium atom. Magnesium is in Group 2 of the periodic table and has 2 valence electrons. It loses these two electrons to achieve a full outer shell, forming a Mg²⁺ ion with a +2 charge.
2d) The charge on the iodide ion is −1.
2e) The charge on the iodide ion is related to the number of valence electrons in a neutral iodine atom. Iodine is in Group 17 and has 7 valence electrons. It gains 1 electron to complete its octet, forming an I⁻ ion with a −1 charge.
2f) To cancel out the +2 charge of the magnesium ion, 2 iodide ions (each with a −1 charge) are needed. This is because two −1 charges are required to balance one +2 charge.
2g) The number of iodide ions needed is shown in the chemical formula as a subscript: MgI₂. This indicates that two iodide ions are bonded to one magnesium ion.
Explanation (300 words):
The behavior of elements during ion formation depends on the arrangement of electrons, particularly in the outermost shell called the valence shell. Magnesium (Mg) is a metal found in Group 2 of the periodic table. It has two electrons in its valence shell. To become stable, magnesium tends to lose these two electrons, resulting in a positively charged ion known as Mg²⁺. This means it has two more protons than electrons, giving it a charge of +2.
On the other hand, iodine (I) is a nonmetal located in Group 17. It has seven valence electrons and needs just one more to complete its octet, making it chemically stable. Therefore, iodine tends to gain one electron, forming a negatively charged ion I⁻ with a charge of −1.
When magnesium and iodine react to form a compound, the charges on their ions must balance out. Since one magnesium ion has a +2 charge and one iodide ion has a −1 charge, you need two iodide ions to cancel out the +2 charge of one magnesium ion. This gives a neutral compound overall.
The correct ratio is shown in the chemical formula MgI₂, where the subscript “₂” after the I represents the number of iodide ions needed. There is no subscript for magnesium because there is only one magnesium ion. This balanced formula ensures that the total positive charge (+2) and total negative charge (−2 from two I⁻ ions) equal zero, which is a requirement for all stable ionic compounds.
