Question

25 POINTS

Answer 1

EASY AS PIE AND I LIKE PIE

Calcium iodide (CaI2) is an ionic bond, which means that electrons are transferred.  In order for Ca to become the ion Ca2+, the calcium atom must lose 2 electrons. (Electrons have a negative charge, so when an atom loses 2 electrons, its ion becomes more positive.)  In order for I to become the ion I1−, the iodine atom must gain 1 electron. (When an atom gains an electron, its ion will be more negative.)  However, the formula for calcium iodide is CaI2 - there are 2 iodine ions present. This makes sense because the iodine ion has a charge of -1, so two iodine ions have to be present to cancel out the +2 charge of the calcium ion.  Therefore, the calcium atom transfers 2 valence electrons, one to each iodine atom, to form the ionic bond.

IF WRONG, SORRY

Answer 2

Answer: To achieve noble gas configuration and become stable.

Explanation:

Ions are formed when an atom looses or gains electrons.

If an atom gains electrons, it leads to the formation of negative ions known as anions. If an atom looses electrons, it leads to the formation of positive ions known as cations.

As Iodine has atomic number of 53, it contains 53 electrons which are filled according to Afbau's rule as:

$I:53:1s^22s^22p^63s^23p^64s^23d^{10}4p^65s^24d^{10}5p^5$

$I^-:54:1s^22s^22p^63s^23p^64s^23d^{10}4p^65s^24d^{10}5p^6$

As iodine has 7 valence electrons it is valence shell 5 , it is short of one electron to achieve nearest noble gas configuration of Krypton with atomic number of 54. The elements which follow octet rule are considered to be stable and thus iodine accepts electron to form $I^-$