Question

Electron transfer is the term for this process. The resulting anion and cation are attracted by Coulombic forces and an ionic compound is formed. Ionic compounds are neutral: the number of electrons lost in forming the cation(s) must equal the number gained in forming the anion(s). For example, Aluminum (Al, Z = 13, Group 3A or 13) will lose 3 electrons to become Al3+ which is isoelectronic with Neon (Ne), its closest noble gas. To form an ionic compound those 3 electrons must be picked up by a nonmetal. Two possibilities are:

• Nitrogen (N, Z = 7, Group 5A or 15) gains all 3 electrons to become isoelectronic with Neon (Z = 10). The compound formed is AlN

• 3 Chlorine atoms (Cl, Z = 17, Group 7A or 17) each gain 1 electron to become isoelectronic with Argon (Ar, Z = 18). The symbol for the compound formed is AlCl3. The subscript after Cl indicates that 3 Cl- anions are required.

1. (1 pt) Form an ionic compound with sodium (Na):

   1. Its atomic number is:

   2. How many electrons must it lose to have the same number of electrons as its nearest noble gas?

   3. Write the symbol for the ion:

   4. Which nonmetal atom needs to gain that same number of electrons to have the same number of electrons as its nearest noble gas?

   5. Write the symbol for the compound formed:

2. (1 pt) Form an ionic compound with calcium (Ca):

   1. Its atomic number is:

   2. How many electrons must it lose to have the same number of electrons as its nearest noble gas?

   3. Write the symbol for the ion:

   4. Which nonmetal atom needs to gain that same number of electrons to have the same number of electrons as its nearest noble gas?

   5. Write the symbol for the compound formed:

Answer 1

1.

Atomic number of Sodium (Na) is 11.

Nearest noble gas is Neon ( atomic number 10).

Hence, Na atom has to lose one electron to attain same number of electrons as Neon.

Symbol of the ion is Na⁺ .

Fluorine needs to gain one electron to have the same number of electrons (10 electrons ) as its nearest noble gas (Ne).

Symbol of ion is F^-.

Symbol of the compound is NaF

2.

Atomic number of Ca is 20.

It has to lose 2 electrons to have same number of electrons as its nearest noble gas ( Argon).

Symbol of ion is Ca²⁺ .

Sulfur atom (Atomic number = 16) needs to gain that same number of electrons as its nearest noble gas .

Symbol of ion is S^-2

Symbol of compound is CaS.