Q. 6.3 - An Introduction to General, Organic, and Biological Chemistry

Question

State the number of electrons lost or gained when the following elements form ions:

a. Sr      b. P      c. Group $7A\left(17\right)$      d. Na      e. Br

Step-by-Step Solution

Answer

(part a) In the form of ion $S{r}^{2+}$, strontium lost $2$ electrons.

(part b) In the form of ion, phosphorus gained $3$ electrons.

(part c) In the form of ions $F^{-}, C{l}^{-}, B{r}^{-}$ and $I^{-}$, group $7A\left(17\right)$ gained $1$ electron.

(part d) In the form of ion $N{a}^{+}$, sodium lost $1$ electron.

(part e) In the form of ion $B{r}^{-}$, bromine gained $1$ electron.

Step 1: Introduction (part a)

The given is Sr.

We have to find the number of electrons gained or lost by Sr.

Step 2: Explanation (part a)

(part a) Strontium is a chemical element with the symbol Sr. Strontium has an atomic number of $38$ and belongs to group $2A\left(2\right)$. Strontium (Sr) loses two electrons to obtain the nearest noble gas electron arrangement krypton (kr), which has eight electrons in its octet.

As a result, strontium lost two electrons and became the ion $S{r}^{2+}$.

Step 3: Introduction (part b)

The given is P.

We have to find the number of electrons gained or lost by P.

Step 4: Explanation (part b)

(part b) Phosphorus is a chemical element with the symbol P. Phosphorus has an atomic number of $15$ and belongs to group $5A\left(15\right)$. Phosphorus (P) gains three electrons to obtain the nearest noble gas electron arrangement argon (Ar), which has eight electrons in its octet.

As a result, Phosphorus gained three electrons and became the ion.

Step 5: Introduction (part c)

The given is Group $7A\left(17\right)$.

We have to find the number of electrons gained or lost by Group $7A\left(17\right)$.

Step 6: Explanation (part c)

(part c) Fluorine, Chlorine, Bromine, and Iodine are the elements in group $7A\left(17\right)$. All of these elements gain one electron in order to obtain the nearest noble gas electron arrangement, which has eight electrons in its octet.

As a result, group $7A\left(17\right)$ gained 1 electron, resulting in the ions $F^{-},C{l}^{-},B{r}^{-}$ and $I^{-}$

Step 7: Introduction (part d)

The given is Na.

We have to find the number of electrons gained or lost by Na.

Step 8: Explanation (part d)

(part d) Sodium is a chemical element with the symbol Na. Strontium has an atomic number of $11$and belongs to group $1A\left(1\right)$. Sodium(Na) loses one electron to obtain the nearest noble gas electron arrangement neon(Ne) , which has eight electrons in its octet.

As a result, sodium lost one electron and became the ion $N{a}^{+}$.

Step 9: Introduction (part e)

The given is Br.

We have to find the number of electrons gained or lost by Br.

Step 10: Explanation (part e)

(part e) Bromine is a chemical element with the symbol Br. Bromine has an atomic number of $35$ and belongs to group $7A\left(17\right)$. Bromine (Br) gains one  electron to obtain the nearest noble gas electron arrangement krypton (kr), which has eight electrons in its octet.

As a result, Bromine gained one electron and became the ion $B{r}^{-}$