Q. 4.35 - An Introduction to General, Organic, and Biological Chemistry

Question

Write the atomic symbol for the isotope with each of the following characteristics:

a. $15$ protons and $16$ neutrons

b. $35$ protons and $45$ neutrons

c. $50$ electrons and $72$ neutrons

d. A chlorine atom with $18$ neutrons

e. A mercury atom with $122$ neutrons

Step-by-Step Solution

Answer

(a) The required atomic symbol is, ${}_{15}{}^{31}P$

(b) The required atomic symbol is, ${}_{35}{}^{80}Br$

(c) The required atomic symbol is, ${}_{50}{}^{122}Sn$

(d) The required atomic symbol is, ${}_{17}{}^{35}Cl$

(e) The required atomic symbol is, ${}_{80}{}^{202}Hg$

Part (a) Step 1: Given information

We need to find out the atomic symbol of the isotope having $15$ protons and $16$ neutrons

Part (a) Step 2: Simplify

We know that,

No. of protons are equal to atomic no. of the element.

So, atomic no. is, $Z=15$

And mass no. is equal to the sum of no. of protons and no. of neutrons

Therefore, mass no. is, $A=15+16=31$

Also, standard representation of an element is, ${}_Z{}^{A}X$

Here, $X$ is $P$(Phosphorous)

Hence, the required atomic symbol is,  ${}_{15}{}^{31}P$

Part (b) Step 1: Given information

We need to find out the atomic symbol of the isotope having $35$ protons and $45$ neutrons 

Part (b) Step 2: Simplify

We know that,

No. of protons are equal to atomic no. of the element.

So, atomic no. is, $Z=35$

And mass no. is equal to the sum of no. of protons and no. of neutrons

Therefore, mass no. is, $A=35+45=80$

Also, standard representation of an element is, ${}_Z{}^{A}X$

Here, $X$ is $Br$(Bromine)

Hence, the required atomic symbol is, ${}_{35}{}^{80}Br$

Part (c) Step 1: Given information

We need to find out the atomic symbol of the isotope having $50$ electrons and $72$ neutrons 

Part (c) Step 2: Simplify

We know that,

No. of electrons are equal to atomic no. of the element.

So, atomic no. is, $Z=50$

And mass no. is equal to the sum of no. of protons and no. of neutrons

Therefore, mass no. is, $A=50+72=122$

Also, standard representation of an element is, ${}_Z{}^{A}X$

Here, $X$ is $Sn$

Hence, the required atomic symbol is, ${}_{50}{}^{122}Sn$

Part (d) Step 1: Given information

We need to find out the atomic symbol of the chlorine atom having $18$ neutrons 

Part (d) Step 2: Simplify

We know that,

Atomic no. of chlorine atom is, $Z=17$

And mass no. is equal to the sum of no. of protons and no. of neutrons

Therefore, mass no. is, $A=17+18=35$

Also, standard representation of an element is, ${}_Z{}^{A}X$

Hence, the required atomic symbol is, ${}_{17}{}^{35}Cl$

Part (e) Step 1: Given information

We need to find out the atomic symbol of the mercury atom having $122$ neutrons  

Part (e) Step 2: Simplify

We know that,

Atomic no. of mercury atom is, $Z=80$

And mass no. is equal to the sum of no. of protons and no. of neutrons

Therefore, mass no. is, $A=80+122=202$

Also, standard representation of an element is, ${}_Z{}^{A}X$

Hence, the required atomic symbol is, ${}_{80}{}^{202}Hg$