Q. 4.83 - An Introduction to General, Organic, and Biological Chemistry

Question

Indicate if the atoms in each pair have the same number of protons, neutrons or electrons. $(4.4 ,4.5 )$

a. ${}_{17}{}^{37}CI , {}_{18}{}^{38}Ar$

b. ${}_{16}{}^{36}S , {}_{16}{}^{34}S$

c. ${}_{18}{}^{40}Ar , {}_{17}{}^{39}CI$

Step-by-Step Solution

Answer

a. In the pair ${}_{17}{}^{37}CI , {}_{18}{}^{38}Ar$ is the same number of neutrons but not the same number of protons and electrons.

b. In the pair ${}_{16}{}^{36}S , {}_{16}{}^{34}S$  is the same number of protons and electrons but the not same number of neutrons.

c. In the pair  ${}_{18}{}^{40}Ar , {}_{17}{}^{39}CI$ is the same number of neutrons  but not the same number of protons and electrons.

Part (a) step 1: Given Information

We have to show whether the atoms in each pair have the same number of protons, neutrons or electrons or not.

Part (a) step 2: Simplify

The standard form is ${}_z{}^{A}X$

A is the atomic mass

Z is the atomic number 

Z is the element name.

Here, we have  ${}_{17}{}^{37}CI$ and ${}_{18}{}^{38}Ar$ the same number of protons, electrons or neutrons. The atomic number alone, we can conclude that the two-element do not have the same number of protons and electrons.

Now, 

Subtract the atomic number from the atomic mass:

So, ${}_{17}{}^{37}CI$ is,

Neutrons $= A-Z$

Neutrons $$\begin{gathered} =37-17 \\ =20 \end{gathered}$$

And,

${}_{18}{}^{38}Ar$ is:

Neutrons $=A-Z$

Neutrons $$\begin{gathered} =38-18 \\ =20 \end{gathered}$$

The pair ${}_{17}{}^{37}CI , {}_{18}{}^{38}Ar$ has the same number of neutrons.

Part (b) step 1: Given Information

We have to show whether the atoms in each pair have the same number of protons, neutrons or electrons or not. 

Part (b) step 2: Simplify

The standard form is ${}_z{}^{A}X$

A is the atomic mass

Z is the atomic number 

Z is the element name.

Here, we have ${}_{16}{}^{36}S , {}_{16}{}^{34}S$ he same number of protons, electrons or neutrons. The atomic number alone, we can conclude that the two-element have the same number of protons and electrons. which is $16$.

Now, 

Subtract the atomic number from the atomic mass:

So, ${}_{16}{}^{36}S$ is

Neutrons $=A-Z$

Neutrons $$\begin{gathered} =36-16 \\ =20 \end{gathered}$$

${}_{16}{}^{34}Ar$ is:

Neutrons $=A-Z$

Neutrons $$\begin{gathered} =34-16 \\ =18 \end{gathered}$$

The pair ${}_{16}{}^{36}S , {}_{16}{}^{34}S$ has not the same number of neutrons.

Part (c) step 1: Given Information

We have to show whether the atoms in each pair have the same number of protons, neutrons or electrons or not. 

Part (c) step 2: Simplify

The standard form is ${}_z{}^{A}X$

A is the atomic mass

Z is the atomic number 

Z is the element name.

Here, we have ${}_{18}{}^{40}Ar , {}_{17}{}^{39}CI$ the number on the upper left is the mass number while the number below is the atomic number. The mass number is equal to the number of protons and neutrons in the nucleus, atomic number is equal to the number of protons and electrons.

Now, the number of neutrons so:

Number of neutrons = $mass number -atomic number$

Number of neutrons (Ar) $$\begin{gathered} =40-18 \\ =22 \end{gathered}$$

Number of neutrons (CI) $$\begin{gathered} =39-17 \\ =22 \end{gathered}$$

Now, make a table:

	Mass number	protons	neutrons	electrons
Ar	40	18	22	18
CI	39	17	22	17