Chapter 3, Problem 30A

Interpretation Introduction

Interpretation: The given table needs to be completed.

Name	Symbol	Atomic number	Mass number	Number of neutrons
	$\text{S}{}_{\text{16}}$
		$19$		$20$
		$10$	$20$
Platinum			$195$
	${}^{244}\text{Pu}$
	${}^{\text{127}}{\text{Te}}_{\text{52}}$
Mercury			$202$
		$20$	$40$
	${}^{\text{77}}\text{Br}{}_{\text{35}}$
Phosphorus				$16$

Concept Introduction :

The number of protons in an atom is called the atomic number. The addition of the number of protons and neutrons, is equal to the mass number. When the numbers of neutrons are different the mass number of element is changes but atomic number remains unchanged that consider as a isotope of the element.

Answer to Problem 30A

The complete table given as -

Name	Symbol	Atomic number	Mass number	Number of neutrons
Sulfur	$\text{S}{}_{\text{16}}$	$\text{16}$	$\text{32}$	$\text{16}$
Potassium	${}^{39}{\text{K}}_{19}$	$19$	$\text{39}$	$20$
Neon	${}^{20}{\text{Ne}}_{10}$	$10$	$20$	$\text{10}$
Platinum	${}^{195}{\text{Pt}}_{78}$	$\text{78}$	$195$	$\text{117}$
Plutonium	${}^{244}\text{Pu}$	$\text{94}$	$\text{244}$	$\text{150}$
Tellurium	${}^{\text{127}}{\text{Te}}_{\text{52}}$	$\text{52}$	$\text{127}$	$\text{75}$
Mercury	${}^{202}\text{Hg}$	$\text{80}$	$202$	$\text{122}$
Calcium	${}^{40}{\text{Ca}}_{20}$	$20$	$40$	$\text{20}$
Bromine	${}^{\text{77}}\text{Br}{}_{\text{35}}$	$\text{35}$	$\text{77}$	$\text{42}$
Phosphorus	${}^{31}{\text{P}}_{15}$	$\text{15}$	$\text{31}$	$16$

Explanation of Solution

Name	Symbol	Atomic number	Mass number	Number of neutrons
Sulfur	$\text{S}{}_{\text{16}}$	$\text{16}$	$\text{32}$	$\text{16}$
Potassium	${}^{39}{\text{K}}_{19}$	$19$	$\text{39}$	$20$
Neon	${}^{20}{\text{Ne}}_{10}$	$10$	$20$	$\text{10}$
Platinum	${}^{195}{\text{Pt}}_{78}$	$\text{78}$	$195$	$\text{117}$
Plutonium	${}^{244}\text{Pu}$	$\text{94}$	$\text{244}$	$\text{150}$
Tellurium	${}^{\text{127}}{\text{Te}}_{\text{52}}$	$\text{52}$	$\text{127}$	$\text{75}$
Mercury	${}^{202}\text{Hg}$	$\text{80}$	$202$	$\text{122}$
Calcium	${}^{40}{\text{Ca}}_{20}$	$20$	$40$	$\text{20}$
Bromine	${}^{\text{77}}\text{Br}{}_{\text{35}}$	$\text{35}$	$\text{77}$	$\text{42}$
Phosphorus	${}^{31}{\text{P}}_{15}$	$\text{15}$	$\text{31}$	$16$

The number of protons is equal to the atomic number of the element.

The mass number= number of protons + number of neutrons.

The number of electrons is equal to the number of protons.

So for the incomplete table −

For the $\text{S}{}_{\text{16}}$

The atomic number= $\text{16}$

The mass number = $\text{32}$

So for the number of neutrons = mass number − number of protons

  $\text{=32-16=16}$

The number of neutrons= $\text{16}$

The element name is sulfur.

For the atomic number = $19$, and number of neutrons= $20$

So the mass number = number of protons+ number of neutrons

  $\text{=19+20=39}$

So the given element is potassium and the symbol is ${}^{39}{\text{K}}_{19}$ .

For the atomic mass= $10$, and mass number = $20$

So for the number of neutrons = mass number − number of protons

  $\text{=20-10=10}$

So the given element is neon and the symbol is ${}^{20}{\text{Ne}}_{10}$ .

For the Platinum The atomic number= $\text{78}$

The mass number = $195$

So for the number of neutrons = mass number − number of protons

  $\text{=195-78=117}$

The number of neutrons= $\text{117}$ , the symbol is ${}^{195}{\text{Pt}}_{78}$ .

For the ${}^{244}\text{Pu}$

The atomic number= $\text{94}$

The mass number = $\text{244}$

So for the number of neutrons = mass number − number of protons

  $\text{=244-94=150}$

The number of neutrons= $\text{150}$ , the element is Plutonium.

For the ${}^{\text{127}}{\text{Te}}_{\text{52}}$

The atomic number= $\text{52}$

The mass number = $\text{127}$

So for the number of neutrons = mass number − number of protons

  $\text{=127-52=75}$

The number of neutrons= $\text{75}$

So the given element is Tellurium.

For the mercury

The atomic number= $\text{80}$

The mass number = $202$

So for the number of neutrons = mass number − number of protons

  $\text{=202-80=122}$

The number of neutrons= $\text{122}$ , the symbol is ${}^{202}\text{Hg}$ .

For the atomic number = $20$, and mass number= $40$

So for the number of neutrons = mass number − number of protons

  $\text{=40-20=20}$

The number of neutrons= $\text{20}$ , the given element is calcium and symbol is ${}^{40}{\text{Ca}}_{20}$ .

For the ${}^{\text{77}}\text{Br}{}_{\text{35}}$

The atomic number= $\text{35}$

The mass number = $\text{77}$

So for the number of neutrons = mass number − number of protons

  $\text{=77-35=42}$

The number of neutrons= $\text{42}$ , the given element is bromine.

For the phosphorus

The atomic number= $\text{15}$

The mass number = $\text{31}$

The number of neutrons= $\text{16}$

So the mass number = number of protons+ number of neutrons

  $\text{=15+16=31}$

So the given element is phosphorus and symbol is ${}^{31}{\text{P}}_{15}$.

Conclusion

The number of neutrons and electrons present in an atom and give the information about the specific elements. The protons are the equal to number of electrons and the numbers of protons are explains the atomic number of the element.