Chapter 3, Problem 27A

Interpretation Introduction

Interpretation:

The atomic number, symbol in the given table needs to be determined.

Atomic number	Symbol	Name
$20$
	$\text{Pt}$
$50$
		Potassium
$35$
	$\text{Cs}$
		Iron

Concept introduction:

The nucleus of an atom is consists by two main subatomic particles, protons and neutrons. The number of protons and neutrons are fixed in an atom. The ratio of subatomic particles are maintains the stability of nucleus.

The atomic number of an atom is equal to the number of protons.

Answer to Problem 27A

The complete table is given as −

Atomic number	Symbol	Name
$20$	$\text{Mn}$	Manganese
$78$	$\text{Pt}$	Platinum
$50$	$\text{Sn}$	Tin
$19$	$\text{K}$	Potassium
$35$	$\text{Br}$	Bromine
$55$	$\text{Cs}$	Caesium
$26$	$\text{Fe}$	Iron

Explanation of Solution

An atom has protons, neutron and electron as the subatomic particle. The nucleus of an atom is consists by two main subatomic particles, protons and neutrons. The protons and electrons are electrically charged but neutrons are neutral.

The mass number of element is the total number of protons and neutrons present in nucleus of an atom.

The atomic number is equal to the number of protons present in atomic nucleus.

The atomic number and the symbol of the elements are given as -

Atomic number	Symbol	Name
$20$	$\text{Mn}$	Manganese
$78$	$\text{Pt}$	Platinum
$50$	$\text{Sn}$	Tin
$19$	$\text{K}$	Potassium
$35$	$\text{Br}$	Bromine
$55$	$\text{Cs}$	Caesium
$26$	$\text{Fe}$	Iron

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 explain the atomic number of the element.