Question

Complete the following table

Element	Atomic number$\left(\mathrm{Z}\right)$	Mass number($\mathrm{A}$)	Number of protons	Number of electrons$\left(\mathrm{e}\right)$	Number of neutrons$\left(\mathrm{n}\right)$
Helium

Answer 1

• The symbol of the element Helium is $\mathrm{He}$.
• The elemental representation of a given element ($\mathrm{He}$) = ${}_2{}^4\mathrm{He}$
• Atomic number of an element is usually written as a subscript on the left-hand side of the chemical symbol. It has the symbol “$\mathrm{Z}$”.
• The atomic number of Helium $=2$
• The atomic number of an atom equals the total number of protons present in the nucleus of an atom
• Number of protons of Helium $=2$
• In a neutral atom, the number of protons equals the number of electrons.
• Number of electrons in Helium $=2$
• The mass number of an element is usually written as a superscript on the left-hand side of the chemical symbol. It has the symbol “$\mathrm{A}$”.
• The mass number of an atom is the total number of protons and neutrons present in the nucleus of an atom.
• The mass number of Helium $=4$
• Number of neutrons present in the atom = Mass number - Atomic number
• The number of neutrons of Helium $=4-2=2$

Element	Atomic number$\left(\mathrm{Z}\right)$	Mass number($\mathrm{A}$)	Number of protons	Number of electrons$\left(\mathrm{e}\right)$	Number of neutrons$\left(\mathrm{n}\right)$
Helium	$2$	$4$	$2$	$2$	$2$