What is the unit of energy in atomic and nuclear physics? Define it.

(N/A) The unit of energy in atomic and nuclear physics is the electron volt $(eV)$.
Definition: One electron volt $(1 eV)$ is defined as the amount of kinetic energy gained by a single electron when it is accelerated through a potential difference of $1$ volt.
Mathematically,the relationship between electron volt and Joule is:
$1 eV = 1.602 \times 10^{-19} J$
$1 J = 6.242 \times 10^{18} eV$
Table $11.1$: Work function of some metals

Metal	Work function $\phi_{0} (eV)$
$Cs$	$2.14$
$K$	$2.30$
$Na$	$2.75$
$Ca$	$3.20$
$Mo$	$4.17$
$Pb$	$4.25$
$Al$	$4.28$
$Hg$	$4.49$
$Cu$	$4.65$
$Ag$	$4.70$
$Ni$	$5.15$
$Pt$	$5.65$