How many neutrons and protons are there inthe following nuclei?

Solution:

${ }^{13}{ }_{6} \mathrm{C}:$

Atomic mass $=13$

Atomic number $=$ Number of protons $=6$

Number of neutrons $=$ (Atomic mass) $-$ (Atomic number)

$=13-6=7$

${ }_{8}^{16} \bigcirc$

Atomic mass $=16$

Atomic number $=8$

Number of protons $=8$

Number of neutrons $=$ (Atomic mass) $-$ (Atomic number)

$=16-8=8$

${ }_{12}^{24} \mathrm{Mg}$ :

Atomic mass $=24$

Atomic number $=$ Number of protons $=12$

Number of neutrons $=$ (Atomic mass) $-$ (Atomic number)

$=56-26=30$

${ }_{25}^{56} \mathrm{Fe}:$

Atomic mass $=56$

Atomic number $=$ Number of protons $=26$

Number of neutrons = (Atomic mass) - (Atomic number)

$=56-26=30$

${ }_{38}^{88} \mathrm{Sr} \quad:$

Atomic mass $=88$

Atomic number $=$ Number of protons $=38$

Number of neutrons $=$ (Atomic mass) $-$ (Atomic number)

$=88-38=50$