Question

An iron atom has an atomic number of $26$ and an atomic mass of $55.8$ amu. How many protons does an iron atom have?

Answer 1

An atom is neutral because the total positive charge is equal to the negative charge in an atom. Positive charge is contributed by protons and no of protons is equal to no of electrons which is equal to atomic number $(Z)$ .

Complete step by step answer:
With discovery of electrons scientists started looking for the positively charged particles which were naturally expected because matter is electrically neutral.
This was discovered by Goldestein and protons were discovered. Protons are positively charged particles.
An atom contains protons and electrons in equal proportions. i.e., total number of protons $=$ total number of electrons and this equal to atomic number. $(Z)$
Here atomic number of iron is given
i.e.$26$
it means $Z=26$
Now we know that the atomic number of an atom is equal to protons and electrons.
Atomic Number $(z)=$ Protons $=$ electrons
No of protons in iron $=26$
Final Answer
No of protons in iron atom are $26.$
Electrons are the negatively charged particles that equalize the total no of protons and make the atom neutral.

Note: In a neutral atom, numbers of electrons are always equal to the number of protons.
In a cation, number of electrons $=\text{ }Z\text{ }$ Number of positive charge
In an anion, number of electrons $=Z+$ number of negative charge
Where $Z=$ Atomic number
The stability of the nucleus depends upon the ratio of neutron and proton, if the ratio of neutron and proton increases the stability of the nucleus decreases. Most of the radioactive elements have unstable nuclei and to stabilize their nucleus continuously they emit different types of radiation.