Science Answer In One word.

The element is Fluorine
Its mass number A
= n + p
= 10 + 9 = 19
∴Mass number of Fluorine = 19

The proton is the positively charged particle and its located in the nucleus. Its positive Charge is of the same magnitude as that of the electron’s negative charge.

The number of electrons or protons in an atom is called the atomic number of that atom. It is represented by the letter Z.

Proton, Electron, Neutrons.

An atom is the smallest particle of a chemical element that retains its chemical properties.

It is negatively charged particle, which revolve around the nucleus of the atom is specific orbits.

Protons and neutrons reside in the nucleus of an atom and are thus called nucleons.

The number of electrons present in the outermost shell of an atom are known as valence electrons.

Electron, Proton, Neutron.

Neutron is an elementary particle that carries no charge

It is the sum of protons and neutrons in the nucleus of an atom.

Atomic number is the number of protons, an atom contains.