The first model of an atom was given by

Find the number of electrons,protons,and neutrons possessed by the alpha particles $\left({ }_{2}^{4} He ^{2+}\right)$ used in the gold leaf experiment.

Why did Rutherford select a gold foil in his $\alpha$-ray scattering experiment?

Which of the following statements about Rutherford's model of the atom are correct?

What was Bohr's postulate on the revolution of electrons in the orbits of an atom?

$(a)$ Both helium and beryllium have two electrons in their valence shells. Helium is a noble gas whereas beryllium is a metal. Justify.
$(b)$ Hydrogen exists in three isotopic forms. Why are the isotopes of hydrogen chemically alike?