An alpha particle is also known as

$(a)$ What are canal rays? Who discovered them? What is the charge and mass of canal rays?
$(b)$ How are the canal rays different from electrons in terms of charge and mass?

Give reasons for the following:
$(a)$ Isotopes of an element are chemically similar.
$(b)$ An atom is electrically neutral.
$(c)$ Noble gases show least reactivity.
$(d)$ Nucleus of an atom is heavy and positively charged.
$(e)$ Ions are more stable than atoms.

An element $X$ has a mass number $4$ and atomic number $2$. What is the valency of this element?

$(a)$ Explain the Bohr$-$Bury rules for the distribution of electrons into different shells.
$(b)$ Draw the electronic structure of element $X$ with atomic number $17$ and element $Y$ with atomic number $16$.

An ion $Y^{3-}$ contains $18$ electrons and $16$ neutrons. Calculate the atomic number and mass number of the element $Y$. Name the element $Y$.