Write down the electron distribution of chlorine atom. How many electrons are there in the $L$ shell? (Atomic number of chlorine is $17$).

In the Thomson's model of atom,which of the following statements are correct?
$(i)$ The mass of the atom is assumed to be uniformly distributed over the atom.
$(ii)$ The positive charge is assumed to be uniformly distributed over the atom.
$(iii)$ The electrons are uniformly distributed in the positively charged sphere.
$(iv)$ The electrons attract each other to stabilize the atom.

The first model of an atom was given by

An atom of an element has full $K$ and $L$ shells and has $5$ electrons in its $M$ shell. What is its atomic number?

What do you understand by an octet of electrons in the valence shell?

Elements with valency $1$ are