Chapter 3

An atom of an element has 13 electrons. Its nucleus has 14 neutrons. Find out atomic no. and approximate atomic weight. Indicate the arrangement of electrons and the electrovalency of the element.

A neutral atom of an element has \(2 K, 8 L, 9 M\) and \(2 N\) electrons. Find out the following: (a) Atomic no., (b) Total no. of \(s\) -electrons, (c) Total no. of \(p\) -electrons, (d) Total no. of \(d\) -electrons, (e) Valency of element, (f) No. of unpaired electrons.

The sodium flame test has a characteristic yellow colour due to emissions of wavelength \(589 \mathrm{~nm}\). What is the mass equivalence of one photon of this wavelength?

$$ \text { Write electronic configuration of } \mathrm{Fe}^{2+}, \mathrm{Mn}^{4+}, \mathrm{N}^{3-} \text { and } \mathrm{O}^{2-} \text { ions. } $$

What is the maximum number of emission lines when the excited electron of a H-atom in \(n=6\) drops to the ground state?

What is the significance of \(\psi_{210}\). Find out angular momentum, spherical nodes and angular node for \(\psi_{210}\).