  Problem solving tips

## Structure Of Atom

- Tricks and Tips to solve difficult problems easily
1
Drawing the spectral lines every time in order to calculate number of spectral lines can be time consuming. Suppose you have to calculate the number of spectral lines when an electron comes from the excited state N = 5 to its original state. When you follow the traditional method, you have to draw out all the possible transitions. But a small trick can help us to calculate spectral lines in no time. In this, you should know the transition state and you are all set. Want to practice? Try these
2
In order to write the electronic configuration of an atom correctly, follow the (n+l) rule. According to which, the orbital with the least value of (n+l) will be filled first with electrons.
But there are exception to this rule. In the electronic configuration of Cr(24) and Cu(29) (image below), the point about extra stability of fully-filled and half-filled configuration takes precedence. Which rule explains the electronic configuration of chromium is [Ar] instead of [Ar]?
A
Pauli's exclusion principle
B
Aufbau Principle
C
Hund's rule
D
Heisenberg principle
3
You can count the number nodes using the simple equations:
• Number of radial nodes = n- 1- l, where n is the principal quantum number and l is the azimuthal quantum number
• Number of angular node = l
• Total number of nodes = Radial nodes + Angular nodes = n-1 Let's practice:
The number of radial nodes and angular nodes for d-orbital can be represented as:
A
(n-2) radial nodes + 1 angular node = (n-1) total nodes
B
(n-1) radial nodes + 1 angular node = (n-1) total nodes
C
(n-3) radial nodes + 2 angular node = (n-l-1) total nodes
D
(n-3) radial nodes + 2 angular node = (n-1) total nodes
Which of the following statements is correct?
A
The total number of nodes in an orbital is .
B
The number of radial nodes in an orbital is .
C
The number of angular nodes in an orbital is .
D
All of the above.