Aufbau Principle

Q.

How to calculate effective nuclear charge and shielding constant for d and f block elements

Please explain with example

Q.

How do you write the electron configuration of scandium?

Q.

Why first shell Is called K shell?

Q.

What is shielding effect and penetration effect ?

Q.

How do you write the electron configuration for ${\mathrm{Ni}}^{2+}$?

Q.

The unpaired electrons in Al and Si are present in 3p orbital. Which electrons will experience more effective nuclear charge from the nucleus?

Q.

The 71^st electron of an element X with an atomic number of 71 enters into the orbital:

1. 4s

2. 5s

3. 5d

4. 6s

Q.

Among the following pairs of orbitals which orbital will experience the larger effective nuclear charge?
(i) 2s and 3s,

(ii) 4d and 4f

(iii) 3d and 3p

Q. Match the following:

Rules	Statements
A) Hund's rule of maximum multiplicity	P) No two electrons in an atom can have the same set of quantum numbers
B) Aufbau principle	Q) Half-filled and completely filled orbitals have extra stability
C) Pauli's exclusion principle	R) Pairing of electrons in the orbitals belonging to the same subshell does not take place until each orbital is singly occupied
D) Hiesenberg's Uncertainity Principle	S) It is impossible to determine the exact position and exact momentum of a subatomic particle simultaneously
	T) In the ground state of atoms, orbitals are filled in the order of their increasing energies

1. $A)-R),B)-T),C)-P),D)-S)$
2. $A)-S),B)-T),C)-Q),D)-R)$
3. $A)-S),B)-P),C)-T),D)-Q)$
4. $A)-R),B)-T),C)-S),D)-P)$

Q. If the electronic configuration of oxygen atom is written as
it would violate :

1. Hund's rule
2. Pauli's exclusion principle
3. Both Hund's & Pauli's principles
4. None of these

Q.

How Do You Fill Orbitals?

Q.

Fill in the blanks-

Halogens have high

Q. What is the spin-only magnetic moment value (BM) of a divalent metal ion with atomic number 25, in its aqueous solution?

1. 5.92
2. 5.26
3. Zero
4. 5.0

Q.

Is electron gain enthalpy inversely proportional to the atomic radius?

Q. According to Bohr's theory, which of the following correctly represents the variation of energy and radius of an electron in $n^{th}$ orbit of H-atom?

1. $E_n\propto \frac{1}{n^2},r\propto \frac{1}{n^2}$
2. $E_n\propto \frac{1}{n^2},r\propto n^2$
3. $E_n\propto n^2,r\propto n^2$
4. $E_n\propto n,r\propto \frac{1}{n}$

Q.

What is the lowest energy state of an atom called?

Q.

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

Q. Consider the ground state of $Cr$ atom $(z=24)$. The number of electrons with the azimuthal quantum numbers, $l=1$ and 2 are, respectively

1. 16 and 4
2. 12 and 5
3. 16 and 5
4. 12 and 4

Q.

What is violation of the Pauli exclusion principle?

Q. Which one of the following ions has an electronic configuration of $\left[Ar\right]3d^6$ ?
$(AtomicNumber:Mn=25,Fe=26,Co=27,Ni=28)$

1. $M{n}^{3+}$
2. $F{e}^{3+}$
3. $N{i}^{3+}$
4. $C{o}^{3+}$

Q.

How many electrons and protons are there in a carbon atom?

Q.

In BF${}_3$

1. All the B - F Bond are single covalents in nature

2. Boron-fluorine bond has some double bond character and this bond is delocalised

3. Bond energy and bond length of B - F bond indicate its single bond character

4. All the bond are ionic

Q.

Electrons revolve around the nucleus in definite orbits called _________.

Q.

What is the electron configuration for a phosphorous anion with a charge of $-2$?

Q.

Calculate the ‘spin only’ magnetic moment of M²⁺_(aq) ion (Z = 27).

Q. Why does heat of atomisation decreases down the group in alkali metal?

Q. How many shells, orbitals and electrons are there in an atom having atomic mass 24 and atomic number 12 respectively?

1. 3, 4, 12
2. 4, 3, 12
3. 6, 3, 12
4. 3, 6, 12

Q. In $Cu$ (Atomic No. 29)

1. 13 electrons have spin in one direction and 16 electrons in other direction
2. 14 electrons have spin in one direction and 15 electrons in other direction
3. Total spin , $S=\frac{1}{2}$
4. Spin magnetic moment is $\sqrt{3}B.M.$

Q. If the azimuthal quantum number could have the value of $n$ also then:

1. $Sc(Z=21)$ would have configuration as $1s^{2}1p^{6}2s^{2}2p^{6}2d^{3}3s^2$
2. $Fe(Z=26)$ would have two unpaired electrons
3. $F{e}^{2+}$ and $F{e}^{3+}$ would be paramagnetic and coloured
4. $C{u}^{+}$ would be coloured and paramagnetic

Q. Which is the correct order of increasing energy of the listed orbitals in the atom of titanium ? (At. no. $Z=22$)

1. $3s3p3d4s$
2. $3s3p4s3d$
3. $3s4s3p3d$
4. $4s3s3p3d$