Bohr's Model of an Atom

Q.

Write the postulates of Bohrs atom model.

Q.

Write the electronic configuration for $\mathrm{Cr}\left(24\right)\mathrm{and}\mathrm{Cu}\left(29\right)$.

Q. The maximum number of electrons that can be filled in an orbit (shell) can be found by using the formula $2n^2$; where ‘n’ stands for an orbit’s serial number. Calculate the maximum number of electrons that can be accommodated in the $2^{nd}$ orbit (shell) of an atom.

1. 4 electrons
2. 6 electrons
3. 8 electrons
4. 12 electrons

Q.

What are the main postulates of Bohr's atomic theory?

Q.

Why are the electronic configuration numbers the way they are? $\left(2,8,18,32,\dots \right)$ How were they determined?

Q.

Consider 3^rd orbit of He⁺ (Helium), using non-relativistic approach, the speed of electron in this orbit will be $[givenK=9\times {10}^{9}cons\tan t,Z=2andh(Planckscons\tan t)=6.6\times {10}^{-34}Js]$

1. $1.46\times {10}^{6}m/s$

2. $0.73\times {10}^{6}m/s$

3. $3.0\times {10}^{8}m/s$

4. $2.92\times {10}^{6}m/s$

Q.

The maximum number of electrons in an orbit can be calculated by ______ .

1. n²

2. 2n²

3. n

4. 2n

Q.

The capacity of M shell is 18, then why does M shell of calcium has 8 electrons though it's atomic number is 20

Q. What was the source of alpha particles in the Rutherford alpha scattering experiment?

1. Helium nucleus
2. None of these
3. Argon nucleus
4. Hydrogen nucleus

Q.

Radius of atom is of the order of ................ m

Q. Duplet and octet configuration differs in terms of:

1. number of electrons in outermost shell
2. number of electrons in innermost shell
3. number of shells
4. number of protons in outermost shell

Q.

Define isolated atom?

Q.

Why are Bohr orbits called stationary orbits?

Q. The number of atoms in 0.1 mole of tetraatomic gas is

Q. Why electrons don't lose energy even when revolving around the nucleus of the atom?
Is this a contradiction to the electromagnetic theory of physics?

Q.

Why do proton and electron have same charge?

Q.

Justify: "The energy of an electron is quan- tized".

Q.

Identify the names of the scientists who have proposed the model of an atom.

1. J.J. Thomson

2. Rutherford

3. John Dalton

4. Neil Bohr

Q.

.Write the electronic configuration of $\mathrm{K}\&\mathrm{Cl}$.

Q.

What are the two main parts of an atom is composed of ?

Q. What is meant by discrete orbits?

Q. An Atom of an element has 6 proton and 8 electron find its atomic number.

Q.

Which of the following is true for Bohr's model?

1. An electron can move only in those orbits for which its angular momentum is an integral multiple of

2. Electrons revolve around nucleus in discrete and quantized energy levels/orbits.

3. The energy of an electron in the orbit do not change with time.

4. Electron will move from a lower stationary state to a higher stationary state when required amount of energy is absorbed.

Q.

Write the postulates of the Bohr model of an atom.

Q.

Name the scientists who described the arrangement of electrons in an atom?

Q. Identify the names of the scientists who have proposed the model of an atom correctly.

1. J.J. Thomson
2. Rutherford
3. John Dalton
4. Neil Bohr

Q.

(1) As long as an electron revolves in a particular orbit, the electron does not lose its energy. Therefore, these orbits are called stationary orbits and the electrons are said to be in stationary energy states
(2) Each orbit or shell is associated with a definite amount of energy. Hence, these are also called energy levels
(3) An electron jumps from a lower energy level to a higher energy level, by absorbing energy. It jumps from a higher energy level to a lower energy level by emitting energy in the form of electromagnetic radiation
(4) Electrons move around the nucleus in specified circular paths called orbits or shells or energy levels and are designated as K, L, M and N shells respectively

Arrange the above postulates of Bohrs theory in a correct sequence.

1. $4,1,3,2$

2. $4,2,1,3$

3. $4,1,2,3$

4. $2,4,1,3$

Q. Question 16
Which of the following in figure do not represent Bohr's model of an atom correctly?



(a) (i) and (ii)
(b) (ii) and (iii)
(c) (ii) and (iv)
(d) (i) and (iv)

Q.

Describe the observation in the Alpha particle scattering experiment which lead Rutherford to make the following conclusion

(i) Nucleus is positively charged.

(ii) Almost an entire mass of an atom is present in the nucleus of the atom.

(iii) Most of the space in an atom is empty.

Q. What is the maximum number of electrons that can be accommodated in the K-shell of an atom?

1. 10
2. 8
3. 2
4. 18