Structure of the Atom


State two observations which show that atom is not indivisible.



Structure of the Atom

Q 1.

Write the limitations of J.J. Thomson's model of an atom.

Q 2.

What are cathode rays?

Q 3.

What were the important features of atomic model based on Rutherford's scattering experiment?

Q 4.

If A = 23 and Z = 11 for Na atom, how many protons, electrons and neutrons present in Na atom?

Q 5.

Who discovered electrons?

Q 6.

What is the mass of proton as compared to electron?

Q 7.

Fill in the blanks :
An atom has mass number 27 and atomic number 13. The atom has _________ electrons, _____ protons and _______ neutrons.

Q 8.

Who discovered protons?

Q 9.

Fill in the blanks :
__________ electrons are located in the outermost shell of an atom.

Q 10.

What are ?-particles?

Q 11.

Fill in the blanks :
The mass number of an atom is equal to the number of ________ in its nucleus.

Q 12.

Fill in the blanks :
Atoms are made up of __________, ___________ and __________.

Q 13.

Fill in the blanks :
Rutherford's scattering experiment is related to to the size of ____________.

Q 14.

Fill in the blanks :
The total number of protons and neutrons in the nucleus of an atom is called its __________.

Q 15.

Who discovered neutrons?

Q 16.

What is Atomic Number? Who coined this term?

Q 17.

Fill in the blanks :
Mass of a proton is __________ times the mass of an electron.

Q 18.

Fill in the blanks :
The maximum number of electrons that can be accommodated in K-shell are _______.

Q 19.

On the basis of Rutherford’s model of an atom, which subatomic particle is present in the nucleus of an atom?

Q 20.

Fill in the blanks :
The _________ of an atom is dense, small in size and is positively charged.

Q 21.

Name the fundamental particle not present in the nucleus of hydrogen atom

Q 22.

Fill in the blanks :
The fundamental sub-atomic particle called neutron was discovered by ___________.

Q 23.

If an atom contains one electron and one proton, will it carry any charge or not?

Q 24.

Write a short note on Nucleus.

Q 25.

Who discovered X-Rays?

Q 26.

Fill in the blanks :
_______ are atoms having the same mass number but different atomic numbers.

Q 27.

Fill in the blanks :
Nucleons are __________ and ___________.

Q 28.

What is mass number?

Q 29.

What is ionization energy?

Q 30.

What are canal rays?

Q 31.

Draw a sketch of Bohr’s model of an atom with three shells.

Q 32.

Fill in the blanks :
Valency is the __________ _____________ of an atom.

Q 33.

Who is known as 'Father of Nucleus Physics'?

Q 34.

Fill in the blanks :
The fundamental particle not present in hydrogen atom is __________.

Q 35.

The total number of electrons in a nitrogen atom is 7. Find the number of valence electrons in it.

Q 36.

Name the radioactive isotope which is used in the treatment of cancer.

Q 37.

Which radioactive isotope is used to determine the activity of thyroid gland ?

Q 38.

What name is given to those isotopes which have unstable nuclei and emit various types of radiations ?

Q 39.

Fill in the following blanks in respect of an atom of an element :
Mass numberAtomic

Q 40.

Complete the following statements :
(a) Magnesium has 2 valence electrons in the......... shell.
(b)The valency of nitrogen in N2 molecule is........
(c)Isotopes have different mass numbers because their nuclei contain different number of........
(d) Some boron atoms have mass number 10 and some have mass number 11. These boron atoms with different mass numbers are called............

Q 41.

(a) What are radioactive isotopes ? Give two examples of radioactive isotopes.
(b)Give any two uses of radioactive isotopes.
(c)An element Z contains two naturally occurring isotopes 3517Z and 3717Z. If the average atomic mass of this element be 35.5 u, calculate the percentage of two isotopes.

Q 42.

Complete the following table.
(i) Symbol__ __ __
(ii) Nature__ __ __
(iii) Relative Charge__ __ __
(iv) Absolute Charge__ __ __
(v) Relative Mass__ __ __
(vi) Absolute Mass__ __ __

Q 43.

Fill in the blanks :
In the three fundamental sub-atomic particles, _________ are negatively charged, _________ are positively charged and ____________ have no charges.

Q 44.

Fill in the blanks :
Atomic number is equal to _____________.

Q 45.

Fill in the blanks :
Co-60 a radio isotope is used in treatment of __________.

Q 46.

What is the maximum number of electrons which can be accommodated in the K shell of an atom

Q 47.

Name the scientist who discovered electron.

Q 48.

Name the positively charged particle present in the atoms of all the element

Q 49.

Which part of an atom was discovered by Rutherford's alpha particle scattering experiment ?

Q 50.

What is the positive charge on the nucleus of an atom due to ?