Chemistry

Structure of the Atom

Question:

What is mass number?

Answer:

Mass number (A) is equal to number of nucleons present inside the nucleus. It
means it is the sum of number of protons and neutrons present in the nucleus of an atom. It is
denoted by letter A.
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Structure of the Atom

Q 1.

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

Q 2.

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

Q 3.

What is the mass of proton as compared to electron?

Q 4.

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

Q 5.

What are cathode rays?

Q 6.

Who discovered protons?

Q 7.

Who discovered electrons?

Q 8.

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

Q 9.

What are ?-particles?

Q 10.

What is Atomic Number? Who coined this term?

Q 11.

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

Q 12.

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

Q 13.

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

Q 14.

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

Q 15.

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

Q 16.

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

Q 17.

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

Q 18.

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

Q 19.

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

Q 20.

Who discovered neutrons?

Q 21.

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

Q 22.

Write a short note on Nucleus.

Q 23.

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

Q 24.

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

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 are canal rays?

Q 29.

What is ionization energy?

Q 30.

What is mass number?

Q 31.

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

Q 32.

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

Q 33.

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

Q 34.

What is the electronic configuration of a hydrogen atom

Q 35.

Given that the percentage abundance of the isotope 2010Ne, is 90% and that of the isotope 2210Ne, is 10%,calculate the average atomic mass of neon.

Q 36.

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

Q 37.

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 38.

State the location of electrons, protons and neutrons in an atom.

Q 39.

State one use of radioactive isotopes in industry.

Q 40.

State whether the following statement is true or false :
Radioactive isotope of iodine is used for making the medicine called tincture iodine.

Q 41.

What name is given to those atoms which contain the same number of protons and electrons but different number of neutrons ?

Q 42.

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

Q 43.

Name the shell of an atom which can accommodate a maximum of
(a) 2 electrons (b) 18 electrons

Q 44.

What is a proton ? How does it differ from a neutron ?

Q 45.

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

Q 46.

What are the limitations of Rutherford’s model of the atom?

Q 47.

What do you think would be the observation if the ?-particle scattering experiment is carried out using a foil of a metal other than gold?

Q 48.

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

Q 49.

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

Q 50.

Fill in the blanks :
______ are atoms of the same element, which have same number of protons but different mass numbers.