Question:
What is Atomic Number? Who coined this term?
Answer:
The number of protons present inside an atom is equal to its atomic number. It is denoted by symbol Z. Since atom is electrically neutral due to presence of electrons.
Atomic Number (Z) = No. of Protons = Number of Electrons
Mosely (1913) proposed the total positive charge on an atom is equal to its atomic number.
Structure of the Atom
Q 1.
Who discovered protons?
Q 2.
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 3.
Fill in the blanks :
In the three fundamental sub-atomic particles, _________ are negatively charged, _________ are positively charged and ____________ have no charges.
Q 4.
Describe briefly Thomson's model of an atom.
Q 5.
Fill in the blanks :
Anode rays are also called ___________.
Q 6.
Compare an electron, a proton and a neutron in respect of their relative masses and charges.
Q 7.
If an atom contains one electron and one proton, will it carry any charge or not?
Q 8.
What is the relationship between an atom containing 11 protons, 11 electrons and 11 neutrons, and another atom containing 11 protons, 11 electrons and 12 neutrons ?
Q 9.
On the basis of Rutherford’s model of an atom, which subatomic particle is present in the nucleus of an atom?
Q 10.
How many times is a proton heavier than an electron ?
Q 11.
What is the absolute mass and charge of a proton ?
Q 12.
What is the maximum number of electrons which can be accommodated in the L shell of an atom
Q 13.
Write a short note on Nucleus.
Q 14.
What is mass number?
Q 15.
What is ionization energy?
Q 16.
What is the maximum number of electrons an M shell of the atom can accommodate ?
Q 17.
State the number of electrons present in the outermost shell of the atoms of the following elements :
(i) Neon(ii)Chlorine
Q 18.
Give one use each of the following radioactive isotopes :
(a)Uranium-235 (b) Cobalt-60
Q 19.
What is a neutron ? State its relative mass and charge.
Q 20.
Fill in the blanks :
Atoms are made up of __________, ___________ and __________.
Q 21.
Who discovered electrons?
Q 22.
Fill in the blanks :
______ are atoms of the same element, which have same number of protons but different mass numbers.
Q 23.
Fill in the blanks :
Rutherford's scattering experiment is related to to the size of ____________.
Q 24.
If A = 23 and Z = 11 for Na atom, how many protons, electrons and neutrons present in Na atom?
Q 25.
Fill in the blanks :
The maximum number of electrons that can be accommodated in L-shell are _______.
Q 26.
What are ?-particles?
Q 27.
What were the important features of atomic model based on Rutherford's scattering experiment?
Q 28.
Fill in the following blanks in respect of an atom of an element :
No.of
protons | No.of
neutrons | Mass number | Atomic
number | No.of
electrons | Valency |
|---|
| 11 | 12 | ........ | ....... | ........ | ......... |
Q 29.
State the location of electrons, protons and neutrons in an atom.
Q 30.
Name the shell of an atom which can accommodate a maximum of
(a) 2 electrons (b) 18 electrons
Q 31.
How does an electron differ from a neutron ?
Q 32.
Name the radioactive isotope which is used in the treatment of cancer.
Q 33.
What name is given to those atoms which contain the same number of protons and electrons but different number of neutrons ?
Q 34.
What are the properties of anode rays?
Q 35.
Name the scientist who discovered electron.
Q 36.
Which part of an atom was discovered by Rutherford's alpha particle scattering experiment ?
Q 37.
Draw a sketch of Bohr’s model of an atom with three shells.
Q 38.
Fill in the blanks :
The maximum number of electrons that can be accommodated in K-shell are _______.
Q 39.
What is the absolute mass and charge of an electron ?
Q 40.
Fill in the following blanks in respect of an atom of an element:
No.of
protons | No.of
neutrons | Mass number | Atomic
number | No.of
electrons | Symbol |
|---|
| 11 | 12 | ........ | ....... | ........ | ......... |
Q 41.
The total number of electrons in a nitrogen atom is 7. Find the number of valence electrons in it.
Q 42.
What name is given to those isotopes which have unstable nuclei and emit various types of radiations ?
Q 43.
Given that the percentage abundance of the isotope
Ne, is 90% and that of the isotope
Ne, is 10%,calculate the average atomic mass of neon.
Q 44.
Name the fundamental particle not present in the nucleus of hydrogen atom
Q 45.
What are canal rays?
Q 46.
Write the limitations of J.J. Thomson's model of an atom.
Q 47.
Who is known as 'Father of Nucleus Physics'?
Q 48.
Fill in the blanks :
The fundamental sub-atomic particle called neutron was discovered by ___________.
Q 49.
Fill in the blanks :
The _________ of an atom is dense, small in size and is positively charged.
Q 50.
Fill in the blanks :
The total number of protons and neutrons in the nucleus of an atom is called its __________.
