FBISE 9th Class Chemistry Chapter 3 Periodic Table and Periodicity of P Short Questions Answers

FBISE 9th class Chemistry Chapter 3 Periodic Table and Periodicity of P Short Questions with answers are combined for all 9th class(Matric/ssc) Level students. Here You can prepare all Chemistry Chapter 3 Periodic Table and Periodicity of P short question in unique way and also attempt quiz related to this chapter. Just Click on Short Question and below Answer automatically shown. After each question you can give like/dislike to tell other students how its useful for each.

Class/Subject: 9th Class Chemistry

Chapter Name: Periodic Table and Periodicity of P

Board: Federal  Board

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FBISE 9th Class Chemistry Chapter 3 Periodic Table and Periodicity of P Short Questions Answers

Define Periodic table?

A table showing the systematic arrangement of elements is called a periodic table.

Define Periods?

The horizontal rows of the periodic table are called periods.

What do you mean by group or family in the periodic table?

Elements that have similar properties lie in the same column in the periodic table.

Define Doberiener traids.

A German chemist Doberiener observed the relationship between atomic masses of several groups of three elements called triads. In these groups, the central or middle elements had an atomic mass average of the other two elements.

Describe Newland of Octaves.

In 1864 British chemist Newlands put forward his observation in the form of the law of octaves. He noted that there was a repetition in the chemical properties of every eight elements if they were arranged by the increasing atomic masses.

Describe Mendeleev’s periodic law.

Properties of the element are the periodic function of their atomic masses.

Write down the drawbacks of Mendeleev’s periodic table.

i. His failure to explain the position of isotopes.
ii. There was wrong order of the atomic masses of some elements.

Define group number and period number?

Group number: It tells about the number of electrons present in the outermost shell of an atom.
Period number: It tells about the number of electronic shells present in the atoms.

Define transition elements?

Those elements which belong to the d and f blocks are called transition elements.

What do you mean by period function?

Period function means properties of elements repeating after regular intervals such that elements of similar properties and similar configuration are placed in the same group.

Define Atomic radius?

Half of the distance between the nuclei of the two bonded atoms is called the atomic radius.

Define ionization energy. Write down its unit.

The ionization energy is the amount of energy required to remove the most loosely bounded electron from the valence shell of an isolated gaseous atom. Its unit is kJmol-1.

Define electron affinity. Write down its unit.

The amount of energy released when an electron is added up in the outermost shell of an isolated gaseous atom. Its unit is kJmol-1.

What is the shielding effect?

The decrease in the attractive force exerted by the nucleus on the valance shell electrons due to the presence of the electrons lying between the nucleus and the valance shell is called the shielding effect.

Define electronegativity.

The ability of an atom to attract the shared pair of electrons towards itself in molecules is called electronegativity.

What is meant by the periodicity of properties?

The electronic configuration of the elements shows a periodic variation with the increasing atomic number. Therefore, the elements also show periodic variation in their physical and chemical properties. Elements having similar valence shell electronic configuration have been placed in the same group one below the other.

Why noble gases are not reactive?

Noble gases are not reactive because they have their valence shells filled. They have 2 or 8 electrons in their valence shells. Their atoms do not have vacant spaces in their valence shell to accommodate more electrons. Therefore they do not gain, lose or share electrons.

How many periods are considered to be normal periods?

First, three periods are considered normal periods.

What is the reason for arranging elements in the group?

Depending upon outermost electrons and electronic configuration elements in the periodic table are arranged in groups.

Why is ionization energy increasing in a period?

Because when we move from left to right in a period atomic size of the atom decreases.

Why electron affinity increase in a period?

Electron affinity increases because of a decrease in the atomic size of the atom from left to right in a period.

Why the ionization energy of sodium is less than that of magnesium?

Because both sodium and magnesium belong to the same period when we move left to right in the period atomic size decreases and ionization energy increases that is why sodium has low ionization energy because of greater size than magnesium.

How does the shielding effect decrease the forces of electrostatic attractions between the nucleus and outermost electrons?

The electron present between the nucleus and the outermost shell of an atom reduces the nuclear charge felt by the electrons present in the outermost shell. The attraction of outer electrons towards the nucleus is partially reduced because of the presence of inner electrons. As a result, an atom experiences less nuclear charge than that of the actual charge which is called Effective nuclear charge (Zeff).

Why cesium atomic no.55 requires little energy to release its one electron present in the outermost shell?

Cesium requires little energy to release its outermost electrons because it has a greater atomic size and low ionization energy so the cesium atom distance between the nucleus and the outermost shell is very large.

Why and how elements are arranged in the 4th period?

The elements are arranged in the 4th period because they are all having the same electronic shells and elements are arranged in the 4th period by increasing atomic number from left to right in a period.

What is the difference between Mendeleev’s periodic law and Modern periodic law?

Mendeleev’s periodic law: Properties of elements are the periodic functions of their atomic masses.
Modern periodic law: Properties of the element are the periodic functions of their atomic number.

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