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
A table showing the systematic arrangement of elements is called a periodic table.
The horizontal rows of the periodic table are called periods.
Elements that have similar properties lie in the same column in the periodic table.
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.
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.
Properties of the element are the periodic function of their atomic masses.
i. His failure to explain the position of isotopes.
ii. There was wrong order of the atomic masses of some elements.
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.
Those elements which belong to the d and f blocks are called transition elements.
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.
Half of the distance between the nuclei of the two bonded atoms is called the atomic radius.
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.
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.
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.
The ability of an atom to attract the shared pair of electrons towards itself in molecules is called electronegativity.
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.
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.
First, three periods are considered normal periods.
Depending upon outermost electrons and electronic configuration elements in the periodic table are arranged in groups.
Because when we move from left to right in a period atomic size of the atom decreases.
Electron affinity increases because of a decrease in the atomic size of the atom from left to right in a period.
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.
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).
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.
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.
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.