Periodic Classification of Elements

Temperature dependence of resistivity ρ(T) of semiconductors, insulators, and metals is significantly based on the following factors:
a) number of charge carriers can change with temperature T
b) time interval between two successive collisions can depend on T
c) length of material can be a function of T
d) mass of carriers is a function of T

The correct answer is a) number of charge carriers can change with temperature T b) time interval between two successive collisions can depend on T

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An element X belongs to group 2 and another element Y belongs to group 15 of the periodic table: (a) What is the number of valence electrons in X? (b) What is the valency of X? (c) What the number of valence electrons in Y? (d) What is the valency of Y? Explain how you have arrived at your answers.

(a) 2. For the group 1 and 2, the number of valence electrons is equal to the group number and in the 2nd group, it is equal to 2. (b) 2. Valency is determined by the number of valence electrons...

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Fill in the blanks in the following statements: (a) The horizontal rows in a periodic table are called _______. (b) In going across a period (right to left) in periodic table, the atomic size of the atom _______. (c) On moving from right to left in the second period, the number of valence electrons _______. (d) On going down in a group in the periodic table, the metallic character of elements _______. (e) The tendency to gain an electron_______ on moving down in a group of the periodic table.

(a) Periods (b) Increases (c) Decreases (d) Increases (e) Decreases

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Nitrogen (atomic number 7) and phosphorus (atomic number 15) belong to group 15 of the Periodic Table. Write the electronic configuration of these two elements. Which of these will be more electronegative? Why?

Nitrogen: Atomic number - 7 Electronic configuration - 1s2 2s2 2p3 Nitrogen: Atomic number - 15 Electronic configuration - 1s2 2s2 2p6 3s2 3p3 The number of shell increases in the periodic table...

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An atom has electronic configuration 2, 8, 7. (a) What is the atomic number of this element? (b) To which of the following elements would it be chemically similar? (Atomic numbers are given in parentheses.) N(7), F(9), P(15), Ar(18)

(a)The element is Chlorine (Cl) and the atomic number of chlorine is 17. (b) The atom with the electronic configuration of 2, 8, 7 which is the chlorine is chemically identical to Fluorine (F) which...

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Which element has? (a) Two shells, both of which are completely filled with electrons? (b) The electronic configuration 2, 8, 2? (c) A total of three shells, with four electrons in its valence shell? (d) A total of two shells, with three electrons in its valence shell?(e) twice as many electrons in its second shell as in its first shell?

(a) Neon (Ne) has two shells in which both are completely filled with electrons. (b) Magnesium (Mg) has the electronic configuration 2, 8, 2. (c) Silicon (Si) has a total of three shells, with four...

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Which of the following statements is not a correct statement about the trends when going from left to right across the periods of Periodic Table. (a) The elements become less metallic in nature. (b) The number of valence electrons increases. (c) The atoms lose their electrons more easily. (d) The oxides become more acidic

Correct Answer: (c) The atoms lose their electrons more easily Explanation: Atoms do not lose their electrons easily because as we move from left to right across the periodic table, the non-metallic...

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(a) Lithium, sodium, potassium are all metals that react with water to liberate hydrogen gas. Is there any similarity in the atoms of these elements? (b) Helium is an unreactive gas and neon is a gas of extremely low reactivity. What, if anything, do their atoms have in common?

(a) Lithium, sodium, potassium are the metals that are unstable because of the unfilled outermost shells. This is the reason that they react with water in order to release hydrogen and these metals...

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Which of the following statement is correct in regard to the classification of elements ? (a) Elements in the periodic table are arranged on the basis of increasing atomic masses (b) Elements in Mendeleev’s periodic table are arranged on the basis of increasing atomic numbers (c) In modern periodic table, the element nickel of lower atomic mass is kept before the element cobalt of higher atomic mass (d) In modern periodic table, the isotopes of chlorine having different atomic masses are kept in the same group.

Option (d) is the answer.

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(a) How could the modern periodic law remove various anomalies of Mendeleev’s periodic table? Explain with examples. (b) Is it possible to have an element having atomic number 1.5 placed between hydrogen and helium?

(a) Anomalies of Mendeleev’s periodic table: 1. Elements are arranged in increasing order of atomic number in modern periodic table, thus there was no need for keeping more than one element in one...

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(a) State any three limitations of Mendeleev’s classification of elements. (b) Besides gallium, which two other elements have since been discovered for which Mendeleev had left gaps in his periodic table ? (c) Which group of elements was missing from Mendeleev’s original periodic table?

(a) Limitations of Mendeleev’s classification of elements: (i) It failed to explain the position of isotopes. (ii) The wrong order of atomic masses of some elements could not be explained. (iii) The...

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(a) How do the properties of eka – aluminium element predicted by Mendeleev compare with the actual properties of gallium element? Explain your answer. (b) What names were given by Mendeleev to the then undiscovered elements (i) scandium (ii) gallium, and (iii) germanium?

(a) Eka-aluminium and gallium are the two different names for a single element. Eka-aluminium has same property like density, melting point etc as gallium element and it was proposed before the...

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State whether the following statement are true or false: (a) Newlands divided the elements into horizontal rows of eight element each. (b) According to Mendeleev’s periodic law, the properties of elements are a periodic function of their atomic numbers.

(a) False. Newlands divided the elements into horizontal rows of seven element each and the first and last elements ended up on the same note. (b) False. According to Mendeleev’s periodic law, the...

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Which of the following statements about the Modern Periodic Table is correct:
(a) It has 18 horizontal rows known as Periods
(b) It has 7 vertical columns known as Periods
(c) It has 18 vertical columns known as Groups
(d) It has 7 horizontal rows known as Groups

Solution: The answer is (c) It has 18 vertical columns known as Groups Explanation: The modern periodic table is divided into 18 groups and seven periods. Columns are referred to as groups, while...

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