Chemistry
Fill in the blanks from the words A to F given below.
A: Decreases B: Increases C: Remains same D: Increases by one E: Electropositive F: Electronegative
- Across a period from left to right in the Modern Periodic Table.
No. of electron shells …………… ; No. of valence electrons ……………; Electronegativity ……………; Character of elements changes from …………… to …………… - Down a group in the Modern Periodic Table.
No. of electron shells ……………; No. of valence electrons ……………; Electronegativity ……………; Character of elements changes from …………… to ……………
Answer
- Across a period from left to right in the Modern Periodic Table.
No. of electron shells remains same; No. of valence electrons increases by one; Electronegativity increases; Character of elements changes from electropositive to electronegative. - Down a group in the Modern Periodic Table.
No. of electron shells increases by one; No. of valence electrons remains same; Electronegativity decreases; Character of elements changes from electronegative to electropositive.
Related Questions
Name or state the following with reference to the elements of the first three periods of the periodic table.
(a) The noble gas having duplet arrangement of electrons.
(b) The noble gas having an electronic configuration 2, 8, 8.
(c) A metalloid in period 2 and in period 3.
(d) The number of electron shells in elements of period 1, period 2 and period 3.
(e) The valency of elements in group 1 [IA].
(f) The group whose elements have zero valency.
(g) An alkaline earth metal in period 3.
(h) The non-metallic element present in period 3 other than sulphur and chlorine.
(i) A non-metal in period 2 having electronic configuration 2, 6.
(j) An electrovalent compound formed between an alkali metal and a halogen.
(k) A covalent compound formed between an element in period 1 and a halogen.
(l) An alkali metal in period 3 which dissolves in water giving a strong alkali.
(m) A metal in period 3 having valency 3.
(n) The bridge elements of period 3 of group 1 [IA], 2 [IIA] and 13 [IIIA].
(o) The periods which contain the inner transition elements.
(p) The formula of the hydroxide of the element having electronic configuration 2, 8, 2.
(q) The valency of the element in period 3 having atomic number 17.
(r) A non-metal in period 2 which is tetravalent.
Select the correct answer from the words in bracket.
- He arranged elements in increasing order of atomic numbers. [Dobereiner/ Moseley / Mendeleeff
- Is a metal in period 2 having electronic configuration 2, 1. [Beryllium / Lithium / Sodium]
- Is a period having elements from atomic no. 11 to 18. [period – 1/2/3]
- The most reactive halogen from group 17. [chlorine/fluorine/bromine]
- Is the group number of the element whose atomic number is 4. [group - 1/group – 2/group – 18]
Give reasons for the following.
Mendeleeff's contributions to the periodic table, laid the foundation for the Modern Periodic Table.
Give reasons for the following.
Properties of elements are periodic functions of their atomic numbers and not atomic weights.