(a) Electropositive nature of the element(s) increases down the group and decreases across the period (b) Electronegativity of the element decreases down the group and increases across the period (c) Atomic size increases down the group and decreases across a period (left to right) (d) Metallic character increases down the group and decreases across a period. Based on the above trends of the Periodic Table, answer the following about the elements with atomic numbers 3 to 9. (a) Name the most electropositive element among them (b) Name the most electronegative element (c) Name the element with the smallest atomic size (d) Name the element which is a metalloid (e) Name the element which shows maximum valency.

Answer:

Mendeleev’s periodic table is an arrangement of elements in an increasing atomic mass order in a tablet form, such that it reflects similarities and trends in the behaviour of elements. Mendeleev’s periodic table can be understood better by reversing the arrangement of the elements.

  • Here elements are, arranged in an increasing order atomic mass, in a horizontal line.
  • This horizontal arrangement of elements is a ‘period’.
  • When an element has high similarity to an earlier element, the new element is, placed just below the earlier element having similar properties to start a new period.
  • The period’s one below the other form a ‘column’ (group). Thus, Mendeleev’s periodic table consists of horizontal rows and vertical columns or periods and groups, respectively.
  • If the element is similar but not very much, it is, placed below but slightly away to differentiate it. Each column will have two sub-columns (A and B) such that elements in the same sub-columns show more resemblance.

(a) Eka-Silicon was replaced by germanium, Eka-aluminium was replaced by Gallium

(b)

  • Germanium (Ge) – Group 14, Period 4
  • Gallium(Ga) – Group 13, Period 4

(c) Germanium is a metalloid and Gallium is a metal.

(d) Germanium(Ge) has 4 electrons, Gallium(Ga) has 3 valence electrons.

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