1Which one of these nonmetals is the most reactive: fluorine, chlorine, bromine or iodine?
2Which one of these metals is the most reactive: lithium, sodium, potassium or cesium?
3Which one represents the correct order of increase in chemical reactivity of metals: Be < Mg < Ca, Na < Li < K, Mg < Al < Si, or C < O < N?
4Give reason: The size of atoms increases on going from top to bottom in a group of the periodic table.
5Give reason: The size of atoms decreases on going from left to right of a period in the periodic table.
6Give reason: Potassium is more reactive than sodium.
7Give reason: Fluorine is more reactive than chlorine.
8Give reason: The metallic characters of elements decrease and nonmetallic characters increase on going from left to right of a period in the modern periodic table.
9Give reason: In the part of the periodic table that reads Li, Be, B, C, N, O, F and Ne from group IA to group VIIIA, the atomic size decreases from Li to Ne.
10Write the differences between chlorine and sodium.
11Write the differences between the elements of group IA and group VIIA.
12Write the differences between electronegativity and electropositivity.
13In which group do fluorine, chlorine and bromine lie in the periodic table? Which one is more reactive among them?
14Nitrogen has five valence electrons. Why is its valency 3 and not 5?
15Argon is the smallest atom of the third period. Why is chlorine, and not argon, the most electronegative element of that period?
16How does valency change as we move across a period and down a group?
17Arrange oxygen, sulphur and selenium in decreasing order of chemical reactivity, and explain the order.