An element X (atomic number 17) reacts with an element Y (atomic number 20) to form a compound. (i) Write the position of these elements in the modern periodic table. (ii) Write the formula of the compound formed. Justify your answer in each case.

An element X (atomic number 17) reacts with an element Y (atomic numbe

1.	An element X (atomic number 17) reacts with an element Y (atomic number 20) to form a compound. (i) Write the position of these elements in the modern periodic table. (ii) Write the formula of the compound formed. Justify your answer in each case.
Answer» Solution :(i) The position of elements X in the modern periodic table is group number 17 and PERIOD number 3. The position of element Y in the modern periodic table is group number 2 and period number 4. Electronic configuration of element X = 2, 8,7. It has 3 shells so period number 3. Halogens are kept in group 17. Electronic configuration of element Y = 2, 8, 8,2 It has 4 shells so period number is 4. The VALENCE shell has 2 electrons so the group number is 2. (ii) Formula of the compound : `{:("Valency of element Y","Valency of element X"),("2","1"):}` `thereforeYX_(2)`