i) Write the electron-dot structures for sodium (11), oxygen (8), chlorine (17) and magnesium (12). Show the formation of Na20 and MgO by the transfer of electrons.
(ii) Name the ions present in these compounds.
CBSE Class X Science LA (5 Marks)
Answers
i) Na O Cl Mg
2.8.1 2.6 2.8.7 2.8.2
Electron dot structure of sodium(11),oxygen(8)chloride(17)and magnesium(12) are as follow and formula of Na20 andMgO is written as follow:---
i) Electron dot structure of elements represent the distribution of electrons of elements in its various electronic shell.
1)For sodium (11) electronic configuration is 2,8,1
2)For oxygen with 8 electrons we have 2,6
3)For chlorine with 17 electrons distribution is 2,8,7
4) For magnesium with 12 electrons we have 2,8,2.
â—†Formation of Na2O by electron transfer since sodium has 1 electron in outer shell so can donate this electron to get stable configuration hence valency is +1 and for oxygen which is 2 electron short for stable configuration hence its valency is -2 so by criss cross formula is Na2O.
â—†similarly for Mg2O with magnesium with 2 electron to donate valency is +2and oxygen valency is -2 by criss cross formula is MgO.
ii) Ions in the formation of Na2O and MgO are Na^+,O^2- and Mg^2+
