Chapter 03 Metals And Non-metals Questions-03
Questions
1. (i) Write the electron-dot structures for sodium, oxygen and magnesium.
(ii) Show the formation of $Na_2 O$ and $MgO$ by the transfer of electrons.
(iii) What are the ions present in these compounds?
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Answer
(i) The representation of elements with valence electrons as dots around the elements is referred to as electron-dot structure for elements.
(a) $Sodium(2,8,1)=\dot{Na}$
(b) Oxygen $(2,6)=\ddot{:}:$ :
(c) Magnesium $(2,8,2)=\ddot{M}$
(ii)
(iii) The ions present in $Na 2 O$ are $Na+$ and $O 2-$ ions and in $MgO$ are $Mg 2+$ and $O 2-$ ions.
2. Why do ionic compounds have high melting points?
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Answer
(i) Mineral: Most of the elements occur in nature as in combined state as minerals. The chemical composition of minerals is fixed.
(ii) Ore: Minerals from which metals can be extracted profitably are known as ores.
(iii) Gangue: The impurities (sand, silt, soil, gravel, etc.) present in the ore are called gangue.
