In terms of electronegativity and electrons why does CaO contain an ionic bond?

Calcium oxide is ionic in nature. The Ca-O bond in CaO is formed by the transfer of electron from highly electropositive Ca to the highly electronegative oxygen atom.  The electronegativity difference should be high for the formation of ionic bond.

Explanation:

The ionic compound contains one highly electronegative atom and one highly electropositive atom. The ionic bond is formed by the transfer of electron from the more electropositive atom to electronegative atom.

In calcium oxide , Calcium is alkaline earth metal and it is highly electropositive atom while oxygen is highly electronegative atom. Calcium will transfer its 2 valence electrons to the oxygen atom. The electronegativity difference between calcium and oxygen is greater than 2.0. Hence, the bond in CaO is found to be ionic in nature.

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"