In a molecule of calcium sulfide, calcium has two valence electron bonds, and a sulfur atom has six valence electrons. How many lone pairs of electrons are present in the Lewis structure of calcium sulfide? Also, state why. A. one
B. two
C. three
D. four
E. none

There are 2 lone pairs

Given

a molecule of calcium sulfide

two valence electron of Calcium(Ca)

six valence electrons of Sulfur(S)

Required

number of lone pairs of electrons

Solution

Lewis structure shows the form of bonds that occur in the valence electrons of an element or compound

Valence electrons are electrons used in a chemical bond

To achieve stability, the element S needs 2 more electrons which are obtained from 2 electrons from the Ca element,

A lone pair electrons means refers to an unshared pair of electrons(not bonding to the other 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"