Determine whether each compound is ionic or covalent and write the appropriate Lewis structure.
In chemical bonds, atoms can either transfer or share their valence electrons. In the extreme case where one or more atoms lose electrons and other atoms gain them in order to produce a noble gas electron configuration, the bond is called an ionic bond.
Typical of ionic bonds are those in the alkali halides such as sodium chloride, NaCl.
For the HCN Lewis structure, calculate the total number of valence electrons for the HCN molecule. After determining how many valence electrons there are in HCN, place them around the central atom to complete the octets. ... Note: Hydrogen (H) atoms always go on the outside of a Lewis structure.
For the ClF Lewis structure, calculate the total number of valence electrons for the ClF molecule. After determining how many valence electrons there are in ClF, place them around the central atom to complete the octets.
Iodine needs 7 electrons and Magnesium needs 2 (because of their group number in the periodic table) and there are 2 Iodines so the total amount is 14. You get 8 from the two double bonds and then fill in Iodine's octet until you reach 14. Iodine does not have to have a full octet because it's below the 3rd period and those elements often bend the octet rules.
:I = Mg = I:
Ca has two electrons around it and S has 6 electrons around it. S is very electronegative so it will take both electrons from Ca.
Thus, the lewis dot structure will be S with 6 electrons around it, single bonded to Ca. From this, we can assume that Ca donates both electrons to bond with S. This makes sense since S has achieved octet.