Covalent Bonding in Ions
Charges indicate that there are more or fewer electrons than normal. For instance, the negative charge on SO42- means that there are two extra electrons to use when bonding. Conversely, the positive charge on NH4+ means that there is one less electron to use when bonding.
ex. NO3-
Tips:
- Typically, the single element is surrounded by the others (in this case, N will be in the middle and the Os will “click into” the central N.
- Since both N and O are both non-metals, we expect the bonding to be some form of covalent, so the atoms will share electrons.
- Since nitrate has a -1 charge, there will be one extra electron (represented by the triangle) available to use in the bonding.
- Be sure all atoms have satisfied the Octet Rule and have a full outer shell (usually eight electrons).
- Trial and error is your best bet if you don’t immediately see the answer. See my thought process below.
- Always check to ensure the Octet Rule is satisfied and that you have included charges and a bracket where appropriate.
Covalent Bonding in Ionic Compounds
Ionic compounds that contain polyatomic ions will have both ionic and covalent bonding present.
ex. KIO3
Tips
- First survey the elements – both I and O are non-metals and will bond covalently by sharing electrons. The K is a metal and will bond to the iodate group using ionic bonding via electron transfer.
- Always start with the covalent bonding. Use what you already know – place the I in the middle and click in the Os around it.
- Then transfer the electron from K to one of the Os. Never transfer an electron to a central atom – IRL the electron would be blocked from the I by the Os.
- Always check to ensure the Octet Rule is satisfied and that you have included charges and a bracket where appropriate.
To convert to a structural diagram,
write down the element symbols in the same relative positions as in the Lewis
diagram. Replace all shared electron
pairs with a dashed line and remove any other electrons
Homework: LDD&SD # 3, 5
