coordinate covalent
coordinate covalent bonds<br>
coordinate covalent
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Presentation Transcript
Aim: What are coordinate covalent bonds? DO NOW: FINISH THE WORKSHEET FROM YESTERDAY. IF YOU HAVE FINISHED WALK AROUND AND HELP OTHERS.
Coordinate Covalent Bonds • A coordinate bond (also called a dative covalent bond) is a covalent bond (a shared pair of electrons) in which both electrons come from the same atom. • A coordinate covalent bond is usually shown with an arrow.
C O Coordinate Covalent Bond • When one atom donates both electrons in a covalent bond. • Carbon monoxide • CO
Coordinate Covalent Bond • When one atom donates both electrons in a covalent bond. • Carbon monoxide • CO C O
Coordinate Covalent Bond • When one atom donates both electrons in a covalent bond. • Carbon monoxide • CO C O
General Rules • Select the central atom (atom in the middle); the least electronegative atom (H and halogens will not be central atoms) • Count the total number of valence electrons there should be. • Put one bond between each atom. Put the rest of the valence electrons on the outer atoms. • Check if every atom fulfills octet. If not move paired electrons to fulfill octet. • Recount the number of total shared valence electrons.
Example 2 • N2O
Polyatomic Ions • A polyatomic ion is a tightly bound group of atoms that has a positive or negative charge and behave as a unit. • A group of atoms that are covalently bound and as a whole have a charge.
Which compound contains both ionic and covalent bonds? • HBr • CBr4 • NaBr • NaOH
Practice 1. Draw the electron dot structure for the polyatomic boron tetrafluoride anion (BF4-)
Practice 2. Draw the electron dot structure for the hydrogen carbonate ion (HCO3-). Carbon is the central atom, and hydrogen is attached to oxygen in this polyatomic anion.
Exceptions to Octet Rule • The octet rule cannot be satisfied whose total number of valence electrons is an odd number. There are also molecules in which an atom has fewer, or more, than a complete octet in the valence electrons.
Example 1 • Boron has a tendency to form compounds in which it has an incomplete octet. For example BF3
Example 2 • Atoms of elements in the third or higher periods can exceed their octet as they have d orbitals available for bonding. For example SF6
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