Summary
Highlights
Ionic bonding involves the transfer of electrons from one element to another, typically forming ions. An example is the reaction between sodium and chlorine. Sodium, a metal, has one valence electron and tends to give it away, forming a positive ion. Chlorine, a non-metal, has seven valence electrons and tends to receive an electron, forming a negative ion. The electrostatic attraction between these oppositely charged ions creates the ionic bond.
Covalent bonding involves the sharing of electrons between atoms. Hydrogen is used as an example; each hydrogen atom needs one more electron to fill its first shell, so they share electrons to form a bond. A single bond represents the sharing of two electrons.
There are two types of covalent bonds: polar and non-polar. A non-polar covalent bond occurs when electrons are shared equally, as seen between two hydrogen atoms. A polar covalent bond occurs when electrons are shared unequally due to differences in electronegativity. For instance, in hydrogen fluoride, fluorine is more electronegative than hydrogen, pulling the shared electrons closer to itself, creating partial negative and positive charges (a dipole).
Electronegativity is an atom's ability to attract electrons. A polar covalent bond results from unequal sharing of electrons due to significant electronegativity differences. Generally, if the electronegativity difference is 0.5 or greater, the bond is considered polar covalent; otherwise, it's non-polar covalent.
The video provides practice problems to classify bonds as ionic, polar covalent, or non-polar covalent. Examples include magnesium oxide (ionic due to metal and non-metal), two chlorine atoms (non-polar covalent as they are identical non-metals), sodium fluoride (ionic due to metal and non-metal), and HBr (polar covalent based on electronegativity difference). Carbon-hydrogen bonds are typically non-polar, and hydrogen-oxygen bonds are highly polar.