Download Covalent Bonds

Covalent Bonds 1. Electronegativity Difference • The elements have similar electronegativity values (both high) • Both atoms will be nonmetals • Ex. CO or H2O 2. Bond Formation • Both atoms have very high ionization energies so neither atom will be able to take valence electrons completely off the other…they will share them • Because no electrons are transferred, there are no ions in covalent bonds •
Molecules can be nonpolar if electrons are evenly shared within the molecule •
Molecules can be polar if electrons are unevenly shared within the molecule - The more electronegative atom will be partially negative - The less electronegative atom will be partially positive 3. Covalent compounds are called molecules 4. Properties of Covalent Compounds • When solid/liquid, covalent compounds do not conduct electricity because they do not contain ions (no charges) • Only polar covalent molecules can dissolve in water (“like dissolves like”) • When dissolved, covalent compounds do not ionize so they cannot conduct electricity (movement but still no ions) • The covalent bond is generally not as strong as the ionic bond • Covalent compounds tend to have very low melting and boiling points • At room temperature, this makes most covalent compounds gas or liquid