Electronegativity and Bond Type

General Bonds are formed when two atoms share or transfer electrons. As the atoms move closer together, the electrons from each atom are attracted to the protons of another atom.

Bonds Two main types: covalent bonds and ionic bonds Covalent bonds- electrons are shared equally or somewhat shared. Ionic bonds- electrons are completely transferred from one atom to another. This is what causes cations and anions in ionic compounds

Electronegativity How do you determine what bond is formed between two atoms? Look at the electronegativity values of the atoms. Electronegativity-the ability of an atom to attract electrons in a chemical bond.

Electronegativity Atoms with higher electronegativity attract electrons more strongly. If atoms form a bond, the electrons are held close. If the electronegativity difference is large enough, electrons can be pulled away from the other atom.

Electronegativity Each atom has an electronegativity value. Elements that have low values lose electrons easily. Elements that have high values gain electrons easily.

Bond Types Little or no difference in electronegativity allows for a covalent bond. Ex: H2, both atoms have an electronegativity of 2.1 2.1-2.1 = 0 (no difference in electronegativity)

Bond Type When the electronegativity difference is large, electrons are not shared equally. The bond is ionic.

Bond Types Nonpolar covalent bonds = 0.0-0.39 Ionic bonds = 1.7 or higher

Predicting Bond Types To predict the bond type for two atoms, find the electronegativity value for each element Subtract the smaller value from the larger.

Examples Predict the bond type in: HCl NaCl CCl4 NH3