Electronegativity and Bonding

1. Electronegativity and Bonding

2. Two types of bonds • Ionic bonds: electrons completely transferred from one atom to another. Compound is held together by electrical attraction. • Covalent bond: electrons are shared between two atoms.

3. Sharing • Within a covalent bond, electrons are not always shared evenly. • Nonpolar covalent bond-equal sharing • Polar covalent bond-unequal sharing

4. Electronegativity and Bonding • Electronegativity (EN) is a measure of an atom’s ability to attract electrons away from other atoms. • Atoms with high electronegativity values (EN’s) are the best electron attractors and atoms with low electronegativity values (EN’s) are the worst electron attractors. • The electronegativityscale is a relative(arbitrary) scale based on the element fluorine, because fluorine is the best of the best electron attractors

5. Electronegativity and Bonding • NOTICE: Most noble gases do not have EN values assigned because they do not attract electrons.

6. Electronegativity differences • Type of bond can be determined using the difference in two element’s electronegativities • Ionic=greater than 1.8 • Polar covalent= 0.5-1.8 • Nonpolar covalent= less than 0.5

7. Examples • HF • CH4 • NaCl