Electronegativity

Definition

Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. It plays a crucial role in determining how atoms bond together and the nature of their bonds, influencing properties such as molecular geometry and polarity. The concept is essential in understanding how elements interact within the periodic table and how these interactions shape the characteristics of molecules.

5 Must Know Facts For Your Next Test

1. Electronegativity increases across a period from left to right due to increasing nuclear charge, which attracts electrons more strongly.
2. Electronegativity decreases down a group because the increased distance from the nucleus makes it harder for the atom to attract bonding electrons.
3. The Pauling scale is commonly used to quantify electronegativity, with fluorine being the most electronegative element assigned a value of 4.0.
4. In ionic bonding, a significant difference in electronegativity between two atoms leads to the complete transfer of electrons from one atom to another.
5. Electronegativity differences between atoms can determine whether a bond is nonpolar covalent, polar covalent, or ionic.

Review Questions

• How does electronegativity influence the type of bond formed between two atoms?
  • Electronegativity plays a key role in determining whether a bond will be ionic, polar covalent, or nonpolar covalent. When two atoms have similar electronegativity values, they tend to share electrons equally, forming a nonpolar covalent bond. If there is a significant difference in electronegativity, one atom will attract the bonding electrons more strongly, leading to an ionic bond or a polar covalent bond, depending on the degree of difference.
• Analyze how trends in electronegativity across periods and groups relate to atomic structure.
  • Trends in electronegativity are closely linked to atomic structure. As you move across a period from left to right, electronegativity increases because atoms have more protons in their nucleus, enhancing their ability to attract electrons. Conversely, as you move down a group, electronegativity decreases due to increased distance between the nucleus and outer electrons, which makes it harder for the atom to attract additional electrons. This atomic structure affects bonding behavior and chemical reactivity.
• Evaluate the impact of electronegativity on molecular geometry and polarity, providing examples.
  • Electronegativity directly influences molecular geometry and polarity by affecting how electrons are distributed in bonds. For example, in water (H₂O), oxygen's higher electronegativity creates polar bonds with hydrogen, resulting in a bent molecular geometry and making water a polar molecule. In contrast, carbon dioxide (CO₂) has polar bonds between carbon and oxygen, but its linear shape causes the dipoles to cancel out, making CO₂ nonpolar. Thus, differences in electronegativity can lead to diverse molecular properties.

Related terms

Ionization Energy: The energy required to remove an electron from an atom or ion, which is related to how strongly an atom can hold onto its electrons.

Covalent Bond: A type of chemical bond that involves the sharing of electron pairs between atoms, often influenced by their electronegativity values.

Polar Molecule: A molecule that has a net dipole moment due to the presence of polar bonds, often resulting from differences in electronegativity between the bonded atoms.