Bonding and Electronegativity (Lecture Notes)

Flashcards covering covalent bonds, polar vs nonpolar covalent bonds, ionic bonds, metallic bonding, and electronegativity concepts from the notes.

What is the defining feature of a covalent bond?

Two nonmetals share electrons to fill their valence shells, forming a shared electron pair (a covalent bond, often shown as a line in Lewis structures).

What does a line between two atoms in a Lewis structure represent?

A covalent bond; a single line for a single bond, two lines for a double bond, and three lines for a triple bond.

What is a nonpolar covalent bond?

A covalent bond in which electrons are shared almost equally because the atoms have similar electronegativities (difference typically < 0.5).

What is a polar covalent bond?

A covalent bond in which electrons are shared unequally due to a larger electronegativity difference (difference ≥ ~0.5), creating partial charges on the atoms.

If boron has EN ~2.0 and chlorine EN ~3.0, is the B–Cl bond polar or nonpolar?

Polar covalent, since the EN difference is 1.0 (greater than 0.5) and chlorine hogs electrons more.

Is a carbon–hydrogen bond typically polar or nonpolar? Why?

Nonpolar covalent; carbon (2.5) and hydrogen (2.1) differ by about 0.4, leading to fairly even sharing (not perfectly but mostly).

What defines an ionic bond?

A bond formed between a metal and a nonmetal with transfer of electrons, resulting in ions (example: sodium and bromine).

What is metallic bonding?

In metals, electrons are delocalized and move freely among fixed nuclei, forming a 'sea of electrons' that enables electrical conductivity.

Why do metals conduct electricity well?

Because their valence electrons are delocalized and can move freely through the metal lattice.

How do electronegativity differences help classify bonds?

If the difference is < ~0.5, the bond is nonpolar covalent; if ≥ ~0.5, the bond is polar covalent (the more electronegative atom gains a partial negative charge).

What happens when two nonmetals share electrons unevenly in a bond?

The bond is polar covalent, with the more electronegative atom carrying a partial negative charge and the other a partial positive charge.

What are the main bond types discussed in the notes?

Covalent bonds (including nonpolar and polar covalent), ionic bonds, and metallic bonds, along with the concept of electronegativity to predict polarity.