Section 2

Covalent Bond

Formed when two atoms share one or more pairs of valence electrons

Ionic Bond

• Formed when one atom completely transfers electron(s) to another, creating oppositely charged ions that attract each other.

Why do ions have positive charge

An atom becomes a cation when it loses electrons (fewer negative charges than protons

Why do atoms have negative charge

An atom becomes an anion when it gains electrons (more negative charges than protons

What is electronegativity? What does it determine in a covalent bond?

an atom's affinity or attraction for shared electrons in a bond. It determines whether a covalent bond is non-polar (equal sharing) or polar (unequal sharing).

What makes a molecule polar?

Significant differences in electronegativity cause electrons to spend more time around one atom, creating partial positive ($\delta+$) and partial negative ($\delta-$) poles

Non-polar

• Electrons are shared equally (similar electronegativities), or symmetrical structural arrangement cancels out individual bond dipoles.