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How do covalent bonds differ from ionic bonds?
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covalent bond
In polar covalent bonds, such as that between hydrogen and oxygen atoms, the electrons are not transferred from one atom to the other as they are in an ionic bond. Instead, some outer electrons merely spend more time in the vicinity of the other atom. The effect of this orbital distortion is to induce regional net charges that hold the atoms together, such as in water molecules.
Covalent and ionic bonds differ primarily in how atoms interact with their valence electrons to achieve stability.12
- Covalent Bonds: These form when atoms share pairs of electrons. This sharing typically occurs between atoms with similar electronegativities. Covalently bonded atoms often form discrete molecules, such as hydrogen gas ().321
- Ionic Bonds: These result from the permanent transfer of one or more electrons from one atom to another, creating oppositely charged ions (cations and anions). The bond itself is the electrostatic attraction between these charged species. Ionic bonds usually form between elements with a large difference in electronegativity, such as metals and nonmetals.124
While these are distinct categories, they exist on a spectrum; an ionic bond can be viewed as the extreme case of a polar covalent bond where the sharing of electrons is so unequal that it effectively becomes a complete transfer. Furthermore, substances formed by these bonds behave differently: ionic compounds often form crystalline solids that conduct electricity when dissolved, whereas many covalent compounds do not.125