Based on this zoomed-in view of Example 4, I can clearly see the process for Hydrogen Chloride (HCl).
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Initial State: A hydrogen atom (labeled "H") with one electron shell containing 1 electron is shown approaching a chlorine atom (labeled "Cl") with three electron shells and 7 valence electrons in its outermost shell.
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Bond Formation: A red curved arrow points from the hydrogen atom to the chlorine atom, indicating that each atom contributes one electron to form a shared pair.
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Final State: The hydrogen and chlorine atoms are now bonded together with a single covalent bond, represented by a pair of blue dots between the nuclei. This sharing gives the hydrogen atom access to 2 electrons (a full first shell) and the chlorine atom access to 8 electrons in its valence shell, achieving stability for both.
This is an example of a single covalent bond. However, unlike the previous examples, this bond is
polar. This is because chlorine is much more electronegative than hydrogen. As a result, the shared electrons are pulled closer to the chlorine atom, giving it a partial negative charge (δ-) and leaving the hydrogen atom with a partial positive charge (δ+). This creates a dipole moment in the molecule.
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Synthesized Answer
The image illustrates four examples of covalent bonding, where atoms share electrons to achieve a more stable electron configuration.
1.
Chlorine (Cl₂): Two chlorine atoms, each needing one more electron to complete their octet, share one pair of electrons to form a
single covalent bond. The bond is nonpolar.
2.
Oxygen (O₂): Two oxygen atoms, each needing two more electrons, share two pairs of electrons to form a
double covalent bond. The bond is nonpolar.
3.
Nitrogen (N₂): Two nitrogen atoms, each needing three more electrons, share three pairs of electrons to form a
triple covalent bond. The bond is nonpolar.
4.
Hydrogen Chloride (HCl): A hydrogen atom (needing one electron to fill its first shell) and a chlorine atom (needing one electron to complete its octet) share one pair of electrons to form a
single covalent bond. Because chlorine is much more electronegative than hydrogen, this bond is
polar covalent, creating a dipole in the molecule.
In all cases, the driving force for bond formation is the tendency of atoms to achieve a stable electron configuration, typically a full outer shell (octet rule for most elements, duet rule for hydrogen). The number of bonds formed depends on the number of electrons each atom needs to share to reach this stable state.
Parent Tip: Review the logic above to help your child master the concept of covalent compounds list.
