When two hydrogen atoms combine to form a hydrogen molecule (H2), what type of bond is formed between the two hydrogen atoms?

Introduction / Context:
This basic chemistry question focuses on the type of chemical bond that holds two hydrogen atoms together in a hydrogen molecule, H2. Bond type recognition is fundamental for understanding how atoms share or transfer electrons to reach more stable electronic configurations. Hydrogen provides a simple example of covalent bonding, which is widely used to illustrate the concept of electron sharing.

Given Data / Assumptions:

• Each hydrogen atom has one electron in its outer shell.
• The stable configuration for hydrogen resembles the helium configuration with two electrons in the first shell.
• In H2, two hydrogen atoms combine to form a diatomic molecule.
• We must classify the bond as hydrophobic, ionic, covalent, or hydrophilic.

Concept / Approach:
In a covalent bond, atoms share one or more pairs of electrons. For hydrogen, sharing one pair of electrons between two atoms allows each atom to feel as if it has two electrons in its outer shell. Ionic bonds, in contrast, involve transfer of electrons and formation of oppositely charged ions, which does not happen between identical hydrogen atoms. Hydrophobic and hydrophilic describe interactions with water, not the basic chemical bond inside a molecule. Therefore, the bond in H2 is a simple single covalent bond formed by sharing an electron pair.

Step-by-Step Solution:
Step 1: Consider the electron configuration of a hydrogen atom. Each hydrogen atom has 1 electron in the first shell and wants 2 electrons for stability. Step 2: Consider what happens when two hydrogen atoms approach each other. They can share their electrons so that both atoms effectively have access to 2 electrons. Step 3: Identify the bond type. Sharing of one pair of electrons between the two atoms is the definition of a single covalent bond. Step 4: Compare with other bond types. No electron transfer occurs, so the bond cannot be ionic.

Verification / Alternative check:
Lewis dot structures show each hydrogen atom with one dot representing one electron. When they form H2, the two dots become a shared pair between the symbols H and H. This is a classic textbook example of a covalent bond. Additionally, both atoms are identical and have equal attraction for the shared electrons, confirming that the bond is a non polar covalent bond. This matches the general explanation found in basic chemistry texts for the hydrogen molecule.

Why Other Options Are Wrong:
Option A: Hydrophobic describes the tendency of non polar groups to avoid water and does not name a bond between atoms. Option B: Ionic bonding involves electron transfer and formation of ions, which is not possible between two identical hydrogen atoms in this case. Option D: Hydrophilic describes an attraction to water and is not a type of chemical bond linking two atoms.

Common Pitfalls:
Some learners confuse terms used for interactions in biology, such as hydrophobic and hydrophilic, with fundamental chemical bond types. Others think any strong interaction might be ionic, but ionic bonds always involve ions with full charges. Remember that hydrogen molecule H2 is the simplest example of a covalent bond formed by equal sharing of a pair of electrons between two identical atoms.

Final Answer:
The two hydrogen atoms in H2 are joined by a Covalent bond.