Let's go through the worksheet and
correctly answer each question based on the
molecular structure of water (H₂O), using scientific reasoning. I'll provide
clear explanations for each answer.
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Model 1 - The Molecular Structure of Water
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Question 1: How many hydrogen atoms are in a molecule of water?
✔ Answer: There are
2 hydrogen atoms in a molecule of water.
🔹
Explanation:
The chemical formula for water is
H₂O, which means each water molecule consists of
two hydrogen (H) atoms and one oxygen (O) atom. This is clearly shown in the diagram where two hydrogen atoms are bonded to one oxygen atom.
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Question 2: How many oxygen atoms are in a molecule of water?
✔ Answer: There is
1 oxygen atom in a molecule of water.
🔹
Explanation:
Again, from the formula H₂O, we know that only
one oxygen atom is present per water molecule. The diagram also shows a single central oxygen atom bonded to two hydrogens.
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Question 3: What holds the hydrogen atoms to the oxygen atom?
✔ Answer: The
covalent bonds hold the hydrogen atoms to the oxygen atom.
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Explanation:
A
covalent bond is formed when atoms
share electrons. In water, each hydrogen atom shares a pair of electrons with the oxygen atom, forming two covalent bonds. These bonds are represented by the lines connecting the hydrogen and oxygen atoms in the model.
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Question 4: The shading around the molecule represents the relative density of electrons shared by the atoms. What does this indicate about the density of electrons around the oxygen atom as compared to the density of electrons around the hydrogen atoms?
✔ Answer: The
electron density is higher around the oxygen atom than around the hydrogen atoms.
🔹
Explanation:
The
shading in the electron density model shows where electrons are more likely to be found. Oxygen is
more electronegative than hydrogen, meaning it attracts shared electrons more strongly. As a result:
- The
shared electrons spend more time near the oxygen atom.
- This creates a
partial negative charge (δ⁻) on the oxygen.
- The hydrogen atoms become
partially positive (δ⁺) due to the lack of electron density.
So, the
electron density is greater around oxygen, which is why the shading is darker or more concentrated around the oxygen atom. This unequal sharing of electrons leads to
polarity in the water molecule — a key reason for its unique properties like hydrogen bonding and high boiling point.
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✔ Summary of Correct Answers:
| Question | Answer |
|--------|--------|
| 1 | 2 hydrogen atoms |
| 2 | 1 oxygen atom |
| 3 | Covalent bonds |
| 4 | Electron density is higher around the oxygen atom because oxygen is more electronegative than hydrogen |
> 💡
Note: Your original answers were mostly correct, but
Question 4 could be improved for accuracy. Saying “the bond around the oxygen is stronger” is misleading — the
bond strength isn’t what’s being shown; it’s
electron distribution due to polarity.
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Would you like me to generate a version of this with
color-coded responses as instructed in the directions?
Parent Tip: Review the logic above to help your child master the concept of properties of water worksheet answer key.
