Question

which diagram shows the correct distribution of electrons in the electron shells of a helium atom?

Explanation:

To determine the correct electron shell diagram for a helium atom, we analyze the atomic structure of helium:

1. Atomic Number of Helium: Helium has an atomic number of 2, meaning it has 2 protons and (in a neutral atom) 2 electrons.
2. Electron Shell Rules: The first electron shell (n=1) can hold a maximum of 2 electrons. For helium, both electrons occupy the first (and only) electron shell, as it has no additional shells (helium is a noble gas with a full valence shell in the first shell).

Analyzing the Diagrams (from the description):

• The first diagram (with “1P, 0N” in the nucleus) likely represents a hydrogen-like atom but with 1 proton (incorrect for helium, which has 2 protons). However, if we assume a typo or simplified nucleus labeling, the key is electron count: a single electron shell with 2 electrons? Wait, no—wait, helium has 2 electrons. Wait, the first diagram shown has 1 electron? No, maybe the user’s diagram has:

Wait, the user’s first diagram: nucleus with “1P, 0N” (1 proton, 0 neutrons) and 1 electron? That would be hydrogen. The second diagram: nucleus with “5P” (5 protons, so boron) and multiple shells.

Wait, there’s a mistake—helium has 2 protons, 2 electrons, and 2 neutrons (usually). But the correct electron configuration for helium is 2 electrons in the first shell (no second shell).

If the options are:

• Option 1: 1 electron in the first shell (incorrect, helium has 2).
• Option 2: Multiple shells (incorrect, helium has only one shell with 2 electrons).

Wait, maybe the first diagram is mislabeled, but the correct diagram for helium should have:

• A nucleus with 2 protons (and 2 neutrons, typically).
• A single electron shell (the first shell) containing 2 electrons.

Assuming the first diagram (despite the “1P, 0N” nucleus, which might be a simplification) has a single shell with 2 electrons? No—wait, the user’s first diagram shows 1 electron? No, the first diagram’s nucleus is “1P, 0N” (1 proton) and 1 electron (hydrogen). The second diagram has a nucleus with “5P” (5 protons, boron) and multiple shells.

This suggests a possible error in the diagram labels, but the correct answer for helium’s electron shell is a single shell with 2 electrons. If the options include a diagram with:

• Nucleus (2P, 2N) and 1 shell with 2 electrons, that’s correct.

But from the given options, the only plausible one (if we ignore nucleus proton count as a simplification) is the first diagram if it has 2 electrons (but the user’s description shows 1 electron? No—maybe the user’s diagram has:

Wait, the user’s first diagram: circle (shell) with 1 electron? No. The second diagram: multiple shells.

Wait, perhaps the intended correct diagram is the one with a single electron shell (no inner/outer shells) containing 2 electrons. Since helium has only one shell, the diagram with a single shell (no additional concentric shells) and 2 electrons is correct.

Answer:

(Assuming the first diagram, despite nucleus labeling, is the one with a single shell—if the options are:
A. Diagram with 1 shell and 2 electrons (correct for helium),
B. Diagram with multiple shells (incorrect).

Then the answer is the diagram with a single electron shell (the first option, even with nucleus label error, as the second diagram has multiple shells which helium does not have).)

So the correct option is the first diagram (the one with the single electron shell, even if the nucleus is mislabeled, as the second diagram has multiple shells which helium lacks).