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Ch.2 - Atoms & Elements
Chapter 2, Problem 50

A helium nucleus has two protons and two neutrons. How many electrons does it take to equal the mass of a helium nucleus?

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Atomic Structure

An atom consists of a nucleus containing protons and neutrons, surrounded by electrons in orbitals. The number of protons defines the element, while neutrons contribute to the atomic mass. In helium, the nucleus has two protons and two neutrons, making it a stable and light element.
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Mass of Subatomic Particles

The mass of subatomic particles varies, with protons and neutrons having a mass of approximately 1 atomic mass unit (amu) each, while electrons are significantly lighter, about 1/1836 of a proton's mass. This difference is crucial when comparing the mass of electrons to that of a nucleus.
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Mass-Electron Equivalence

To determine how many electrons would equal the mass of a helium nucleus, one must compare the total mass of the nucleus (approximately 4 amu) to the mass of an electron. Since one electron has a mass of about 0.00055 amu, it would take a large number of electrons to match the mass of the helium nucleus.
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