# Question Video: Identifying the 𝑁 : 𝑍 Ratio for Stable Light Elements Chemistry

What is the ratio of 𝑁:𝑍 in stable, light elements?

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### Video Transcript

What is the ratio of 𝑁 to 𝑍 in stable, light elements? (A) One to one, (B) one to 1.5, (C) one to two, or (D) two to one.

The ratio of 𝑁 to 𝑍, sometimes expressed as a fraction of 𝑁 over 𝑍, is the ratio of the number of neutrons, 𝑁, to the number of protons, 𝑍, in the nucleus of a given element. This ratio helps predict the stability of an atomic nucleus. The other determining factor for the stability of nuclei is the total number of nucleons. The total number of nucleons is the sum of the number of neutrons and protons, or 𝑁 plus 𝑍.

In very large nuclei, there is often potentially overpowering electrostatic repulsion between the larger number of positively charged protons. This can be reduced if the large atomic nucleus is mostly made up of neutrally charged neutrons that cause no electrostatic repulsion. Elements with less than 20 protons in their nuclei are considered to be light elements. These light elements are stable when the number of neutrons is equal to the number of protons. If the number of neutrons and protons are equal, then the ratio of 𝑁 to 𝑍 will be one to one.

The question asks us to identify the ratio of 𝑁 to 𝑍 for stable, light elements. We can see that the correct ratio is answer choice (A). So, what is the ratio of 𝑁 to 𝑍 in stable, light elements? The correct answer is answer choice (A), one to one.