Question

1. why do isotopes of the same element have different masses?
2. what was the final atomic mass of beanium? which isotope of beanium is nearest the atomic mass?
3. there are 125 lime beans, 56 garbanzo beans, 39 kidney beans, and 144 green peas in a container. find the percent by number of green peas in the container. (remember: fwau)
4. an element has two isotopes, a and b. in nature, there is 80% of a and 20% of b. is the atomic mass closer to a or b? why?
5. neon has 3 isotopes, neon - 20, neon - 21, and neon - 22. the relative abundance of $^{20}ne$ is 91%, $^{21}ne$ is 0.25%, and $^{22}ne$ is 8.75%. calculate the average atomic mass for neon, expected to be found on the periodic table. (remember: fwau)

Explanation:

Step1: Recall isotope concept

Isotopes of an element have same number of protons but different number of neutrons. Mass of an atom is mainly due to protons and neutrons. Since number of neutrons vary, masses vary.

Step2: No data for Beanium in real - life

This question about Beanium cannot be answered without additional data on the masses and abundances of its isotopes.

Step3: Calculate total number of items

Total number of items = 125+56 + 39+144=364

Step4: Calculate percentage of green peas

Percent of green peas=$\frac{144}{364}\times100\%\approx39.56\%$

Step5: Determine atomic - mass closeness

The atomic mass is closer to A. Because the more abundant isotope (A with 80% abundance) has a greater influence on the weighted - average atomic mass.

Step6: Calculate average atomic mass of neon

Average atomic mass of neon =$(20\times0.91)+(21\times0.0025)+(22\times0.0875)$
$=18.2 + 0.0525+1.925$
$=20.1775$

Answer:

1. Isotopes of the same element have different masses because they have different numbers of neutrons.
2. Cannot be answered without more data.
3. Approximately 39.56%
4. Closer to A because A is more abundant.
5. 20.1775