Question

part 3 isotopes: use the information filled into the table to help you fill in the blanks.

1. explain the difference between an atom and an isotope.

1. what are some similarities between an atom and an isotope?

1. draw a bohr model for the two different isotopes listed above for carbon.

1. determine the average atomic mass for the following isotopes.

a. ¹²⁷i (80%), ¹²⁶i (17%), ¹²⁸i (3%)
b. gold - 197 (50%), gold - 198 (50%)

1. an element has three isotopes with the following mass numbers: 39, 40 and 41. the average atomic mass is 39.10 amu. which isotope is the most abundant? how do you know?

1. an element has three isotopes with their respective abundances a (12%), j (74%), and m (15%). which isotope will the average mass be closest to?

Explanation:

Step1: Define atom and isotope

An atom is the smallest unit of an element. Isotopes are atoms of the same element with different numbers of neutrons.

Step2: List similarities

Both atoms and isotopes of an element have the same number of protons and electrons (in neutral state), and they belong to the same element.

Step3: Bohr - model drawing (conceptually)

For Carbon - 12 and Carbon - 13, both have 6 protons and 6 electrons. Carbon - 12 has 6 neutrons and Carbon - 13 has 7 neutrons. In the Bohr model, 6 electrons are arranged in energy levels around the nucleus with 6 protons and respective neutrons in the nucleus.

Step4: Calculate average atomic mass for a

The formula for average atomic mass is $\sum_{i}(m_i\times \text{abundance}_i)$. For iodine isotopes: $(127\times0.80)+(126\times0.17)+(128\times0.03)=101.6 + 21.42+3.84 = 126.86$ amu.

Step5: Calculate average atomic mass for b

For gold isotopes: $(197\times0.50)+(198\times0.50)=98.5 + 99=197.5$ amu.

Step6: Determine most abundant isotope

The average atomic mass is closer to the mass of the most abundant isotope. Since the average atomic mass is 39.10 amu and the mass - numbers are 39, 40 and 41, the isotope with mass - number 39 is the most abundant as 39.10 is closest to 39.

Step7: Predict average mass closeness

The average mass will be closest to the isotope with the highest abundance. Here, isotope J with 74% abundance will have the average mass closest to its mass.

Answer:

1. An atom is the basic unit of an element. Isotopes are atoms of the same element with different neutron numbers.
2. They have the same number of protons and electrons (in neutral state) and are of the same element.
3. For Carbon - 12 and Carbon - 13, 6 electrons orbit around a nucleus with 6 protons and 6 or 7 neutrons respectively.
4. a. 126.86 amu; b. 197.5 amu
5. The isotope with mass - number 39 is the most abundant as the average atomic mass of 39.10 amu is closest to 39.
6. The isotope J, because it has the highest abundance (74%).