QQuestionChemistry
QuestionChemistry
"How many protons, neutrons, and electrons are present in an atom of gold (Au) with a mass number of 197?
A. 197 protons, 276 neutrons, 79 electrons
B. 79 protons, 118 neutrons, 79 electrons
C. 79 protons, 197 neutrons, 118 electrons
D. 118 protons, 72 neutrons, 118 electrons"
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Answer
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Step 1:Let's solve this step by step:
Step 2:: Understand the atomic structure
- For any atom, the number of protons determines the element's identity - The atomic number represents the number of protons - Mass number = number of protons + number of neutrons - In a neutral atom, the number of electrons equals the number of protons
Step 3:: Identify the atomic number of gold (Au)
- Gold's atomic number is 79 - This means a neutral gold atom has 79 protons and 79 electrons
Step 4:: Calculate the number of neutrons
- $$\text{Neutrons} = 197 - 79 = 118
- Mass number = 197 - Number of neutrons = Mass number - Number of protons
Step 5:: Verify the composition
- Protons: 79 - Neutrons: 118 - Electrons: 79
Step 6:: Check the given options
79 \text{ protons}, 118 \text{ neutrons}, 79 \text{ electrons}
- Option B matches our calculation:
Final Answer
B. 79 protons, 118 neutrons, 79 electrons
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