QQuestionChemistry
QuestionChemistry
Determine the number of protons, electrons, and neutrons present in an atom of calcium (Ca). Explain how you determined your answer using complete sentences.
| **sodium 11 Na 22.990 ** | **magnesium 12 Mg 24.305 ** | |
| --- | --- | --- |
| potassium 19 K 39.098 | calcium 20 Ca 40.078 | scandium 21 Sc 44.956 |
| rubidium 37 Rb 85.468 | strontium 38 Sr 87.62 | yttrium 39 Y 88.906 |
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Step 1:: To determine the number of protons, electrons, and neutrons in an atom of calcium (Ca), we first need to find out its atomic number and atomic mass.
Step 2:: The atomic number of calcium is 20, which can be found in the periodic table provided.
\text{Atomic number of Ca} = 20 \Rightarrow \text{Number of protons in Ca} = 20
The atomic number represents the number of protons in an atom.
Step 3:: Since atoms are electrically neutral, the number of protons equals the number of electrons.
\text{Number of electrons in Ca} = 20
Step 4:: The atomic mass of calcium is 40.078 u (unified atomic mass units).
\text{Number of neutrons} = \frac{40.078 \, u - 20}{1.009 \, u} \approx 20.08
To find the number of neutrons, subtract the number of protons from the atomic mass and divide by the mass of a neutron (approximately 1.009 u). Since the number of neutrons is a whole number, we round it to the nearest whole number.
Step 5::
\text{Number of neutrons in Ca} = 20
Final Answer
- Number of protons in Ca: 20 - Number of electrons in Ca: 20 - Number of neutrons in Ca: 20
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