The symbol for calcium is "Ca" and its atomic number is 20. This means that a calcium atom has 20 protons. The most common isotope of calcium has a mass number of 40, calculated as the sum of protons and neutrons.
To find the number of neutrons, you can subtract the number of protons from the mass number:
- Mass number (40) - Number of protons (20) = Number of neutrons (20).
With this information, we can evaluate the options:
A. A calcium atom has 44 neutrons and 20 electrons.
Incorrect - A calcium atom has 20 neutrons.
B. A calcium atom has 20 protons and 24 electrons.
Incorrect - A neutral calcium atom has equal numbers of protons and electrons, so it has 20 electrons.
C. A calcium atom has 64 protons and 20 neutrons.
Incorrect - A calcium atom only has 20 protons.
D. A calcium atom has 20 protons and 24 neutrons.
Incorrect - A calcium atom typically has 20 neutrons (not 24).
E. A calcium atom has 20 protons and 44 neutrons.
Incorrect - A calcium atom has 20 neutrons (not 44).
Based on the above analysis, none of the provided options correctly describe a typical calcium atom, which has 20 protons, 20 neutrons, and 20 electrons in its most common isotope (Ca-40).
1 answer