To model a neutral atom of lithium-7 (Li-7), you need to consider the following:
- Atomic Number: Lithium has an atomic number of 3, which means it has 3 protons.
- Mass Number: The mass number of lithium-7 is 7. This means the total number of protons and neutrons together equals 7.
- Neutrons: Since lithium has 3 protons (as per the atomic number), and to find the number of neutrons, you subtract the number of protons from the mass number: \[ \text{Neutrons} = \text{Mass Number} - \text{Protons} = 7 - 3 = 4 \]
- Electrons: A neutral atom means that the number of protons equals the number of electrons. Hence, a neutral lithium atom has 3 electrons.
In summary, a neutral lithium-7 atom has:
- 3 protons
- 4 neutrons
- 3 electrons
When visualizing this in a simple atomic model:
- You would typically represent the nucleus containing 3 protons and 4 neutrons.
- The electrons would be drawn in orbits around the nucleus (typically 2 in the first shell and 1 in the second shell for lithium).
You'd need to select or draw a picture that shows a nucleus with 3 positively charged particles (protons) and 4 neutral particles (neutrons), along with 3 negatively charged electrons orbiting this nucleus.
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