To identify the model as representing a neutral lithium atom, the correct responses would be:
- The atomic number of lithium is three and there are three positive protons in the nucleus of this model. - This is correct because the atomic number defines the element, and since lithium has an atomic number of 3, it must have three protons.
The other options are incorrect for the following reasons:
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The model has a mass of seven amu, protons plus neutrons so it must be lithium since no other atoms can have a mass near seven amu. - This is misleading because while lithium (specifically the most common isotope) has a mass close to seven amu, there are other atoms (e.g., beryllium or boron) with similar mass values. Therefore, mass alone is not solely indicative of lithium.
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The model has four neutrons in the nucleus, neutrons can be used to identify an atom. - While the number of neutrons contributes to the atomic mass and the distinction between isotopes, it does not uniquely identify an element. Different elements can have isotopes with different neutron counts.
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This model has three negative electrons found inside its nucleus so it must be lithium. - This is incorrect because electrons are not found inside the nucleus; they orbit around it. Additionally, the number of electrons alone does not uniquely identify lithium as the presence of three electrons indicates neutrality, but does not specify the element.
In summary, the only accurate identification is based on the atomic number and the presence of three protons.