A neutral atom of an unknown element contains 35 protons, 45 neutrons, and 35 electrons.
Identify the element and justify your answer.
Determine the mass number of this atom.
If the atom forms a -1 ion, describe what happens to its electron count.
Explain why the nucleus remains unaffected when an atom gains or loses electrons.
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A scientist is comparing the first ionization energy of sodium (Na) and chlorine (Cl).
Define ionization energy and explain what it measures.
Use Coulomb’s Law to explain why chlorine has a higher first ionization energy than sodium.
Predict whether magnesium (Mg) has a higher or lower ionization energy than sodium (Na) and justify your answer.
Explain why the second ionization energy of sodium is significantly higher than its first ionization energy.
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A student is analyzing the electron configurations of elements in Period 3 of the periodic table.
Write the electron configuration for phosphorus (P).
Explain why argon (Ar) has a lower chemical reactivity than phosphorus.
Predict whether sodium (Na) or sulfur (S) has a larger atomic radius, and justify your answer.
Explain why transition metals do not always follow the standard Aufbau principle when forming ions.
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A sample of element Y is analyzed in the laboratory. It has an atomic number of 12 and two common isotopes: Y-24 and Y-25.
Write the complete electron configuration for a neutral atom of element Y.
The photoelectron spectrum of element Y includes three peaks labeled A, B, and C.
Identify the electron subshell that corresponds to each peak. Justify your answer.
The sample also contains the isotope Y-25.
i) Define the term isotope.
ii) Explain how the mass spectrum of Y would reflect the presence of both isotopes.
The first three ionization energies of element Y are shown in the table below.
Ionization level | Ionization energy (kJ/mol) |
|---|---|
1st | 738 |
2nd | 1450 |
3rd | 7730 |
Using this data, determine the number of valence electrons in element Y. Justify your answer.
Explain why the third ionization energy of element Y is significantly higher than the first and second.
Element Z has an atomic number of 13. Predict which element, Y or Z, has the greater atomic radius. Justify your answer.
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The complete photoelectron spectrum of an element in its ground state is represented below.
Based on the spectrum,
i) Write the ground-state electron configuration of the element.
ii) Identify the element.
Calculate the wavelength, in meters, of electromagnetic radiation needed to remove an electron from the valence shell of an atom of the element.
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A scientist uses photoelectron spectroscopy (PES) to analyze an unknown element. The PES spectrum shows four peaks at relative binding energies of 500 MJ/mol, 50 MJ/mol, 10 MJ/mol, and 0.9 MJ/mol.
Explain what information photoelectron spectroscopy (PES) provides about atomic structure.
Identify the most likely element corresponding to this PES spectrum and justify your choice.
Compare the ionization energy of Mg to Al, and explain which is higher.
Explain how effective nuclear charge (Zeff) influences PES peak positions.
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The following table shows the successive ionization energies (in MJ/mol) for an unknown third period element:
Ionization Step | Ionization Energy (MJ/mol) |
|---|---|
1st | 0.58 |
2nd | 1.82 |
3rd | 2.75 |
4th | 11.58 |
5th | 14.84 |
Identify the unknown element and justify your answer.
Explain why there is a large increase in ionization energy between the third and fourth electrons.
Compare the first ionization energies of Al and Si, and predict which element has the higher value.
Explain how the electron configuration of an element can be inferred from its ionization energy data.
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