Atomic Structure And Electron Configuration
A neutral atom of calcium (Z = 20) contains 20 protons and 20 electrons. Which statement correctly explains why a Ca²⁺ ion carries a positive charge?
According to Coulomb’s law, what happens to the electrostatic force between a nucleus and an electron if the distance between them is tripled while the charges remain constant?
Which ground-state electron configuration correctly represents a neutral atom of vanadium (Z = 23)?
What is the ground-state electron configuration of the Fe³⁺ ion (Z = 26)?
A researcher measures the successive ionization energies (in kJ/mol) of an unknown element X and obtains the following data: IE₁ = 578, IE₂ = 1,817, IE₃ = 2,745, IE₄ = 11,578, IE₅ = 14,831. In which group of the periodic table is element X most likely found?
Both Mg²⁺ and Na⁺ have the electron configuration 1s² 2s² 2p⁶. Which ion holds its outermost electrons more tightly, and which principle explains this?
An atom of phosphorus (Z = 15) has the ground-state electron configuration 1s² 2s² 2p⁶ 3s² 3p³. How many of these electrons are core electrons, and how many are valence electrons?
A mountaineer at high altitude breathes air with lower oxygen partial pressure, and her body responds by producing more red blood cells over several weeks. If each hemoglobin molecule in those red blood cells contains four iron(II) ions, what is the electron configuration of each iron ion present in hemoglobin?
The first ionization energy of magnesium (738 kJ/mol) is higher than that of aluminum (577 kJ/mol), even though aluminum has a greater nuclear charge. Which explanation correctly accounts for this observation?
Which subshell fills immediately after the 4p subshell in the Aufbau filling order?
An element has the ground-state electron configuration 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁴. How many valence electrons does this atom have, and in which period and group of the periodic table is it located?
A student claims: “Fluorine (Z = 9) should have a lower first ionization energy than lithium (Z = 3) because fluorine has more electrons creating more electron-electron repulsion.” Evaluate this claim.
A laboratory technician uses a flame test to identify an unknown metal salt and observes a characteristic color. The color arises when electrons in excited states return to lower energy levels and emit photons. Which of the following correctly describes the ground-state electron configuration that the electrons return to for potassium (Z = 19)?
Two ions, O²⁻ and F⁻, are isoelectronic — both have 10 electrons. Predict which ion has a larger ionic radius and justify your answer using Coulomb’s law.
The successive ionization energies for an element Q are: IE₁ = 786 kJ/mol, IE₂ = 1,577 kJ/mol, IE₃ = 3,232 kJ/mol, IE₄ = 4,356 kJ/mol, IE₅ = 16,091 kJ/mol, IE₆ = 19,784 kJ/mol. How many valence electrons does element Q have?
A student writes the electron configuration of Cr³⁺ (Z = 24) as 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d². Identify the error and provide the correct configuration.