Unit 1: Atomic Structure and Properties

An element has two naturally occurring isotopes: isotope A (mass 62.93 u, 69.17%) and isotope B (mass 64.93 u, 30.83%). What is the element?

Which of the following electron configurations represents a ground-state atom of phosphorus (Z = 15)?

Calculate the number of moles in 48.0 g of oxygen gas (O₂). (Molar mass of O = 16.00 g/mol)

Which trend correctly describes ionization energy across a period (left to right)?

Which of the following has the smallest atomic radius?

Which of the following correctly lists the atoms in order of increasing first ionization energy?

The photoelectron spectrum (PES) of an unknown element shows peaks with relative heights of 2, 2, 6, 2, 3. The element is most likely

Which of the following species has the largest atomic/ionic radius?

Which electron configuration represents a ground-state atom of calcium?

The successive ionization energies (in kJ/mol) for an element X are: 578, 1817, 2745, 11578, 14842. Element X is most likely in which group?

Which of the following elements has the highest electronegativity?

The electron configuration of Cu is [Ar] 3d¹⁰ 4s¹ rather than [Ar] 3d⁹ 4s². The best explanation for this is

Isotopes of an element differ in their number of:

The photoelectron spectrum (PES) of an atom shows:

Electron configuration for element with atomic number 26 (Fe) is:

Ionization energy generally increases across a period because:

Coulomb's law in atomic structure explains:

Atomic radius generally decreases across a period because:

The mass spectrometer is used to determine:

Effective nuclear charge ([math]) is:

Electron affinity is:

The Aufbau principle states that electrons fill:

Hund's rule states that electrons:

Based on the ionization energy data, element X is most likely in which group of the periodic table?

Which element is most likely represented by this photoelectron spectrum?

Which of the following best explains the trend in atomic radii across Period 3?

What is the energy of the photon emitted during this electron transition?

Which of the following best explains why oxygen has a lower first ionization energy than nitrogen?

What is the average atomic mass of element X?

Which of the following best explains the trend in ionic radii for these isoelectronic species?

Based on these properties, which group does Element Z belong to?

A mass spectrum of a pure element shows two peaks: one at m/z = 63 (69.2% abundance) and one at m/z = 65 (30.8% abundance). Which of the following is the best estimate of the element's average atomic mass?

An atom has 26 protons, 30 neutrons, and 23 electrons. Which of the following correctly describes this species?

A sample of element X is analyzed by mass spectrometry and produces two peaks: one at m/z = 63 with 69.2% relative abundance and one at m/z = 65 with 30.8% relative abundance. The average atomic mass of element X is approximately

Which of the following atoms would have the smallest first ionization energy? \nI. Na II. Mg III. Cs IV. F