Ch 3 - Periodic Properties of the Elements (Expectations)

What defines the grouping of elements into the same group or family on the periodic table?

Elements in the same group have similar properties and are in the same column on the periodic table.

How are transition metals and inner transition metals uniquely categorized on the periodic table?

Transition metals are located in the d-block, while inner transition metals (lanthanides and actinides) are in the f-block.

Describe the electron configuration anomaly observed in chromium (Cr).

Chromium has the electron configuration [Ar] 3d⁵ 4s¹ rather than [Ar] 3d⁴ 4s² due to extra stabilization of the half-filled d subshell.

Explain the Pauli Exclusion Principle related to electron configurations.

The Pauli Exclusion Principle states that no two electrons in an atom can have the same set of four quantum numbers.

What trend in atomic radius can be observed across a period and down a group in the periodic table?

Atomic radius decreases across a period due to increasing effective nuclear charge and increases down a group due to increasing principal quantum number.

Define isoelectronic species and give an example.

Isoelectronic species are atoms or ions with identical electron configurations. For example, Na⁺, Mg²⁺, O²⁻, and F⁻ are isoelectronic with Ne.

How does the ionic radius of cations and anions compare to their parent atoms?

Cations have a smaller radius than their parent atoms due to the loss of electrons, while anions have a larger radius due to gain of electrons which decreases Zeff.

What principle explains that electrons occupy orbitals in order of increasing energy?

The Aufbau Principle dictates that electrons fill orbitals starting with the lowest energy levels first.

Describe Hund's Rule and its significance in orbital filling.

Hund's Rule states that electrons will fill degenerate orbitals singly with identical spins before pairing up, which minimizes electron repulsion.

What irregularity in ionization energy can be observed between nitrogen (N) and oxygen (O)?

Oxygen has a lower first ionization energy than nitrogen due to electron-electron repulsion in its half-filled p orbital.

What are the properties of semimetals or metalloids on the periodic table?

Semimetals or metalloids are shiny solids that are brittle and serve as semiconductors.

Define the term 'effective nuclear charge' and how it affects atomic properties.

Effective nuclear charge (Zeff) is the net positive charge experienced by an electron in an atom, which influences properties like atomic radius and ionization energy.

Explain the general trend for electron affinity across a period in the periodic table.

Electron affinity typically becomes more exothermic (more negative) across a period, with exceptions for certain groups, like the noble gases.

How do noble gases typically respond in terms of electron affinity and why?

Noble gases generally have low or zero electron affinity because their electron configurations are stable, resulting in a low tendency to gain electrons.

What distinguishes main group metals from transition metals with respect to electron loss?

Main group metals usually lose all outer-shell electrons, whereas transition metals lose s orbital electrons first before d orbital electrons.