Chemistry Chapter 4: Periodic Properties

Questions and Answers

Who primarily developed the periodic table?

John Dalton

Dimitri Mendeleev (correct)

J.J. Thomson

Henry Moseley

What does periodic properties predict?

Based on an element's position in the periodic table.

What does the periodic law state?

Certain sets of properties recur periodically.

What are main-group elements?

Elements found in the s or p blocks of the periodic table. Signup and view all the answers

What are transition elements?

Elements found in the d block of the periodic table. Signup and view all the answers

Define family/group in the context of the periodic table.

Columns that contain elements with similar chemical properties. Signup and view all the answers

What is electron configuration?

A notation that shows the particular orbitals occupied by electrons in an atom. Signup and view all the answers

What is the ground state of an atom?

The lowest energy state of an atom or molecule. Signup and view all the answers

What does the Pauli Exclusion Principle state?

No two electrons in an atom can have the same four quantum numbers. Signup and view all the answers

What is Coulomb's Law?

The potential energy of two charged particles depends on their charges and separation. Signup and view all the answers

What does shielding refer to in atomic structure?

The effect of repulsion by electrons in lower-energy orbitals. Signup and view all the answers

What is an effective nuclear charge?

The actual nuclear charge experienced by an electron. Signup and view all the answers

What does the Aufbau Principle indicate?

The pattern of orbital filling in an atom. Signup and view all the answers

What are valence electrons?

Electrons important in chemical bonding, in the outermost energy level. Signup and view all the answers

What are noble gases known for?

Being largely unreactive due to stable filled p orbitals. Signup and view all the answers

What distinguishes metals from nonmetals?

Metals are generally good conductors and tend to lose electrons. Signup and view all the answers

The radius of a cation is much smaller than that of the corresponding ______.

atom Signup and view all the answers

Electron affinity shows a general trend as we move down a column in the periodic table.

False Signup and view all the answers

What is ionization energy?

The energy required to remove an electron from an atom in its gaseous state. Signup and view all the answers

What describes a paramagnetic state?

An atom or ion that contains unpaired electrons. Signup and view all the answers

Study Notes

Periodic Properties and the Periodic Table

Dimitri Mendeleev created the periodic table in the 19th century, organizing elements by increasing atomic mass and grouping similar properties in columns.
Predictable properties influenced by an element's periodic table position include atomic radius, ionization energy, electron affinity, density, and metallic character.
Quantum mechanics elucidates the periodic table through the organization of electron filling in atomic orbitals.

Key Periodic Concepts

Periodic Property: A property that can be predicted based on an element's position in the periodic table.
Periodic Law: Elements arranged by increasing mass reveal recurring sets of properties.
Main-Group Elements: Elements in the s or p blocks with predictable properties based on position.
Transition Elements: Found in the d block, these elements exhibit less predictable properties.

Electron Configuration

Electron configuration details the quantum orbitals occupied by an atom's electrons (e.g., helium's configuration is 1s²).
The order of orbital filling for multi-electron atoms: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s.
Pauli Exclusion Principle: Each orbital holds a maximum of two electrons with opposite spins.
Hund's Rule: Electrons fill degenerate orbitals singly before pairing.

Important Electron Concepts

Ground State: The lowest energy state of an atom or molecule.
Orbital Diagram: A visual representation of electron configurations, using arrows to denote electron spin.
Coulomb's Law: Relates potential energy of charged particles to their charges and distance.
Effective Nuclear Charge (Z_eff): Actual nuclear charge felt by an electron, accounting for shielding by other electrons.
Shielding Effect: Lower-energy electrons repel outer electrons, reducing their effective nuclear charge.

Valence and Core Electrons

Valence Electrons: Electrons in the outermost energy level, crucial for chemical bonding.
Core Electrons: Electrons in complete energy levels and d or f sublevels.

Properties of Elements

Noble gases have completely filled p orbitals, contributing to low reactivity and stability.
Metals, located on the left and center, typically lose electrons in reactions.
Nonmetals on the upper right gain electrons during reactions.
Elements with one or two valence electrons are highly reactive, losing electrons easily.
Elements with six or seven valence electrons actively gain electrons.

Atomic Size and Trends

Atomic size increases down a column due to higher principal quantum numbers and larger orbitals.
Across a row, atomic radii decrease as effective nuclear charge increases.
Transition elements maintain constant radii across a row due to added electrons in n-1 orbitals.

Ion Properties

Ion electron configurations result from adding or subtracting electrons from a neutral atom's configuration.
Cations are smaller than their parent atoms, while anions are larger.
Ionization energy decreases down a column and increases across a row.
The first ionization is consistently lower than subsequent ionizations due to increased stability of core electrons.

Magnetic Properties

Paramagnetic: Atoms or ions with unpaired electrons, attracted by external magnetic fields.
Diamagnetic: Atoms or ions with only paired electrons, repelled by external magnetic fields.

Electron Affinities and Metallic Character

Electron affinity, the energy change when an atom gains an electron, shows variability down columns and generally becomes more negative across rows.
Metallic character tends to increase down a column and decrease across a row.

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Explore the key concepts of periodic properties and the development of the periodic table in this flashcard quiz. Learn about the historical contributions of Dmitri Mendeleev and how elements are organized based on atomic mass and similar properties.