Difference Wiki

Atomic Radius vs. Ionic Radius: What's the Difference?

Edited by Huma Saeed || By Sumera Saeed || Published on January 7, 2024
Atomic radius refers to the distance from the nucleus to the outermost electron shell in a neutral atom, whereas ionic radius is the radius of an atom's ion, altered by loss or gain of electrons.

Key Differences

Atomic radius and ionic radius are key concepts in chemistry, each defining the size of an atom or ion. The atomic radius is the distance from an atom's nucleus to its outermost electron shell in a neutral state. In contrast, the ionic radius is the size of an atom's ion, which changes when the atom gains or loses electrons, becoming either negatively or positively charged.
Sumera Saeed
Jan 07, 2024
The atomic radius is determined by the number of electron shells and the effective nuclear charge. As the atomic number increases, the atomic radius usually increases due to the addition of more electron shells. However, the ionic radius is influenced by the atom's charge; cations (positively charged ions) typically have a smaller radius than the original atom due to the loss of an electron shell, while anions (negatively charged ions) have a larger radius due to increased electron-electron repulsion.
Sumera Saeed
Jan 07, 2024
Trends in atomic radius are observed across the periodic table. Elements in the same group (vertical column) generally have increasing atomic radii down the group, while elements in the same period (horizontal row) have decreasing atomic radii across the period. The ionic radius, however, varies based on the specific ionization process and is not as straightforward, often deviating from the trends seen in atomic radii.
Huma Saeed
Jan 07, 2024
The measurement of atomic radius is usually done through X-ray crystallography or other spectroscopic methods in a neutral atom. In contrast, the ionic radius is often measured in crystalline ionic compounds, where ions are in a lattice structure. This difference in measurement contexts reflects the distinct nature of atomic and ionic radii.
Janet White
Jan 07, 2024
Both atomic and ionic radii play significant roles in understanding chemical bonding and reactivity. The atomic radius is crucial for predicting covalent bonding distances and van der Waals forces, while the ionic radius is important in determining the properties of ionic compounds, including their solubility, crystal structure, and melting points.
Janet White
Jan 07, 2024
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Comparison Chart

Definition

Distance from nucleus to outermost electron shell in a neutral atom
Radius of an atom's ion, altered by electron loss or gain
Sumera Saeed
Jan 07, 2024

Influencing Factors

Number of electron shells, effective nuclear charge
Ion charge, electron-electron repulsion in ions
Huma Saeed
Jan 07, 2024

Trends in Periodic Table

Increases down a group, decreases across a period
Varies based on ionization, not straightforward
Sumera Saeed
Jan 07, 2024

Measurement Method

X-ray crystallography, spectroscopy in neutral atoms
Measured in crystalline ionic compounds
Janet White
Jan 07, 2024

Role in Chemistry

Predicts covalent bonding distances, van der Waals forces
Determines properties of ionic compounds
Sumera Saeed
Jan 07, 2024
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Atomic Radius and Ionic Radius Definitions

Atomic Radius

Atomic radius decreases across a period.
Oxygen has a smaller atomic radius compared to beryllium.
Sumera Saeed
Dec 18, 2023

Ionic Radius

Ionic radius is the size of an ion in a crystal lattice.
The ionic radius of Na+ is smaller than that of Na.
Sumera Saeed
Dec 18, 2023

Atomic Radius

It's influenced by the number of electron shells.
The atomic radius of elements increases with higher shell numbers.
Sumera Saeed
Dec 18, 2023

Ionic Radius

Cations have smaller ionic radii than their neutral atoms.
The ionic radius of Mg2+ is smaller than a magnesium atom.
Sumera Saeed
Dec 18, 2023

Atomic Radius

The atomic radius determines van der Waals forces.
Larger atomic radii result in weaker van der Waals forces.
Aimie Carlson
Dec 18, 2023

Ionic Radius

The ionic radius impacts solubility and melting points.
Smaller ionic radii generally lead to higher melting points in salts.
Sumera Saeed
Dec 18, 2023

Atomic Radius

Atomic radius is the distance from an atom's nucleus to its outermost electron.
The atomic radius of helium is smaller than that of neon.
Sumera Saeed
Dec 18, 2023

Ionic Radius

Anions have larger ionic radii than their neutral atoms.
Chloride ions have a larger ionic radius than chlorine atoms.
Huma Saeed
Dec 18, 2023

Atomic Radius

It increases down a group in the periodic table.
Potassium has a larger atomic radius than lithium.
Sumera Saeed
Dec 18, 2023

Ionic Radius

Ionic radius affects the crystal structure of salts.
The ionic radius ratio influences the formation of cubic or tetrahedral lattices.
Sumera Saeed
Dec 18, 2023

FAQs

How does atomic radius change across the periodic table?

Decreases across a period, increases down a group.
Sumera Saeed
Jan 07, 2024

What is ionic radius?

The size of an ion in a crystal lattice.
Huma Saeed
Jan 07, 2024

What is atomic radius?

Distance from an atom's nucleus to its outermost electron shell.
Sumera Saeed
Jan 07, 2024

How do you measure ionic radius?

In ionic compounds within a crystal lattice.
Harlon Moss
Jan 07, 2024

Why do cations have a smaller ionic radius?

Loss of an electron shell reduces size.
Janet White
Jan 07, 2024

Why are anions larger in ionic radius?

Added electrons increase electron-electron repulsion.
Janet White
Jan 07, 2024

What affects the ionic radius?

The charge of the ion and electron-electron repulsion.
Sumera Saeed
Jan 07, 2024

How is atomic radius measured?

Through methods like X-ray crystallography.
Harlon Moss
Jan 07, 2024

What role does atomic radius play in chemistry?

Important for understanding bonding and molecular structure.
Sumera Saeed
Jan 07, 2024

Do ionic radii follow clear trends like atomic radii?

Trends are less straightforward due to varying ion charges.
Janet White
Jan 07, 2024

What's the difference in atomic radius among isotopes?

Generally negligible, as isotopes have the same electron configuration.
Sumera Saeed
Jan 07, 2024

How does ionic radius influence crystal structure?

Determines the type of crystal lattice formed.
Sumera Saeed
Jan 07, 2024

What's a notable trend for atomic radius in the periodic table?

Smaller radii for elements with higher atomic numbers in a period.
Janet White
Jan 07, 2024

How does the effective nuclear charge affect atomic radius?

Higher charge pulls electrons closer, reducing radius.
Sumera Saeed
Jan 07, 2024

Can atomic radius predict chemical reactivity?

Yes, it helps in predicting reactivity trends.
Janet White
Jan 07, 2024

Why is atomic radius important in van der Waals forces?

Larger radii have weaker van der Waals interactions.
Janet White
Jan 07, 2024

Can ionic radius change with coordination number?

Yes, it can vary with different coordination numbers in crystals.
Harlon Moss
Jan 07, 2024

How does ionic radius affect chemical properties?

Influences solubility, crystal structure, and melting points.
Sumera Saeed
Jan 07, 2024

Is ionic radius the same in different compounds?

It can vary depending on the ionic environment.
Sumera Saeed
Jan 07, 2024

Do ions always have different radii than their neutral atoms?

Yes, due to changes in electron count and structure.
Aimie Carlson
Jan 07, 2024
About Author
Written by
Sumera Saeed
Sumera is an experienced content writer and editor with a niche in comparative analysis. At Diffeence Wiki, she crafts clear and unbiased comparisons to guide readers in making informed decisions. With a dedication to thorough research and quality, Sumera's work stands out in the digital realm. Off the clock, she enjoys reading and exploring diverse cultures.
Edited by
Huma Saeed
Huma is a renowned researcher acclaimed for her innovative work in Difference Wiki. Her dedication has led to key breakthroughs, establishing her prominence in academia. Her contributions continually inspire and guide her field.

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