6 Questions
Which of the following is a reason for the decrease in atomic radius across a period?
Increasing nuclear charge and decreasing shielding
Which of the following is NOT a factor that affects atomic radius?
Electronegativity
Which trend in atomic radius is due to the addition of energy levels and increasing shielding?
Increase in atomic radius down a group
What is the unit of measurement typically used to express atomic radius?
Picometers (pm) or angstroms (Å)
What is the result of an increase in nuclear charge on atomic radius?
The atomic radius decreases
Which of the following physical properties is influenced by atomic radius?
Density
Study Notes
Atomic Radius
- Definition: The distance from the center of the nucleus to the outermost electron in an atom.
- Units: Typically measured in picometers (pm) or angstroms (Å).
Trends in Atomic Radius
-
Across a Period:
- Decreases from left to right due to increasing nuclear charge and relatively constant shielding.
- Electrons are pulled closer to the nucleus as the number of protons increases.
-
Down a Group:
- Increases due to the addition of energy levels and increasing shielding.
- The outermost electrons are farther from the nucleus as the atomic number increases.
Factors Affecting Atomic Radius
- Nuclear Charge: As the number of protons increases, the nuclear charge increases, pulling electrons closer to the nucleus.
- Shielding: The ability of inner electrons to shield outer electrons from the nuclear charge, resulting in a larger atomic radius.
- Number of Electron Shells: As the number of electron shells increases, the atomic radius increases due to the additional energy levels.
Importance of Atomic Radius
- Chemical Properties: Atomic radius influences chemical properties such as reactivity, electronegativity, and ionization energy.
- Physical Properties: Atomic radius affects physical properties such as melting and boiling points, density, and atomic volume.
Atomic Radius
- Atomic radius is the distance from the center of the nucleus to the outermost electron in an atom.
Units of Atomic Radius
- Atomic radius is typically measured in picometers (pm) or angstroms (Å).
Trends in Atomic Radius
Across a Period
- Atomic radius decreases from left to right across a period due to increasing nuclear charge and relatively constant shielding.
- Electrons are pulled closer to the nucleus as the number of protons increases.
Down a Group
- Atomic radius increases down a group due to the addition of energy levels and increasing shielding.
- The outermost electrons are farther from the nucleus as the atomic number increases.
Factors Affecting Atomic Radius
- Increasing nuclear charge pulls electrons closer to the nucleus, decreasing atomic radius.
- Shielding by inner electrons reduces the nuclear charge, resulting in a larger atomic radius.
- The addition of electron shells increases atomic radius due to the additional energy levels.
Importance of Atomic Radius
- Atomic radius influences chemical properties such as reactivity, electronegativity, and ionization energy.
- Atomic radius affects physical properties such as melting and boiling points, density, and atomic volume.
Learn about atomic radius, its definition, units, and trends across periods and down groups in the periodic table.
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