Periodic Trends in Chemistry

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Questions and Answers

Which of the following describes ionization energy?

The size of the electron cloud around an atom

The energy needed to remove an electron from an atom (correct)

The ability of an atom to attract electrons

The distance from the nucleus to the outermost shell

The ionic radius increases from left to right across a period.

False

Which element has the largest atomic radius?

Francium

The ionic radius of a cation is usually _____ than the ionic radius of its neutral atom.

smaller Signup and view all the answers

Match the following terms with their definitions:

Atomic radius = Distance from the nucleus to the outermost shell Cation = Positively charged ion Anion = Negatively charged ion Electron affinity = Energy change when an electron is added to an atom Signup and view all the answers

What happens to atomic radius as you move down a group in the periodic table?

It increases Signup and view all the answers

Electronegativity increases as you move from left to right across a period.

True Signup and view all the answers

What occurs to the ionic radius when an atom gains an electron?

It increases Signup and view all the answers

What happens to ionization energy as you move from left to right across a period?

It increases Signup and view all the answers

Electronegativity increases as you move from top to bottom in a group.

False Signup and view all the answers

What is the main characteristic of a non-metal in terms of atomic radius?

Small atomic radius Signup and view all the answers

When an atom accepts an electron to form an anion, the energy __________ is released.

affinity Signup and view all the answers

Match the following properties to their corresponding types:

Big atomic radius = Metallic property High ionization energy = Non-metallic property Good conductor = Metallic property Low electronegativity = Metallic property Signup and view all the answers

Which property tends to increase as you move from top to bottom on the periodic table?

Atomic size Signup and view all the answers

It is easier for an atom with more valence electrons to accept an electron.

True Signup and view all the answers

What element is known to be the most electronegative?

Fluorine Signup and view all the answers

Study Notes

Periodic Trends

Periodic Law: Elements' physical and chemical properties vary periodically with increasing atomic number.

Atomic Radius

Defined as the distance from the nucleus to the outermost electron shell in a neutral atom.
Trend: Increases down a group (top to bottom) due to higher energy levels further from the nucleus. Decreases across a period (left to right) due to increasing nuclear attraction, pulling electrons closer.
Example: Francium is the largest, fluorine the smallest.

Ionic Radius

The distance from the nucleus to the outermost electron orbital of an ion.
Cations: Positively charged ions. Losing electrons leads to a smaller radius as repulsion decreases and nuclear attraction increases.
Anions: Negatively charged ions. Gaining electrons increases electron repulsion, expanding the electron cloud and increasing the radius.
Trend: Increases down a group, decreases across a period. Ions with the same charge will follow this same trend, but a cation will generally be smaller than its corresponding anion.

Ionization Energy

The energy required to remove an electron from an atom. First ionization energy is for the first electron, and subsequent ionization energies follow.
Trend: Increases across a period (left to right) due to greater nuclear attraction. Decreases down a group (top to bottom) due to greater distance from the nucleus.
Relationship to Atomic Radius: Higher ionization energy corresponds to a smaller atomic radius.

Electron Affinity

Energy released when an atom accepts an electron to form an anion in the gaseous state.
Trend: Increases across a period (left to right) as atoms that are closer to a stable configuration (noble gases) readily accept electrons. Decreases down a group (top to bottom) as outer electrons are further from the nucleus.

Electronegativity

An atom's ability to attract electrons and gain a negative charge.
Trend: Increases across a period (left to right) as atomic structure approaches a stable configuration. Decreases down a group due to increasing distance and shielding of nuclear attraction.
Example: Fluorine is the most electronegative element.

Metallic and Nonmetallic Properties

Metallic Properties: Large atomic radius, low ionization energy, low electronegativity, low electron affinity, good conductors. Increase down a group, decrease across a period.
Nonmetallic Properties: Small atomic radius, high ionization energy, high electronegativity, high electron affinity, good insulators. Increase across a period, decrease down a group.

Summary of Trends

Down a group: Atomic radius, ionic radius, and metallic properties increase; electron affinity and ionization energy decrease.
Across a period: Atomic radius and metallic properties decrease; ionization energy, electron affinity, and electronegativity increase.

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Description

Explore the periodic law and trends in atomic and ionic radii. Understand how these properties change across periods and down groups in the periodic table. This quiz covers definitions, trends, and examples of atomic and ionic radii.