Unit5: Periodic Trends

Front

Atomic radius

Back

The distance from the nucleus to the outermost shell of electrons.

Answer explanation

The atomic radius is defined as the distance from the nucleus to the outermost shell of electrons, making option b) the correct choice. The other options describe different atomic properties.

Front

In which units is the atomic radius typically measured?

Back

Picometers (pm) or angstroms (Å)

Answer explanation

The atomic radius is typically measured in picometers (pm) or angstroms (Å) because these units are suitable for the small scale of atomic dimensions, making option c) the correct choice.

Front

How does the atomic radius change across a period from left to right?

Back

Decreases

Answer explanation

The atomic radius decreases across a period from left to right due to increasing nuclear charge, which pulls electrons closer to the nucleus, resulting in a smaller atomic size.

Front

How does the atomic radius change down a group?

Back

Increases

Answer explanation

The atomic radius increases down a group due to the addition of electron shells, which outweighs the increase in nuclear charge, resulting in larger atomic size.

Front

What is the first ionization energy?

Back

The energy required to remove the outermost electron from a neutral atom.

Answer explanation

The first ionization energy is defined as the energy required to remove the outermost electron from a neutral atom, making option b the correct choice. This process is crucial in understanding atomic behavior.

Front

How does the first ionization energy generally change across a period?

Back

Increases

Answer explanation

The first ionization energy generally increases across a period due to increasing nuclear charge, which attracts electrons more strongly, making them harder to remove. Thus, the correct answer is a) Increases.

Front

How does the first ionization energy change down a group?

Back

Decreases

Answer explanation

The first ionization energy decreases down a group due to increased atomic size and shielding effect, making it easier to remove the outermost electron. Thus, the correct answer is b) Decreases.

Front

Electronegativity

Back

The tendency of an atom to attract and hold onto electrons in a chemical bond.

Answer explanation

Electronegativity is defined as the tendency of an atom to attract and hold onto electrons in a chemical bond, making option c the correct choice. The other options describe different concepts related to atomic structure.

Front

How does electronegativity change across a period?

Back

Increases

Answer explanation

Electronegativity increases across a period due to the increasing nuclear charge, which attracts electrons more strongly. This trend is observed as you move from left to right in the periodic table.

Front

How does electronegativity change down a group?

Back

Decreases

Answer explanation

Electronegativity decreases down a group due to increased atomic size and shielding effect, which reduces the nucleus's ability to attract bonding electrons. Thus, the correct answer is b) Decreases.