Question

While moving down a group in the periodic table, which of the following would be true? (1) All the atoms have the same number of valence electrons (2) Gram atomic volume increases (3) Electronegativity decreases (4) Metallic character decreases and the basic nature of their oxides decreases. Select the correct answer by using the following codes: (a) 1,2 and 3 (b) 2,3 and 4 (c) 2 and 3 (d) 1 and 3

Short answer

The correct answer is (a) 1, 2, and 3.

Step-by-step solution

Understand valence electrons in a group

All elements in the same group of the periodic table have the same number of valence electrons. For instance, all group 1 elements have 1 valence electron, group 2 have 2, and so on. Therefore, statement (1) fits the characteristics of elements within the same group.

Consider Gram atomic volume

Gram atomic volume generally increases as we move down a group. This is because the number of electron shells increases, making the atoms larger. Thus, statement (2) is typically true.

Evaluate Electronegativity

Electronegativity tends to decrease as we move down a group. Larger atoms with more electron shells have weaker attraction for additional electrons. Therefore, statement (3) is generally true.

Assess metallic character and oxides

Metallic character actually increases as you go down a group due to the increase in atomic size, which makes it easier for atoms to lose electrons. Conversely, the basic nature of their oxides typically increases. So, statement (4) is not correct.

Determine the correct answer

Based on the analysis: (1) is true, (2) is true, and (3) is true. Statement (4) is incorrect as it suggests metallic character decreases, which is not true down a group. Therefore, the correct answer is option (a), which includes statements 1, 2, and 3.

Key concepts

Valence Electrons

Valence electrons are the outermost electrons of an atom and play a crucial role in chemical reactions. They are the electrons that an atom can lose, gain, or share when it interacts with other atoms. Understanding valence electrons is essential for determining the chemical properties of elements and predicting how they will interact with others.

• In the periodic table, elements are arranged in groups (columns), and elements within the same group have the same number of valence electrons.
• This means that elements in the same group will exhibit similar chemical behavior.
• For example, Group 1 elements (alkali metals) have 1 valence electron, making them highly reactive and eager to lose that electron to achieve a stable electron configuration.

Moving down a group, the number of valence electrons remains the same, but these electrons are further from the nucleus due to additional electron shells. This distance affects an element's ability to attract and hold onto electrons during chemical reactions.

Atomic Volume

Atomic volume, also known as atomic size or atomic radius, refers to the space an atom occupies. As we move down a group in the periodic table, atomic volume generally increases. This increase is due to the addition of electron shells as atomic number rises.

• Each new electron shell is farther from the nucleus, thus enlarging the atom.
• Increased atomic volume affects an element's properties, such as its density and how it interacts with other atoms.

The increase in atomic volume has further consequences:

• Atoms have a larger gap between their outer electrons and the nucleus, weakening the nucleus's ability to attract those electrons.
• This makes atoms more metallic in character as they move down a group, since larger atoms more readily lose electrons.

Electronegativity

Electronegativity is a measure of an atom's ability to attract and hold onto electrons within a chemical bond. It is a critical parameter in predicting how atoms will bond and react with each other. In the periodic table, electronegativity decreases as you move down a group. This trend is due to two factors:

• Increased number of electron shells create a shielding effect, reducing the nucleus's pull on the outermost electrons.
• Larger atomic size increases the distance between the nucleus and valence electrons, further reducing attraction.

Lower electronegativity means elements are less likely to attract electrons in a bond, making them more reactive and metallic in nature. Understanding these trends helps in predicting the behavior of elements and their compounds in various chemical reactions.