Question

In the periodic table the metallic character with increase in atomic number (1) decreases in a period and increases in a group (2) increases in a period and decreases in a group (3) increases both in a period and in the group (4) decreases both in a period and in the group

Short answer

Option (1): decreases in a period and increases in a group.

Step-by-step solution

- Understand the trend in a period

In the periodic table, as the atomic number increases across a period from left to right, the number of protons and electrons in the atoms increase. This causes an increase in nuclear charge, which pulls the electron cloud closer to the nucleus, reducing atomic size. This leads to a decrease in metallic character. Therefore, metallic character decreases across a period.

- Understand the trend in a group

As the atomic number increases down a group, the number of electron shells increases, making atoms larger. The increased distance of the outer electrons from the nucleus makes them more easily lost, which increases the metallic character. Therefore, metallic character increases down a group.

- Combine findings

From the above analysis, it's clear that metallic character decreases across a period and increases down a group.

- Select the correct option

Based on the identified trends, option (1): 'decreases in a period and increases in a group' is the correct answer.

Key concepts

Periodic Table Trends

Periodic table trends are fundamental patterns observed across the periodic table that help predict the behavior and characteristics of elements. These trends include metallic character, atomic radius, ionization energy, and electronegativity.
Let's delve into the trend of metallic character:

• Across a Period: When moving from left to right across a period (a horizontal row) in the periodic table, the atomic number increases. This increase results in a greater number of protons and electrons in the atom. The increased nuclear charge (positive charge in the nucleus) pulls the electron cloud closer to the nucleus, causing a reduction in the size of the atom. As the electron cloud is held more tightly, the atom's ability to lose electrons (a characteristic of metals) decreases, leading to a decrease in metallic character.
• Down a Group: When moving down a group (a vertical column) in the periodic table, the number of electron shells increases, making the atoms larger. The outer electrons are further away from the nucleus and are less tightly held. This makes them easier to lose, increasing the metallic character.

Understanding these trends allows predictions about the physical and chemical properties of elements, helping students grasp the concept of periodicity in the periodic table.

Chemical Periodicity

Chemical periodicity refers to the recurring trends that are observed in the properties of elements as we move across periods and down groups in the periodic table. These trends arise due to the periodic variations in the electronic configuration of the elements.
Chemical periodicity includes:

• Metallic Character: As explained, this characteristic decreases across a period and increases down a group.
• Atomic Radius: The atomic radius decreases across a period due to increased nuclear charge pulling the electron cloud closer, whereas it increases down a group because of the addition of electron shells.
• Ionization Energy: The energy required to remove an electron from an atom increases across a period due to stronger attraction between the nucleus and electrons and decreases down a group because outer electrons are farther from the nucleus.
• Electronegativity: The tendency of an atom to attract electrons in a chemical bond increases across a period (especially from left to right) and decreases down a group.

Recognizing these periodic trends helps in predicting and understanding the chemical and physical behavior of different elements, thus simplifying the study of chemistry.

Atomic Structure

Atomic structure is the understanding of the composition and arrangement of particles within an atom. An atom consists of a nucleus containing protons and neutrons, and electrons that orbit the nucleus.
Here are key points:

• Protons: Positively charged particles found in the nucleus. The number of protons defines the atomic number of an element and its position in the periodic table.
• Neutrons: Neutrally charged particles found in the nucleus. The number of neutrons can vary in atoms of the same element, leading to different isotopes.
• Electrons: Negatively charged particles that orbit the nucleus in various energy levels (shells). The arrangement of electrons determines the chemical properties and reactivities of the element.

The periodic table is arranged based on atomic numbers, which reflect the number of protons in the nucleus. As we move across a period, electrons are added to the same shell, but the increased nuclear charge pulls these electrons closer, affecting atomic size and other properties.
Conversely, moving down a group adds more electron shells, increasing atomic radius and influencing trends like metallic character.
Understanding atomic structure not only aids in grasping periodic trends but also forms the foundation for studying chemical reactions and properties.