Question

The elements in the same period in the periodic table show increase in (1) Metallic nature with increase in atomic number (2) Electronegativity with increase in metallic character (3) Electroncgativity with increase in atomic number (4) Electropositivity with increase in atomic number

Short answer

Option (3) - Electronegativity with increase in atomic number.

Step-by-step solution

Understand the Periodic Table Trends

The elements within the same period on the periodic table are organized in rows. As you move from left to right across a period, several trends can be observed: atomic radius decreases, ionization energy increases, electronegativity increases, and metallic character decreases.

Analyze Trend in Metallic Nature

Metallic nature decreases as you move from left to right across a period. Therefore, option (1) - Metallic nature with increase in atomic number is incorrect.

Analyze Trend in Electronegativity and Metallic Character

Electronegativity would only increase if metallic character decreases. Since the statement says 'with increase in metallic character,' this means electronegativity should decrease with an increase in metallic character, making option (2) incorrect.

Analyze Trend in Electronegativity and Atomic Number

As atomic number increases within the same period, electronegativity also increases. Therefore, option (3) - Electronegativity with increase in atomic number is correct.

Analyze Trend in Electropositivity and Atomic Number

Electropositivity decreases as you move from left to right across a period. Hence, option (4) - Electropositivity with increase in atomic number is incorrect.

Key concepts

Metallic Nature

When we talk about metallic nature, we refer to an element's ability to lose electrons and form positive ions (cations). This property is strongly associated with metals, which are typically found on the left-hand side of the periodic table.

As you move from left to right across a period, metallic nature decreases. This happens because atoms increasingly prefer to gain electrons rather than lose them. For instance:

• Sodium (left side) is highly metallic.
• Chlorine (right side) is not metallic at all.

This trend is essential for understanding why option (1) in the exercise is incorrect.

Electronegativity

Electronegativity is a measure of an atom's ability to attract and hold onto electrons. This property varies across the periodic table in a well-defined manner.

As you move from left to right across a period, electronegativity increases. Why? Because the atoms have more protons in the nucleus, attracting electrons more strongly.

Understanding these trends helps grasp why option (3) in the exercise is correct:

• Fluorine, towards the right end of a period, is highly electronegative.
• Sodium, towards the left, is far less so.

Electropositivity

Electropositivity is essentially the opposite of electronegativity. It measures an element's ability to lose electrons and form positive ions.

As you move from left to right across a period, electropositivity decreases. This makes sense because the atoms increasingly prefer to gain electrons rather than lose them.

Example:

• Sodium (left side), very electropositive.
• Fluorine (right side), not electropositive at all.

This trend clarifies why option (4) in the exercise is incorrect.

Atomic Number

The atomic number is fundamental to understanding periodic table trends. It denotes the number of protons in an atom's nucleus and essentially defines the element.

As you move across a period from left to right, the atomic number increases incrementally by 1 for each element. This increase in atomic number affects trends like:

• Electronegativity
• Metallic Nature
• Electropositivity

This consistent increase is why understanding atomic number is critical for grasping periodic table behavior.