Question

1. which of the following pairs of elements have

the lower electronegativity?
k or li
br or co
n or as
f or c

Explanation:

To determine which element in each pair has lower electronegativity, we use the trends of electronegativity in the periodic table:

• Electronegativity generally increases across a period (left to right) and decreases down a group (top to bottom).

Pair 1: K or Li

• K (Potassium) and Li (Lithium) are in Group 1 (alkali metals).
• Electronegativity decreases down a group. K is below Li in Group 1.
• Thus, K has lower electronegativity.

Pair 2: Br or Co

• Br (Bromine) is in Group 17 (halogens), Period 4.
• Co (Cobalt) is in Group 9, Period 4 (transition metal).
• Across a period, electronegativity increases from left to right. Co is to the left of Br in Period 4.
• Thus, Co has lower electronegativity.

Pair 3: N or As

• N (Nitrogen) is in Group 15, Period 2.
• As (Arsenic) is in Group 15, Period 4.
• Electronegativity decreases down a group. As is below N in Group 15.
• Thus, As has lower electronegativity.

Pair 4: F or C

• F (Fluorine) is in Group 17, Period 2.
• C (Carbon) is in Group 14, Period 2.
• Across a period, electronegativity increases from left to right. C is to the left of F in Period 2.
• Thus, C has lower electronegativity.

Final Answers:

• K or Li: $\boldsymbol{\text{K}}$
• Br or Co: $\boldsymbol{\text{Co}}$
• N or As: $\boldsymbol{\text{As}}$
• F or C: $\boldsymbol{\text{C}}$

Answer:

To determine which element in each pair has lower electronegativity, we use the trends of electronegativity in the periodic table:

• Electronegativity generally increases across a period (left to right) and decreases down a group (top to bottom).

Pair 1: K or Li

• K (Potassium) and Li (Lithium) are in Group 1 (alkali metals).
• Electronegativity decreases down a group. K is below Li in Group 1.
• Thus, K has lower electronegativity.

Pair 2: Br or Co

• Br (Bromine) is in Group 17 (halogens), Period 4.
• Co (Cobalt) is in Group 9, Period 4 (transition metal).
• Across a period, electronegativity increases from left to right. Co is to the left of Br in Period 4.
• Thus, Co has lower electronegativity.

Pair 3: N or As

• N (Nitrogen) is in Group 15, Period 2.
• As (Arsenic) is in Group 15, Period 4.
• Electronegativity decreases down a group. As is below N in Group 15.
• Thus, As has lower electronegativity.

Pair 4: F or C

• F (Fluorine) is in Group 17, Period 2.
• C (Carbon) is in Group 14, Period 2.
• Across a period, electronegativity increases from left to right. C is to the left of F in Period 2.
• Thus, C has lower electronegativity.

Final Answers:

• K or Li: $\boldsymbol{\text{K}}$
• Br or Co: $\boldsymbol{\text{Co}}$
• N or As: $\boldsymbol{\text{As}}$
• F or C: $\boldsymbol{\text{C}}$