Question

explain why atomic size decreases across a period from left to right. *
your answer

fluorine is the most electronegative element. *
true
false

which of the following elements has the largest atomic radius? *
li
c
f
o

Explanation:

• Atomic size decrease across a period: As we move from left to right across a period in the periodic table, the number of protons in the nucleus increases. This leads to a greater positive charge in the nucleus. The electrons are added to the same outermost shell. The increased nuclear charge pulls the electrons closer to the nucleus, resulting in a decrease in atomic size.
• Fluorine electronegativity: Electronegativity is the ability of an atom to attract electrons towards itself in a chemical bond. Fluorine has a small atomic size and a high nuclear charge. Its valence shell is close to the nucleus, and it has a strong tendency to gain an electron to complete its octet. So, it is the most electronegative element.
• Atomic radius comparison (Li, C, F, O): Atomic radius decreases across a period. Lithium (Li) is in group 1, carbon (C) in group 14, oxygen (O) in group 16, and fluorine (F) in group 17 of the same period (period 2). As we move from left (Li) to right (F) in the period, the atomic radius decreases. So, Li has the largest atomic radius among the given elements.

Answer:

• For "Explain why atomic size decreases across a period from left to right": As we move left - to - right across a period, nuclear charge increases while electrons are added to the same shell. The increased nuclear charge pulls electrons closer, reducing atomic size.
• For "Fluorine is the most electronegative element": True.
• For "Which of the following elements has the largest atomic radius?": Li.