Question

1. complete the table.

	atomic size	ionization energy	electronegativity
period trend
group trend
rank the following elements by increasing trend: c al o k

Explanation:

• Atomic Size:
• Definition: The distance from the nucleus to the out - most electron shell of an atom.
• Period trend: Decreases across a period (left to right) as the effective nuclear charge increases and pulls the electrons closer.
• Group trend: Increases down a group as the number of electron shells increases.
• Rank for C, Al, O, K: K > Al > C > O (K has the most electron shells, then Al, C and O are in the same period with O having the highest effective nuclear charge among them).
• Ionization Energy:
• Definition: The energy required to remove the outermost electron from a gaseous atom or ion.
• Period trend: Increases across a period (left to right) due to increasing effective nuclear charge and decreasing atomic size.
• Group trend: Decreases down a group as the outermost electrons are farther from the nucleus and easier to remove.
• Rank for C, Al, O, K: K < Al < C < O (K has the lowest ionization energy as it is easiest to remove an electron, and O has the highest among them).
• Electronegativity:
• Definition: The ability of an atom to attract electrons towards itself in a chemical bond.
• Period trend: Increases across a period (left to right) as the effective nuclear charge increases.
• Group trend: Decreases down a group as the atomic size increases and the ability to attract electrons decreases.
• Rank for C, Al, O, K: K < Al < C < O (O is highly electronegative, K is the least among them).

Answer:

	Atomic Size	Ionization Energy	Electronegativity
Period trend	Decreases across a period (left to right)	Increases across a period (left to right)	Increases across a period (left to right)
Group Trend	Increases down a group	Decreases down a group	Decreases down a group
Rank the following elements by increasing trend: C, Al, O, K	K > Al > C > O	K < Al < C < O	K < Al < C < O