Question

levels
circle the larger atom in each pair.
a. k or na b. f or be c. br or v
d. mg or cl e. he or kr f. cs or at
... of full valence electron

Explanation:

To determine the larger atom in each pair, we use the periodic trends of atomic size:

• Atomic size generally increases down a group (due to more electron shells) and decreases across a period (due to increased nuclear charge pulling electrons closer).

Step1: Analyze K or Na

K and Na are in the same group (Group 1). K is below Na, so K has more electron shells.
Larger atom: K

Step2: Analyze F or Be

F and Be are in the same period (Period 2). Be is to the left of F. Atomic size decreases across a period, so Be is larger.
Larger atom: Be

Step3: Analyze Br or V

Br is a non - metal in Group 17, Period 4. V is a metal in Group 5, Period 4. Across a period, atomic size decreases from left to right. V is to the left of Br, so V has a larger atomic radius.
Larger atom: V

Step4: Analyze Mg or Cl

Mg and Cl are in the same period (Period 3). Mg is to the left of Cl. Atomic size decreases across a period, so Mg is larger.
Larger atom: Mg

Step5: Analyze He or Kr

He and Kr are in the same group (Group 18). Kr is below He, so Kr has more electron shells.
Larger atom: Kr

Step6: Analyze Cs or At

Cs is in Group 1, Period 6. At is in Group 17, Period 6. Across a period, atomic size decreases from left to right. Cs is to the left of At, so Cs is larger.
Larger atom: Cs

Answer:

a. K
b. Be
c. V
d. Mg
e. Kr
f. Cs