Q: Arrange the following elements in order of increasing atomic radius: $\mathrm{O}$, $\mathrm{S}$, $\mathrm{Se}$.

$\mathrm{O} < \mathrm{S} < \mathrm{Se}$

Q: Why does atomic radius decrease as you move from left to right across a period?

The number of protons increases, pulling electrons closer to the nucleus.

Q: A scientist is comparing the atomic radii of $\mathrm{Cl}$ and $\mathrm{Ar}$. Which statement is correct?

$\mathrm{Cl}$ has a larger atomic radius because it has fewer protons.

Q: Which of the following correctly arranges the elements $\mathrm{Na}$, $\mathrm{K}$, $\mathrm{Rb}$ in order of decreasing atomic radius?

$\mathrm{Rb} > \mathrm{K} > \mathrm{Na}$

Question 1

Which of the following statements best explains why atomic radius increases as you move down a group in the periodic table?

Accepted Answer

The number of electron shells increases, causing the outer electrons to be farther from the nucleus.

Question 2

Which element would you expect to have the smallest atomic radius based on its position in the periodic table?

Accepted Answer

Li

Question 3

Arrange the following elements in order of increasing atomic radius: $\mathrm{O}$, $\mathrm{S}$, $\mathrm{Se}$.

Accepted Answer

$\mathrm{O} < \mathrm{S} < \mathrm{Se}$

Question 4

Which of the following alkaline earth metals has the largest atomic radius?

Accepted Answer

Ba

Question 5

Why does atomic radius decrease as you move from left to right across a period?

Accepted Answer

The number of protons increases, pulling electrons closer to the nucleus.

Question 6

Which of the following atoms has the largest atomic radius: $\mathrm{K}$, $\mathrm{Na}$, $\mathrm{Li}$, $\mathrm{Cs}$?

Accepted Answer

$\mathrm{Cs}$

Question 7

A scientist is comparing the atomic radii of $\mathrm{Cl}$ and $\mathrm{Ar}$. Which statement is correct?

Accepted Answer

$\mathrm{Cl}$ has a larger atomic radius because it has fewer protons.

Question 8

Which of the following correctly arranges the elements $\mathrm{Na}$, $\mathrm{K}$, $\mathrm{Rb}$ in order of decreasing atomic radius?

Accepted Answer

$\mathrm{Rb} > \mathrm{K} > \mathrm{Na}$

Question 9

Which of the following elements would you expect to have the smallest atomic radius: $\mathrm{Mg}$, $\mathrm{Ca}$, $\mathrm{Sr}$, $\mathrm{Ba}$?

Accepted Answer

$\mathrm{Mg}$

Question 10

A patient is exposed to a new element with a very large atomic radius. Based on periodic trends, which group is this element most likely to belong to?

Accepted Answer

Alkali metals

Question 11

Which of the following best describes the trend in atomic radius across a period from left to right?

Accepted Answer

Atomic radius decreases due to increased nuclear charge.

Question 12

Which of the following elements would have the largest atomic radius: $\mathrm{F}$, $\mathrm{Cl}$, $\mathrm{Br}$, $\mathrm{I}$?

Accepted Answer

$\mathrm{I}$

Question 13

If you move from $\mathrm{Na}$ to $\mathrm{Cl}$ across a period, what happens to the atomic radius and why?

Accepted Answer

It decreases because the nuclear charge increases, pulling electrons closer.

Question 14

Which of the following is the best explanation for why transition metals have less predictable atomic radii?

Accepted Answer

Their electron arrangements are more complex due to filling of d-orbitals.

Question 15

Arrange the following atoms in order of decreasing atomic radius: $\mathrm{S}$, $\mathrm{Se}$, $\mathrm{Na}$, $\mathrm{Ga}$.

Accepted Answer

$\mathrm{Na} > \mathrm{Se} > \mathrm{Ga} > \mathrm{S}$

Atomic Radius and Periodic Trends

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