Question 1

Which of the following statements best describes the Bohr model of the atom?

Accepted Answer

Electrons move in fixed orbits around the nucleus, with each orbit corresponding to a specific energy level.

Question 2

Which of the following correctly explains the trend in ionization energy across a period in the periodic table?

Accepted Answer

Ionization energy increases across a period due to increasing nuclear charge, which holds electrons more tightly.

Question 3

A sodium atom ($Na$) loses one electron to form a $Na^+$ ion. Which statement best explains the change in its electron configuration?

Accepted Answer

The $Na^+$ ion has the same electron configuration as neon ($Ne$), a noble gas.

Question 4

Which of the following elements has the largest atomic radius?

Accepted Answer

Potassium ($K$)

Question 5

Which of the following best describes the relationship between valence electrons and chemical reactivity for Group 1 elements?

Accepted Answer

Group 1 elements have one valence electron, making them highly reactive as they tend to lose this electron easily.

Question 6

Which of the following ions is isoelectronic with neon ($Ne$)?

Accepted Answer

$F^-$

Question 7

Given the electron configuration $1s^2 2s^2 2p^6 3s^2 3p^4$, which element does this represent?

Accepted Answer

Sulfur ($S$)

Question 8

Which of the following best explains why the atomic radius decreases across a period from left to right?

Accepted Answer

The increasing nuclear charge pulls electrons closer to the nucleus, reducing atomic size.

Question 9

Which of the following is the correct shorthand electron configuration for calcium ($Ca$)?

Accepted Answer

$[Ar] 4s^2$

Question 10

A chlorine atom gains one electron to form a $Cl^-$ ion. What is the resulting electron configuration?

Accepted Answer

$1s^2 2s^2 2p^6 3s^2 3p^6$

Question 11

Which of the following best describes the trend in atomic radius down a group in the periodic table?

Accepted Answer

Atomic radius increases due to the addition of energy levels.

Question 12

Which of the following elements has the highest first ionization energy?

Accepted Answer

Fluorine ($F$)

Question 13

Which of the following statements about electron configuration is correct?

Accepted Answer

Electrons fill the lowest available energy levels first, according to the Aufbau principle.

Question 14

Which of the following best explains why noble gases are generally unreactive?

Accepted Answer

They have a full valence shell, making them stable and unlikely to gain or lose electrons.

Question 15

Which of the following ions has the same number of electrons as a neutral magnesium atom ($Mg$)?

Accepted Answer

$Al^+$

Question 16

Which of the following best describes the process of ionization energy?

Accepted Answer

The energy required to remove an electron from a gaseous atom.

Question 17

Which of the following is the correct electron configuration for a $N^{3-}$ ion?

Accepted Answer

$1s^2 2s^2 2p^6$

Question 18

Which of the following best explains why $Mg^{2+}$ is more stable than $Mg^+$?

Accepted Answer

$Mg^{2+}$ has a full octet in its outermost shell, making it more stable.

Question 19

Which of the following is the correct order of increasing atomic radius for the elements $O$, $F$, and $N$?

Accepted Answer

$F < O < N$

Question 20

A patient is found to have a high concentration of $K^+$ ions in their blood. Which of the following statements about the $K^+$ ion is correct?

Accepted Answer

$K^+$ has lost one electron compared to a neutral potassium atom, resulting in a noble gas electron configuration.

Atomic Structure, Periodic Trends, and Electron Configuration Study Notes

Study Guide - Practice Questions