Atomic Structure Practice Questions
IB (International Baccalaureate) · IB Chemistry HL · 126 free MCQs with instant results and detailed explanations.
126
Total
33
Easy
60
Medium
33
Hard
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Sample Questions from Atomic Structure
Here are 10 sample questions. Start a quiz to get randomized questions with scoring.
Q1
Easy
What is the maximum number of electrons that can occupy the third principal energy level?
A.
8
B.
18
C.
32
D.
2
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Correct Answer: B
The third principal energy level (n=3) can hold a maximum of 18 electrons, calculated using the formula 2nยฒ, where n is the principal quantum number.
Q2
Easy
Which of the following statements best describes isotopes?
A.
Isotopes have the same number of protons but different numbers of neutrons.
B.
Isotopes have different numbers of protons and electrons.
C.
Isotopes are atoms with the same atomic mass.
D.
Isotopes chemically behave differently due to different electron configurations.
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Correct Answer: A
Isotopes are defined as atoms of the same element that have the same number of protons but different numbers of neutrons, leading to different atomic masses.
Q3
Easy
The electron configuration of an atom is 1sยฒ 2sยฒ 2pโถ 3sยฒ 3pโถ 4sยฒ 3dยนโฐ 4pโต. Which element does this configuration represent?
A.
Bromine (Br)
B.
Chlorine (Cl)
C.
Selenium (Se)
D.
Argon (Ar)
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Correct Answer: A
The given electron configuration corresponds to Bromine (Br), which has 35 electrons. The total number of electrons matches the sum of the subshells provided.
Q4
Medium
Which of the following statements correctly describes the concept of electron configuration?
A.
Electron configuration gives the arrangement of electrons in an atom's nucleus.
B.
Electron configuration describes the distribution of electrons among various orbitals.
C.
Electron configuration is a measure of the energy of electrons in an atom.
D.
Electron configuration determines the atomic number of an element.
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Correct Answer: B
Electron configuration describes how electrons are distributed in an atom's orbitals, indicating their energy levels and arrangements, not their location in the nucleus.
Q5
Medium
An atom of element X has the electron configuration 1sยฒ 2sยฒ 2pโถ 3sยฒ 3pโต. What is the group number of this element in the periodic table?
A.
Group 15
B.
Group 17
C.
Group 16
D.
Group 18
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Correct Answer: B
The electron configuration indicates that element X has 7 electrons in its outermost shell (3sยฒ 3pโต), placing it in Group 17, the halogens.
Q6
Medium
Which of the following elements has the highest ionization energy?
A.
Lithium (Li)
B.
Sodium (Na)
C.
Potassium (K)
D.
Beryllium (Be)
Show Answer & Explanation
Correct Answer: D
Beryllium has the highest ionization energy among the given options due to its smaller atomic radius and higher nuclear charge, which holds electrons more tightly.
Q7
Medium
In the context of atomic structure, what role do neutrons play in an atom?
A.
They determine the chemical properties of the atom.
B.
They contribute to the atomic mass and stabilize the nucleus.
C.
They are involved in the bonding between atoms.
D.
They determine the charge of the atom.
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Correct Answer: B
Neutrons contribute to the atomic mass of an atom and help stabilize the nucleus by offsetting the repulsive forces between positively charged protons.
Q8
Hard
Which of the following statements correctly describes the ground state electron configuration of a neutral atom of phosphorus (atomic number 15)?
A.
1sยฒ 2sยฒ 2pโถ 3sยฒ 3pยณ
B.
1sยฒ 2sยฒ 2pโถ 3sยฒ 3pยฒ 4sยน
C.
1sยฒ 2sยฒ 2pโถ 3sยฒ 3pโด
D.
1sยฒ 2sยฒ 2pโถ 3sยน 3pโต
Show Answer & Explanation
Correct Answer: A
The ground state electron configuration of phosphorus, which has an atomic number of 15, is 1sยฒ 2sยฒ 2pโถ 3sยฒ 3pยณ. This configuration accurately represents the distribution of electrons across the different energy levels and sublevels.
Q9
Hard
Calculate the wavelength of the photon emitted when an electron transitions from the n=3 to n=2 energy level in a hydrogen atom. (Use Rydberg's formula: 1/ฮป = R(1/n1ยฒ - 1/n2ยฒ), where R = 1.097 x 10^7 mโปยน)
A.
6.56 x 10โปโท m
B.
4.86 x 10โปโท m
C.
1.50 x 10โปโท m
D.
3.94 x 10โปโท m
Show Answer & Explanation
Correct Answer: B
For the transition from n=3 to n=2, using Rydberg's formula gives 1/ฮป = 1.097 x 10โท (1/2ยฒ - 1/3ยฒ) = 1.097 x 10โท (1/4 - 1/9) = 1.097 x 10โท * (5/36). Thus, ฮป = 4.86 x 10โปโท m, which corresponds to the transition.
Q10
Hard
Which of the following statements about the electron configuration of transition metals is correct?
A.
Transition metals have partially filled d-orbitals.
B.
Transition metals have only one oxidation state.
C.
All transition metals are paramagnetic due to fully filled d-orbitals.
D.
Transition metals do not form colored compounds.
Show Answer & Explanation
Correct Answer: A
Option A is correct because transition metals are characterized by having one or more d-orbitals that are partially filled, which is crucial for their chemical properties and behaviors. The other options are incorrect as transition metals can have multiple oxidation states, some can be diamagnetic or paramagnetic depending on their electron configuration, and many form colored compounds due to d-d electron transitions.
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Atomic Structure โ IB (International Baccalaureate) IB Chemistry HL Practice Questions Online
This page contains 126 practice MCQs for the chapter Atomic Structure in IB (International Baccalaureate) IB Chemistry HL. The questions are organized by difficulty โ 33 easy, 60 medium, 33 hard โ so you can choose the right level for your preparation.
Every question includes a detailed explanation to help you understand the concept, not just memorize answers. Take a timed quiz to simulate exam conditions, or practice at your own pace with no time limit.