AP Chemistry Flashcards: Atomic Structure And Electron Configuration

What this deck covers

This deck focuses on Atomic Structure And Electron Configuration, giving you a quick way to review the definitions, rules, and examples that matter most for AP Chemistry.

How to use these flashcards

Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: Determine the number of electrons in a magnesium ion (Mg$^{2+}$).

Answer: 10 electrons. Magnesium loses 2 electrons to form $Mg^{2+}$, leaving 10 electrons.

Flashcard 2: What is the formula for calculating the number of neutrons?

Answer: Neutrons = Mass number - Atomic number. Mass number includes both protons and neutrons, so subtract protons to get neutrons.

Flashcard 3: Identify the quantum number that describes the shape of an orbital.

Answer: Azimuthal quantum number ($l$). The $l$ value determines whether an orbital is s, p, d, or f type.

Flashcard 4: What is the spin quantum number ($m_s$) possible values?

Answer: $+\frac{1}{2}$ or $-\frac{1}{2}$. Represents the two possible spin orientations of an electron.

Flashcard 5: State the element with electron configuration $[Ne] 3s^2 3p^5$.

Answer: Chlorine (Cl). The configuration $[Ne] 3s^2 3p^5$ indicates 17 total electrons, which is chlorine.

Flashcard 6: Identify the charge of a neutron.

Answer: Neutral charge (0). Neutrons are electrically neutral particles in the nucleus.

Flashcard 7: What is the electron configuration of helium?

Answer: $1s^2$. Helium has 2 electrons, both filling the 1s orbital.

Flashcard 8: How many electrons can the n=2 energy level hold?

Answer: 8 electrons. The $n=2$ level has 2s and 2p subshells: $2 + 6 = 8$ electrons total.

Flashcard 9: What is the maximum number of orbitals in the n=3 energy level?

Answer: 9 orbitals. The $n=3$ level has s, p, and d subshells: $1 + 3 + 5 = 9$ orbitals.

Flashcard 10: What is the maximum number of orbitals in the n=3 energy level?

Answer: 9 orbitals. The $n=3$ level has s, p, and d subshells: $1 + 3 + 5 = 9$ orbitals.

Flashcard 11: State the element with electron configuration $[Ne] 3s^2 3p^5$.

Answer: Chlorine (Cl). The configuration $[Ne] 3s^2 3p^5$ indicates 17 total electrons, which is chlorine.

Flashcard 12: What is the electron configuration of argon?

Answer: $1s^2 2s^2 2p^6 3s^2 3p^6$. Argon has 18 electrons completely filling through the 3p subshell.

Flashcard 13: What is the electron configuration of an oxygen ion (O$^{2-}$)?

Answer: $1s^2 2s^2 2p^6$. Oxide ion gains 2 electrons, achieving neon's electron configuration.

Flashcard 14: What does the magnetic quantum number ($m_l$) indicate?

Answer: Orientation of an orbital. Describes which specific orbital within a subshell the electron occupies.

Flashcard 15: Identify the quantum number that describes the shape of an orbital.

Answer: Azimuthal quantum number ($l$). The $l$ value determines whether an orbital is s, p, d, or f type.

Flashcard 16: State the maximum number of electrons in the n=4 energy level.

Answer: 32 electrons. The $n=4$ level can hold $2n^2 = 2(4)^2 = 32$ electrons total.

Flashcard 17: What is the electron configuration of helium?

Answer: $1s^2$. Helium has 2 electrons, both filling the 1s orbital.

Flashcard 18: Identify the number of unpaired electrons in a carbon atom.

Answer: 2 unpaired electrons. Carbon's 2p subshell has 2 electrons, both unpaired by Hund's rule.

Flashcard 19: What is the electron configuration notation for neon?

Answer: $1s^2 2s^2 2p^6$. Neon has 10 electrons filling through the 2p subshell completely.

Flashcard 20: What is the maximum number of orbitals in the n=3 energy level?

Answer: 9 orbitals. The $n=3$ level has s, p, and d subshells: $1 + 3 + 5 = 9$ orbitals.

Flashcard 21: What does the magnetic quantum number ($m_l$) indicate?

Answer: Orientation of an orbital. Describes which specific orbital within a subshell the electron occupies.

Flashcard 22: State the element with electron configuration $[Ne] 3s^2 3p^5$.

Answer: Chlorine (Cl). The configuration $[Ne] 3s^2 3p^5$ indicates 17 total electrons, which is chlorine.

Flashcard 23: What is the electron configuration for sulfur?

Answer: $1s^2 2s^2 2p^6 3s^2 3p^4$. Sulfur has 16 electrons, with 4 electrons in the 3p subshell.

Flashcard 24: What is the electron configuration of an oxygen ion (O$^{2-}$)?

Answer: $1s^2 2s^2 2p^6$. Oxide ion gains 2 electrons, achieving neon's electron configuration.

Flashcard 25: What is the formula for calculating the number of neutrons?

Answer: Neutrons = Mass number - Atomic number. Mass number includes both protons and neutrons, so subtract protons to get neutrons.

Flashcard 26: Find the total number of electrons in a neon atom.

Answer: 10 electrons. Neon's atomic number is 10, so neutral atoms have 10 electrons.

Flashcard 27: What is the azimuthal quantum number for p orbitals?

Answer: $l = 1$. P orbitals correspond to $l = 1$ in the azimuthal quantum number system.

Flashcard 28: Determine the electron configuration for sodium.

Answer: $1s^2 2s^2 2p^6 3s^1$. Sodium has 11 electrons, filling through 3s with one electron.

Flashcard 29: What is the electron configuration of potassium?

Answer: $1s^2 2s^2 2p^6 3s^2 3p^6 4s^1$. Potassium has 19 electrons, with the last electron in the 4s orbital.

Flashcard 30: What is the electron configuration of argon?

Answer: $1s^2 2s^2 2p^6 3s^2 3p^6$. Argon has 18 electrons completely filling through the 3p subshell.

Flashcard 31: What is the electron configuration for a fluoride ion (F-)?

Answer: $1s^2 2s^2 2p^6$. Fluoride ion gains one electron, achieving neon's electron configuration.

Flashcard 32: What does the Aufbau principle describe?

Answer: Electron filling order in orbitals. Electrons fill lowest energy orbitals first before higher energy ones.

Flashcard 33: State the maximum number of electrons in the n=4 energy level.

Answer: 32 electrons. The $n=4$ level can hold $2n^2 = 2(4)^2 = 32$ electrons total.

Flashcard 34: How many electrons can the n=2 energy level hold?

Answer: 8 electrons. The $n=2$ level has 2s and 2p subshells: $2 + 6 = 8$ electrons total.

Flashcard 35: What is the electron configuration for a fluoride ion (F-)?

Answer: $1s^2 2s^2 2p^6$. Fluoride ion gains one electron, achieving neon's electron configuration.

Flashcard 36: What is the principal quantum number symbolized by?

Answer: n. The principal quantum number indicates the energy level or shell.

Flashcard 37: Which principle states that no two electrons can have the same set of quantum numbers?

Answer: Pauli Exclusion Principle. Each electron must have a unique set of four quantum numbers.

Flashcard 38: Identify the number of orbitals in a d subshell.

Answer: 5 orbitals. The d subshell contains 5 degenerate orbitals.

Flashcard 39: What is the electron configuration notation for neon?

Answer: $1s^2 2s^2 2p^6$. Neon has 10 electrons filling through the 2p subshell completely.

Flashcard 40: What is the electron configuration of carbon?

Answer: $1s^2 2s^2 2p^2$. Carbon has 6 electrons: 2 in 1s, 2 in 2s, and 2 in 2p.

Flashcard 41: What is the electron configuration notation for neon?

Answer: $1s^2 2s^2 2p^6$. Neon has 10 electrons filling through the 2p subshell completely.

Flashcard 42: What is the atomic number of an element?

Answer: The number of protons in the nucleus. Defines the element's identity and equals the number of electrons in neutral atoms.

Flashcard 43: What is the electron configuration of helium?

Answer: $1s^2$. Helium has 2 electrons, both filling the 1s orbital.

Flashcard 44: Identify the quantum number that describes the shape of an orbital.

Answer: Azimuthal quantum number ($l$). The $l$ value determines whether an orbital is s, p, d, or f type.

Flashcard 45: Determine the number of electrons in a magnesium ion (Mg$^{2+}$).

Answer: 10 electrons. Magnesium loses 2 electrons to form $Mg^{2+}$, leaving 10 electrons.

Flashcard 46: What is the electron configuration for sulfur?

Answer: $1s^2 2s^2 2p^6 3s^2 3p^4$. Sulfur has 16 electrons, with 4 electrons in the 3p subshell.

Flashcard 47: Identify the maximum number of electrons in an f subshell.

Answer: 14 electrons. The f subshell has 7 orbitals, each holding 2 electrons maximum.

Flashcard 48: Identify the number of orbitals in a d subshell.

Answer: 5 orbitals. The d subshell contains 5 degenerate orbitals.

Flashcard 49: What is the shape of an s orbital?

Answer: Spherical. All s orbitals have spherical symmetry around the nucleus.

Flashcard 50: What does the magnetic quantum number ($m_l$) indicate?

Answer: Orientation of an orbital. Describes which specific orbital within a subshell the electron occupies.

Flashcard 51: What is the atomic number of an element?

Answer: The number of protons in the nucleus. Defines the element's identity and equals the number of electrons in neutral atoms.

Flashcard 52: What is the electron configuration of carbon?

Answer: $1s^2 2s^2 2p^2$. Carbon has 6 electrons: 2 in 1s, 2 in 2s, and 2 in 2p.

Flashcard 53: State the number of valence electrons in oxygen.

Answer: 6 valence electrons. Oxygen is in group 16, so it has 6 electrons in its outermost shell.

Flashcard 54: Which principle states that no two electrons can have the same set of quantum numbers?

Answer: Pauli Exclusion Principle. Each electron must have a unique set of four quantum numbers.

Flashcard 55: State the value range for the azimuthal quantum number ($l$).

Answer: 0 to $n-1$. For a given $n$, the azimuthal quantum number ranges from 0 to $n-1$.

Flashcard 56: State the element with the electron configuration $[Xe] 6s^2 4f^{14} 5d^{10} 6p^2$.

Answer: Lead (Pb). The configuration ends in $6p^2$, characteristic of lead in group 14.

Flashcard 57: Identify the charge of a neutron.

Answer: Neutral charge (0). Neutrons are electrically neutral particles in the nucleus.

Flashcard 58: Identify the number of valence electrons in nitrogen.

Answer: 5 valence electrons. Nitrogen is in group 15, so it has 5 valence electrons.

Flashcard 59: What is the spin quantum number ($m_s$) possible values?

Answer: $+\frac{1}{2}$ or $-\frac{1}{2}$. Represents the two possible spin orientations of an electron.

Flashcard 60: State the number of valence electrons in oxygen.

Answer: 6 valence electrons. Oxygen is in group 16, so it has 6 electrons in its outermost shell.

Flashcard 61: Find the number of electrons in a neutral chlorine atom.

Answer: 17 electrons. Chlorine's atomic number is 17, so neutral atoms have 17 electrons.

Flashcard 62: What is the electron configuration of a calcium ion (Ca$^{2+}$)?

Answer: $1s^2 2s^2 2p^6 3s^2 3p^6$. Calcium loses 2 electrons to form $Ca^{2+}$, giving argon's configuration.

Flashcard 63: Identify the number of unpaired electrons in a carbon atom.

Answer: 2 unpaired electrons. Carbon's 2p subshell has 2 electrons, both unpaired by Hund's rule.

Flashcard 64: Find the number of electrons in a neutral chlorine atom.

Answer: 17 electrons. Chlorine's atomic number is 17, so neutral atoms have 17 electrons.

Flashcard 65: Determine the electron configuration for sodium.

Answer: $1s^2 2s^2 2p^6 3s^1$. Sodium has 11 electrons, filling through 3s with one electron.

Flashcard 66: Identify the charge of a neutron.

Answer: Neutral charge (0). Neutrons are electrically neutral particles in the nucleus.

Flashcard 67: What is the azimuthal quantum number for p orbitals?

Answer: $l = 1$. P orbitals correspond to $l = 1$ in the azimuthal quantum number system.

Flashcard 68: What is the electron configuration of argon?

Answer: $1s^2 2s^2 2p^6 3s^2 3p^6$. Argon has 18 electrons completely filling through the 3p subshell.

Flashcard 69: Determine the number of electrons in a magnesium ion ($Mg^{2+}$).

Answer: 10 electrons. Magnesium loses 2 electrons to form $Mg^{2+}$, leaving 10 electrons.

Flashcard 70: Determine the number of unpaired electrons in oxygen.

Answer: 2 unpaired electrons. Oxygen's 2p subshell has 4 electrons: 2 paired and 2 unpaired by Hund's rule.

Flashcard 71: State the value range for the azimuthal quantum number ($l$).

Answer: 0 to $n-1$. For a given $n$, the azimuthal quantum number ranges from 0 to $n-1$.

Flashcard 72: Identify the maximum number of electrons in an f subshell.

Answer: 14 electrons. The f subshell has 7 orbitals, each holding 2 electrons maximum.

Flashcard 73: State the element with the electron configuration $[Xe] 6s^2 4f^{14} 5d^{10} 6p^2$.

Answer: Lead (Pb). The configuration ends in $6p^2$, characteristic of lead in group 14.

Flashcard 74: State the maximum number of electrons in the n=4 energy level.

Answer: 32 electrons. The $n=4$ level can hold $2n^2 = 2(4)^2 = 32$ electrons total.

Flashcard 75: Identify the number of valence electrons in nitrogen.

Answer: 5 valence electrons. Nitrogen is in group 15, so it has 5 valence electrons.

Flashcard 76: Find the number of electrons in a neutral chlorine atom.

Answer: 17 electrons. Chlorine's atomic number is 17, so neutral atoms have 17 electrons.

Flashcard 77: Determine the number of unpaired electrons in oxygen.

Answer: 2 unpaired electrons. Oxygen's 2p subshell has 4 electrons: 2 paired and 2 unpaired by Hund's rule.

Flashcard 78: What is the electron configuration for aluminum?

Answer: $1s^2 2s^2 2p^6 3s^2 3p^1$. Aluminum has 13 electrons, with 1 electron in the 3p subshell.

Flashcard 79: What is the electron configuration of a calcium ion (Ca$^{2+}$)?

Answer: $1s^2 2s^2 2p^6 3s^2 3p^6$. Calcium loses 2 electrons to form $Ca^{2+}$, giving argon's configuration.

Flashcard 80: What is the electron configuration of a calcium ion (Ca$^{2+}$)?

Answer: $1s^2 2s^2 2p^6 3s^2 3p^6$. Calcium loses 2 electrons to form $Ca^{2+}$, giving argon's configuration.

Flashcard 81: Determine the number of electrons in a magnesium ion (Mg$^{2+}$).

Answer: 10 electrons. Magnesium loses 2 electrons to form $Mg^{2+}$, leaving 10 electrons.

Flashcard 82: What is the principal quantum number symbolized by?

Answer: n. The principal quantum number indicates the energy level or shell.

Flashcard 83: Identify the number of valence electrons in nitrogen.

Answer: 5 valence electrons. Nitrogen is in group 15, so it has 5 valence electrons.

Flashcard 84: What is the shape of an s orbital?

Answer: Spherical. All s orbitals have spherical symmetry around the nucleus.

Flashcard 85: Which principle states that no two electrons can have the same set of quantum numbers?

Answer: Pauli Exclusion Principle. Each electron must have a unique set of four quantum numbers.

Flashcard 86: What is the electron configuration of an oxygen ion (O$^{2-}$)?

Answer: $1s^2 2s^2 2p^6$. Oxide ion gains 2 electrons, achieving neon's electron configuration.

Flashcard 87: What is the atomic number of an element?

Answer: The number of protons in the nucleus. Defines the element's identity and equals the number of electrons in neutral atoms.

Flashcard 88: How many electrons can the n=2 energy level hold?

Answer: 8 electrons. The $n=2$ level has 2s and 2p subshells: $2 + 6 = 8$ electrons total.

Flashcard 89: How many electrons can occupy a single orbital?

Answer: 2 electrons. Maximum capacity per orbital due to Pauli Exclusion Principle.

Flashcard 90: What is the electron configuration for sulfur?

Answer: $1s^2 2s^2 2p^6 3s^2 3p^4$. Sulfur has 16 electrons, with 4 electrons in the 3p subshell.

Flashcard 91: What is the electron configuration of potassium?

Answer: $1s^2 2s^2 2p^6 3s^2 3p^6 4s^1$. Potassium has 19 electrons, with the last electron in the 4s orbital.

Flashcard 92: State the value range for the azimuthal quantum number ($l$).

Answer: 0 to $n-1$. For a given $n$, the azimuthal quantum number ranges from 0 to $n-1$.

Flashcard 93: State the element with the electron configuration $[Xe] 6s^2 4f^{14} 5d^{10} 6p^2$.

Answer: Lead (Pb). The configuration ends in $6p^2$, characteristic of lead in group 14.

Flashcard 94: What is the principal quantum number symbolized by?

Answer: n. The principal quantum number indicates the energy level or shell.

Flashcard 95: Identify the number of unpaired electrons in a carbon atom.

Answer: 2 unpaired electrons. Carbon's 2p subshell has 2 electrons, both unpaired by Hund's rule.

Flashcard 96: Find the total number of electrons in a neon atom.

Answer: 10 electrons. Neon's atomic number is 10, so neutral atoms have 10 electrons.

Flashcard 97: What does the Aufbau principle describe?

Answer: Electron filling order in orbitals. Electrons fill lowest energy orbitals first before higher energy ones.

Flashcard 98: What is the electron configuration of carbon?

Answer: $1s^2 2s^2 2p^2$. Carbon has 6 electrons: 2 in 1s, 2 in 2s, and 2 in 2p.

Flashcard 99: Which rule states that electrons fill degenerate orbitals singly first?

Answer: Hund's Rule. Maximizes unpaired electrons before pairing to minimize electron-electron repulsion.

Flashcard 100: What is the electron configuration of potassium?

Answer: $1s^2 2s^2 2p^6 3s^2 3p^6 4s^1$. Potassium has 19 electrons, with the last electron in the 4s orbital.