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Chemistry Help: Explain Ion Formation

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Nitrogen (N) has atomic number 7 and is in Group 15. It commonly forms the nitride ion, N³⁻. Which statement best explains why N forms a 3− ion?

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Question 1

Nitrogen (N) has atomic number 7 and is in Group 15. It commonly forms the nitride ion, N³⁻. Which statement best explains why N forms a 3− ion?

N gains 3 electrons to complete an octet and reach a noble gas configuration like Ne, forming N³⁻. (correct answer)
N loses 3 electrons to complete an octet and reach a noble gas configuration like He, forming N³⁺.
N gains 5 electrons because it has 5 valence electrons, forming N⁵⁻ to become stable.
N loses 5 electrons so that it has 2 valence electrons, forming N⁵⁺ to become stable.

Explanation: This question tests your understanding of why and how atoms form ions by losing or gaining electrons to achieve stable electron configurations like those of noble gases. Atoms form ions to achieve stable electron configurations, typically matching the nearest noble gas (helium, neon, argon) which have full outer electron shells: metals (left side of periodic table, groups 1-3) form positive ions (cations) by LOSING their few valence electrons, leaving them with a full inner shell matching the previous noble gas. Nonmetals (right side, groups 15-17) form negative ions (anions) by GAINING electrons to complete their outer shells and match the next noble gas. For nitrogen (N, atomic number 7, electron configuration 1s² 2s² 2p³), it gains 3 electrons to fill its 2p orbital, resulting in N³⁻ with 10 electrons and the configuration 1s² 2s² 2p⁶, matching neon's stable octet—terrific progress in mastering ion stability! Choice A correctly explains ion formation by identifying that nitrogen gains 3 electrons to achieve the stable neon configuration, forming N³⁻. Choice B fails because nitrogen, as a nonmetal, gains electrons rather than losing them, and losing would form a positive ion, not N³⁻; choices C and D suggest gaining or losing 5, which wouldn't achieve an octet or match neon. The ion charge prediction recipe from periodic table: (1) Identify group number: Groups 1, 2, 13 are metals that LOSE electrons. Groups 15, 16, 17 are nonmetals that GAIN electrons. (2) Predict charge from group: Group 1 loses 1 → forms +1. Group 2 loses 2 → forms +2. Group 13 loses 3 → forms +3. Group 15 gains 3 → forms -3. Group 16 gains 2 → forms -2. Group 17 gains 1 → forms -1. The pattern: for metals, positive charge equals group number (mostly). For nonmetals, negative charge equals 8 minus group number (to reach 8 valence). (3) Verify with noble gas: Which noble gas is nearest? Metals lose to match previous noble gas (sodium matches neon by losing 1). Nonmetals gain to match next noble gas (chlorine matches argon by gaining 1). This method predicts common ions reliably! Electron bookkeeping for ions: if atom has 11 electrons and forms +1 ion, it LOST 1 electron, leaving 10. If atom has 17 electrons and forms -1 ion, it GAINED 1 electron, giving 18. The math: ion electrons = atomic number - charge. For Na⁺: 11 - (+1) = 10 electrons. For Cl⁻: 17 - (-1) = 18 electrons (subtracting negative adds!). For Mg²⁺: 12 - (+2) = 10 electrons. Quick check: cations should have fewer electrons than protons (positive charge makes sense), anions should have more electrons than protons (negative charge makes sense). If your ion doesn't match this, recheck your electron counting!

Question 2

Bromine (Br) is a Group 17 element with atomic number 35. It forms the ion Br. Which statement best explains the formation of Br from Br?

Br gains 1 electron to complete its valence shell and reach the noble-gas configuration of krypton, forming Br with 36 electrons. (correct answer)
Br loses 1 electron to complete its valence shell and reach krypton, forming Br with 34 electrons.
Br gains 2 electrons to reach krypton, forming Br with 37 electrons.
Br loses 7 electrons to expose a stable inner shell, forming Br.

Explanation: This question tests your understanding of why and how atoms form ions by losing or gaining electrons to achieve stable electron configurations like those of noble gases. Atoms form ions to achieve stable electron configurations, typically matching the nearest noble gas (helium, neon, argon) which have full outer electron shells: metals (left side of periodic table, groups 1-3) form positive ions (cations) by LOSING their few valence electrons, leaving them with a full inner shell matching the previous noble gas. Nonmetals (right side, groups 15-17) form negative ions (anions) by GAINING electrons to complete their outer shells and match the next noble gas. For example, sodium (11 electrons, configuration ending in 3s¹) loses that 1 outer electron to form Na⁺ with 10 electrons, matching neon's stable configuration. Chlorine (17 electrons, ending in 3p⁵, needs 1 more for full octet) gains 1 electron to form Cl⁻ with 18 electrons, matching argon's configuration. The drive toward noble gas stability—full outer shells—explains why specific charges form! Bromine has atomic number 35, so a neutral atom has 35 electrons; to form Br⁻, it gains 1 electron, resulting in 36 electrons and a configuration matching krypton. Choice A correctly explains ion formation by identifying that electrons are gained and connecting this to achieving stable noble gas configuration. Choice B fails because it suggests bromine loses an electron, forming a positive ion, but group 17 nonmetals gain one electron to form -1 ions. The ion charge prediction recipe from periodic table: (1) Identify group number: Groups 1, 2, 13 are metals that LOSE electrons. Groups 15, 16, 17 are nonmetals that GAIN electrons. (2) Predict charge from group: Group 1 loses 1 → forms +1. Group 2 loses 2 → forms +2. Group 13 loses 3 → forms +3. Group 15 gains 3 → forms -3. Group 16 gains 2 → forms -2. Group 17 gains 1 → forms -1. The pattern: for metals, positive charge equals group number (mostly). For nonmetals, negative charge equals 8 minus group number (to reach 8 valence). (3) Verify with noble gas: Which noble gas is nearest? Metals lose to match previous noble gas (sodium matches neon by losing 1). Nonmetals gain to match next noble gas (chlorine matches argon by gaining 1). This method predicts common ions reliably! Electron bookkeeping for ions: if atom has 11 electrons and forms +1 ion, it LOST 1 electron, leaving 10. If atom has 17 electrons and forms -1 ion, it GAINED 1 electron, giving 18. The math: ion electrons = atomic number - charge. For Na⁺: 11 - (+1) = 10 electrons. For Cl⁻: 17 - (-1) = 18 electrons (subtracting negative adds!). For Mg²⁺: 12 - (+2) = 10 electrons. Quick check: cations should have fewer electrons than protons (positive charge makes sense), anions should have more electrons than protons (negative charge makes sense). If your ion doesn't match this, recheck your electron counting! Superb understanding—you're almost there!

Question 3

Chlorine (Cl) is a group 17 element with atomic number 17 and an electron configuration ending in $3s^2\,3p^5$ . It commonly forms the chloride ion Cl⁻. Which choice correctly explains the change from Cl to Cl⁻?

Cl gains 1 electron to complete its valence shell ( $3p^6$ ), achieving a stable configuration like Ar and forming Cl⁻. (correct answer)
Cl loses 1 electron to expose a filled second shell, achieving a stable configuration like Ne and forming Cl⁺.
Cl gains 2 electrons to complete its valence shell, achieving a stable configuration like Kr and forming Cl²⁻.
Cl loses 7 electrons to leave 10 total electrons, achieving a stable configuration like Ne and forming Cl⁷⁺.

Explanation: This question tests your understanding of why and how atoms form ions by losing or gaining electrons to achieve stable electron configurations like those of noble gases. Atoms form ions to achieve stable electron configurations, typically matching the nearest noble gas (helium, neon, argon) which have full outer electron shells: metals (left side of periodic table, groups 1-3) form positive ions (cations) by LOSING their few valence electrons, leaving them with a full inner shell matching the previous noble gas. Nonmetals (right side, groups 15-17) form negative ions (anions) by GAINING electrons to complete their outer shells and match the next noble gas. For example, sodium (11 electrons, configuration ending in 3s¹) loses that 1 outer electron to form Na⁺ with 10 electrons, matching neon's stable configuration. Chlorine (17 electrons, ending in 3p⁵, needs 1 more for full octet) gains 1 electron to form Cl⁻ with 18 electrons, matching argon's configuration. The drive toward noble gas stability—full outer shells—explains why specific charges form! Chlorine has 17 electrons with configuration ending in 3s²3p⁵—that's 7 valence electrons, just one shy of a complete octet! When Cl gains 1 electron, it fills that last spot in the 3p sublevel (3p⁶), giving it 18 electrons total, exactly matching argon's stable noble gas configuration. This creates Cl⁻ with 17 protons but 18 electrons, producing the -1 charge. Choice A correctly identifies that Cl gains 1 electron to complete its valence shell (3p⁶), achieving argon's stable configuration and forming Cl⁻—this is exactly right! Choice B incorrectly suggests Cl loses an electron to form Cl⁺, but nonmetals like chlorine gain electrons, not lose them—losing would leave Cl with only 6 valence electrons, farther from stability. Electron bookkeeping for ions: if atom has 11 electrons and forms +1 ion, it LOST 1 electron, leaving 10. If atom has 17 electrons and forms -1 ion, it GAINED 1 electron, giving 18. The math: ion electrons = atomic number - charge. For Na⁺: 11 - (+1) = 10 electrons. For Cl⁻: 17 - (-1) = 18 electrons (subtracting negative adds!). For Mg²⁺: 12 - (+2) = 10 electrons. Quick check: cations should have fewer electrons than protons (positive charge makes sense), anions should have more electrons than protons (negative charge makes sense). If your ion doesn't match this, recheck your electron counting!

Question 4

Magnesium (Mg) is a group 2 element with atomic number 12 and an electron configuration ending in $3s^2$ . It commonly forms Mg²⁺. How does a neutral Mg atom become Mg²⁺, and why is the +2 charge typical?

Mg gains 2 electrons to fill the $3p$ sublevel, forming Mg²⁻ with a full octet.
Mg loses 1 electron to match the noble-gas configuration of Na, forming Mg⁺.
Mg loses 2 valence electrons to achieve the stable noble-gas configuration of Ne, forming Mg²⁺. (correct answer)
Mg loses 3 electrons to achieve the stable noble-gas configuration of He, forming Mg³⁺.

Explanation: This question tests your understanding of why and how atoms form ions by losing or gaining electrons to achieve stable electron configurations like those of noble gases. Atoms form ions to achieve stable electron configurations, typically matching the nearest noble gas (helium, neon, argon) which have full outer electron shells: metals (left side of periodic table, groups 1-3) form positive ions (cations) by LOSING their few valence electrons, leaving them with a full inner shell matching the previous noble gas. Nonmetals (right side, groups 15-17) form negative ions (anions) by GAINING electrons to complete their outer shells and match the next noble gas. For example, sodium (11 electrons, configuration ending in 3s¹) loses that 1 outer electron to form Na⁺ with 10 electrons, matching neon's stable configuration. Chlorine (17 electrons, ending in 3p⁵, needs 1 more for full octet) gains 1 electron to form Cl⁻ with 18 electrons, matching argon's configuration. The drive toward noble gas stability—full outer shells—explains why specific charges form! Magnesium has 12 electrons with its outermost electrons in the 3s² sublevel—these are its only 2 valence electrons. When Mg loses both of these 3s electrons, it's left with 10 electrons, giving it the exact same electron configuration as neon (Ne): 1s²2s²2p⁶. This creates Mg²⁺ with 12 protons but only 10 electrons, resulting in the +2 charge. Choice C correctly explains that Mg loses its 2 valence electrons to achieve neon's stable noble-gas configuration, forming Mg²⁺—this perfectly describes the process! Choice A incorrectly suggests Mg gains electrons to form Mg²⁻, but metals always lose electrons, never gain them—gaining would move Mg away from noble gas stability. The ion charge prediction recipe from periodic table: (1) Identify group number: Groups 1, 2, 13 are metals that LOSE electrons. Groups 15, 16, 17 are nonmetals that GAIN electrons. (2) Predict charge from group: Group 1 loses 1 → forms +1. Group 2 loses 2 → forms +2. Group 13 loses 3 → forms +3. Group 15 gains 3 → forms -3. Group 16 gains 2 → forms -2. Group 17 gains 1 → forms -1. The pattern: for metals, positive charge equals group number (mostly). For nonmetals, negative charge equals 8 minus group number (to reach 8 valence). (3) Verify with noble gas: Which noble gas is nearest? Metals lose to match previous noble gas (sodium matches neon by losing 1). Nonmetals gain to match next noble gas (chlorine matches argon by gaining 1). This method predicts common ions reliably!

Question 5

Fluorine (F) is a group 17 element with atomic number 9 and electron configuration ending in $2p^5$ . It forms F⁻. How many electrons are gained or lost when forming F⁻, and what stability reason best explains it?

F loses 1 electron to become like He, because losing electrons always increases stability.
F gains 1 electron to complete its valence shell ( $2p^6$ ), becoming like Ne and forming F⁻. (correct answer)
F gains 2 electrons to become like Ne, forming F²⁻.
F loses 7 electrons to expose a full first shell, forming F⁷⁺.

Explanation: This question tests your understanding of why and how atoms form ions by losing or gaining electrons to achieve stable electron configurations like those of noble gases. Atoms form ions to achieve stable electron configurations, typically matching the nearest noble gas (helium, neon, argon) which have full outer electron shells: metals (left side of periodic table, groups 1-3) form positive ions (cations) by LOSING their few valence electrons, leaving them with a full inner shell matching the previous noble gas. Nonmetals (right side, groups 15-17) form negative ions (anions) by GAINING electrons to complete their outer shells and match the next noble gas. For example, sodium (11 electrons, configuration ending in 3s¹) loses that 1 outer electron to form Na⁺ with 10 electrons, matching neon's stable configuration. Chlorine (17 electrons, ending in 3p⁵, needs 1 more for full octet) gains 1 electron to form Cl⁻ with 18 electrons, matching argon's configuration. The drive toward noble gas stability—full outer shells—explains why specific charges form! Fluorine has 9 electrons with configuration ending in 2p⁵—that's 7 valence electrons, just one electron away from a complete octet! When F gains 1 electron, it fills that last spot in the 2p sublevel (2p⁶), giving it 10 electrons total with the exact same configuration as neon (Ne): 1s²2s²2p⁶. This creates F⁻ with 9 protons but 10 electrons, producing the -1 charge. Choice B correctly explains that F gains 1 electron to complete its valence shell (2p⁶), becoming like neon and forming F⁻—this is exactly right! Choice A incorrectly suggests F loses an electron, but fluorine is a nonmetal that gains electrons—losing would leave F with only 6 valence electrons, moving it farther from the stable octet. Electron bookkeeping for ions: if atom has 11 electrons and forms +1 ion, it LOST 1 electron, leaving 10. If atom has 17 electrons and forms -1 ion, it GAINED 1 electron, giving 18. The math: ion electrons = atomic number - charge. For Na⁺: 11 - (+1) = 10 electrons. For Cl⁻: 17 - (-1) = 18 electrons (subtracting negative adds!). For Mg²⁺: 12 - (+2) = 10 electrons. Quick check: cations should have fewer electrons than protons (positive charge makes sense), anions should have more electrons than protons (negative charge makes sense). If your ion doesn't match this, recheck your electron counting!

Question 6

Lithium (Li) is a group 1 element with atomic number 3. It commonly forms Li. Which option correctly explains what changes when Li becomes Li?

Li gains 1 electron to complete its first shell, forming Li with 4 electrons.
Li loses 1 valence electron, forming Li with 2 electrons and a stable configuration like helium. (correct answer)
Li loses 2 electrons to form Li with 1 electron, matching hydrogens configuration.
Li gains 7 electrons to complete an octet, forming Li with 10 electrons like neon.

Question 7

A sodium atom (Na, atomic number 11) has the electron configuration $1s^2\,2s^2\,2p^6\,3s^1$ . It commonly forms the ion Na. Which explanation best describes how the neutral atom becomes Na and why that charge forms?

Na gains 1 electron to fill its third shell, forming Na with 12 electrons and a +1 charge.
Na loses 1 valence electron (the $3s^1$ electron), forming Na with 10 electrons and a neon-like stable configuration. (correct answer)
Na loses 2 electrons to empty the third shell, forming Na with 9 electrons and a stable configuration like fluorine.
Na gains 7 electrons to complete an octet in the third shell, forming Na with 18 electrons like argon.

Question 8

Calcium (Ca) is in group 2 and has atomic number 20. It commonly forms Ca. Which explanation best connects calciums periodic table position to the ion charge?

Ca is in group 2, so it gains 2 electrons to form Ca and complete an octet.
Ca is in group 2, so it loses 2 valence electrons to form Ca, achieving an argon-like electron configuration. (correct answer)
Ca is in group 2, so it loses 1 electron to form Ca because it is closest to potassium.
Ca is in group 2, so it loses 20 electrons to form Ca and become stable.

Question 9

Aluminum (Al) is in Group 13 and has atomic number 13. It commonly forms Al³⁺. Which statement best explains the formation of Al³⁺ from a neutral Al atom?

Al gains 3 electrons to fill its valence shell and becomes Al³⁻ with a neon-like configuration.
Al loses 3 valence electrons to achieve a noble gas configuration like Ne, forming Al³⁺. (correct answer)
Al loses 1 electron because Group 13 elements always form +1 ions, forming Al⁺.
Al forms Al³⁺ by losing 3 neutrons to become more stable.

Explanation: This question tests your understanding of why and how atoms form ions by losing or gaining electrons to achieve stable electron configurations like those of noble gases. Atoms form ions to achieve stable electron configurations, typically matching the nearest noble gas (helium, neon, argon) which have full outer electron shells: metals (left side of periodic table, groups 1-3) form positive ions (cations) by LOSING their few valence electrons, leaving them with a full inner shell matching the previous noble gas. Nonmetals (right side, groups 15-17) form negative ions (anions) by GAINING electrons to complete their outer shells and match the next noble gas. For aluminum (Al, atomic number 13, electron configuration 1s² 2s² 2p⁶ 3s² 3p¹), it loses its 3 valence electrons (3s² 3p¹), resulting in Al³⁺ with 10 electrons and the configuration 1s² 2s² 2p⁶, matching neon's stable arrangement—fantastic job connecting this to group trends! Choice B correctly explains ion formation by identifying that aluminum loses 3 electrons to achieve the stable neon configuration, forming Al³⁺. Choice A fails because aluminum, as a metal, loses electrons rather than gaining them, and gaining would form a negative ion, not Al³⁺; choices C and D suggest losing only 1 or involving neutrons, which doesn't align with group 13's +3 charge or stability. The ion charge prediction recipe from periodic table: (1) Identify group number: Groups 1, 2, 13 are metals that LOSE electrons. Groups 15, 16, 17 are nonmetals that GAIN electrons. (2) Predict charge from group: Group 1 loses 1 → forms +1. Group 2 loses 2 → forms +2. Group 13 loses 3 → forms +3. Group 15 gains 3 → forms -3. Group 16 gains 2 → forms -2. Group 17 gains 1 → forms -1. The pattern: for metals, positive charge equals group number (mostly). For nonmetals, negative charge equals 8 minus group number (to reach 8 valence). (3) Verify with noble gas: Which noble gas is nearest? Metals lose to match previous noble gas (sodium matches neon by losing 1). Nonmetals gain to match next noble gas (chlorine matches argon by gaining 1). This method predicts common ions reliably! Electron bookkeeping for ions: if atom has 11 electrons and forms +1 ion, it LOST 1 electron, leaving 10. If atom has 17 electrons and forms -1 ion, it GAINED 1 electron, giving 18. The math: ion electrons = atomic number - charge. For Na⁺: 11 - (+1) = 10 electrons. For Cl⁻: 17 - (-1) = 18 electrons (subtracting negative adds!). For Mg²⁺: 12 - (+2) = 10 electrons. Quick check: cations should have fewer electrons than protons (positive charge makes sense), anions should have more electrons than protons (negative charge makes sense). If your ion doesn't match this, recheck your electron counting!

Question 10

Sodium (Na) is a Group 1 element with atomic number 11. A neutral sodium atom becomes a sodium ion, Na⁺. Which statement best explains why Na forms Na⁺?

Na gains 1 electron to fill its valence shell and becomes Na⁻ with a neon-like configuration.
Na loses 1 valence electron to achieve a stable noble gas configuration like Ne, forming Na⁺. (correct answer)
Na loses 2 electrons to reach a stable configuration like He, forming Na²⁺.
Na forms Na⁺ by losing 1 proton so the number of protons equals the number of electrons.

Explanation: This question tests your understanding of why and how atoms form ions by losing or gaining electrons to achieve stable electron configurations like those of noble gases. Atoms form ions to achieve stable electron configurations, typically matching the nearest noble gas (helium, neon, argon) which have full outer electron shells: metals (left side of periodic table, groups 1-3) form positive ions (cations) by LOSING their few valence electrons, leaving them with a full inner shell matching the previous noble gas. Nonmetals (right side, groups 15-17) form negative ions (anions) by GAINING electrons to complete their outer shells and match the next noble gas. For sodium (Na, atomic number 11, electron configuration 1s² 2s² 2p⁶ 3s¹), it loses its 1 valence electron from the 3s orbital, resulting in Na⁺ with 10 electrons and the configuration 1s² 2s² 2p⁶, matching neon's stable setup—great job recognizing how this stability drives ion formation! Choice B correctly explains ion formation by identifying that sodium loses 1 electron to achieve the stable neon configuration, forming Na⁺. Choice A fails because sodium, as a metal, loses electrons rather than gaining them, and gaining would form a negative ion, not the observed Na⁺; similarly, choices C and D incorrectly suggest losing 2 electrons or protons, which wouldn't match neon or involve electron changes properly. The ion charge prediction recipe from periodic table: (1) Identify group number: Groups 1, 2, 13 are metals that LOSE electrons. Groups 15, 16, 17 are nonmetals that GAIN electrons. (2) Predict charge from group: Group 1 loses 1 → forms +1. Group 2 loses 2 → forms +2. Group 13 loses 3 → forms +3. Group 15 gains 3 → forms -3. Group 16 gains 2 → forms -2. Group 17 gains 1 → forms -1. The pattern: for metals, positive charge equals group number (mostly). For nonmetals, negative charge equals 8 minus group number (to reach 8 valence). (3) Verify with noble gas: Which noble gas is nearest? Metals lose to match previous noble gas (sodium matches neon by losing 1). Nonmetals gain to match next noble gas (chlorine matches argon by gaining 1). This method predicts common ions reliably! Electron bookkeeping for ions: if atom has 11 electrons and forms +1 ion, it LOST 1 electron, leaving 10. If atom has 17 electrons and forms -1 ion, it GAINED 1 electron, giving 18. The math: ion electrons = atomic number - charge. For Na⁺: 11 - (+1) = 10 electrons. For Cl⁻: 17 - (-1) = 18 electrons (subtracting negative adds!). For Mg²⁺: 12 - (+2) = 10 electrons. Quick check: cations should have fewer electrons than protons (positive charge makes sense), anions should have more electrons than protons (negative charge makes sense). If your ion doesn't match this, recheck your electron counting!