Isoelectronic Ion Flashcards: Electron Counts & Radius Ranking
Count electrons, find matching ion configurations, rank ionic radii, and repair common charge and ordering errors with 42 short chemistry flashcards.
ఈ డెక్ గురించి
Practice isoelectronic ions with 42 short English flashcards. Work with familiar monatomic ground-state ions in the 10-electron [Ne] and 18-electron [Ar] groups: N³⁻, O²⁻, F⁻, Na⁺, Mg²⁺, Al³⁺, P³⁻, S²⁻, Cl⁻, K⁺, and Ca²⁺. Atomic number Z is supplied whenever counting is the task.
The cards practice ion and Z → electron count, small list → matching-configuration group or outlier, confirmed isoelectronic pair or set → qualitative radius comparison, and constrained proton/electron counts → charge or ion symbol. Short error-repair cards address sign mistakes, equal-count/equal-size confusion, incorrect groupings, reversed orders, and skipped configuration checks. A few evidence-limit questions test what this rule can establish. Answers start with the result and give a brief explanation.
The sequence starts with charge bookkeeping and unchanged nuclei, introduces the 10-electron group, then brings in the 18-electron group before interleaving comparisons, constrained inverses, and repairs. Closely related variants are separated. Numerical radii, neutral noble-gas radius comparisons, full electron-configuration derivation, transition-metal and coordination cases, molecular species, broad periodic trends, isotope drills, and full-course or exam coverage are excluded to keep each decision short and well defined. Unconstrained radius → ion identification and exhaustive reverse/permutation cards are excluded because they do not provide one clear answer.
Original questions, explanations, organization, and metadata were written with AI assistance from common scientific facts, with factual checks against Purdue’s isoelectronic glossary, Purdue’s ionic-size lesson, and NIST’s atomic-number table. The cover is an original AI-generated conceptual illustration, not a particle-count or radius-scale diagram. CC0 1.0 applies to the original deck text, organization, metadata, and cover to the extent applicable rights exist. Scientific facts are not owned; referenced works retain their own rights. No source or competitor prose, exercises, tables, or diagrams are reproduced.
An independent learning resource with no claimed curriculum or exam alignment, affiliation, or endorsement.
ఈ డెక్‌లోని కార్డులు
కార్డు 1
ప్రశ్న
For a monatomic ion, how do atomic number Z and signed charge q give its electron count?
సమాధానం
Electron count = Z − q. Use q = +2 for a 2+ ion and q = −2 for a 2− ion.
కార్డు 2
ప్రశ్న
When an atom forms a monatomic ion by gaining or losing electrons, what happens to its proton count?
సమాధానం
It stays the same. Ion formation changes the electron count, not the element’s atomic number.
కార్డు 3
ప్రశ్న
Na⁺, Z = 11: electron count?
సమాధానం
10 electrons. The 1+ charge means one fewer electron than the 11 protons.
కార్డు 4
ప్రశ్న
What does isoelectronic mean for the closed-shell monatomic ions compared here?
సమాధానం
They have the same electron configuration. For these ground-state 10- or 18-electron ions, matching electron totals gives the matching configuration.
కార్డు 5
ప్రశ్న
O²⁻, Z = 8: electron count?
సమాధానం
10 electrons. The 2− charge means two more electrons than the eight protons.
కార్డు 6
ప్రశ్న
A magnesium ion has 12 protons and 10 electrons. What is its signed charge?
సమాధానం
2+. There are two more protons than electrons: 12 − 10 = +2.
కార్డు 7
ప్రశ్న
Cl⁻, Z = 17: electron count?
సమాధానం
18 electrons. A 1− ion has one more electron than its proton count.
కార్డు 8
ప్రశ్న
O²⁻ (Z = 8) and Mg²⁺ (Z = 12) both have 10 electrons. Which has the smaller ionic radius?
సమాధానం
Mg²⁺. With the same electron configuration, its greater proton count pulls the electron cloud closer.
కార్డు 9
ప్రశ్న
Al³⁺, Z = 13: electron count?
సమాధానం
10 electrons. Subtract the positive charge: 13 − 3 = 10.
కార్డు 10
ప్రశ్న
Which ion has the same electron configuration as Na⁺ (Z = 11): F⁻ (Z = 9), K⁺ (Z = 19), or Ca²⁺ (Z = 20)?
సమాధానం
F⁻. Both F⁻ and Na⁺ have 10 electrons; K⁺ and Ca²⁺ each have 18.
కార్డు 11
ప్రశ్న
A learner writes: “P³⁻ has 15 − 3 = 12 electrons.” With Z = 15, repair the calculation.
సమాధానం
15 + 3 = 18 electrons. A negative charge adds electrons to the neutral count.
కార్డు 12
ప్రశ్న
A monatomic ion has more electrons than protons. What sign must its charge have?
సమాధానం
Negative. The excess electrons give a net negative charge.
కార్డు 13
ప్రశ్న
N³⁻ (Z = 7) and Na⁺ (Z = 11) both have 10 electrons. Which has the larger ionic radius?
సమాధానం
N³⁻. Its smaller proton count holds the same electron configuration less tightly.
కార్డు 14
ప్రశ్న
N³⁻, Z = 7: electron count?
సమాధానం
10 electrons. Add three for the 3− charge: 7 + 3 = 10.
కార్డు 15
ప్రశ్న
Does the isoelectronic radius rule justify ranking F⁻ (Z = 9) and Cl⁻ (Z = 17) by proton count alone?
సమాధానం
No. F⁻ has 10 electrons and Cl⁻ has 18, so their configurations differ. This rule alone does not establish their order.
కార్డు 16
ప్రశ్న
Which aluminium ion has 13 protons and 10 electrons? Give its symbol and charge.
సమాధానం
Al³⁺. The three-electron deficit gives a 3+ charge.
కార్డు 17
ప్రశ్న
All three ions have 10 electrons. Rank O²⁻ (Z = 8), Mg²⁺ (Z = 12), and F⁻ (Z = 9) by increasing ionic radius.
సమాధానం
Mg²⁺ < F⁻ < O²⁻. Increasing radius follows decreasing proton count within this series.
కార్డు 18
ప్రశ్న
S²⁻, Z = 16: electron count?
సమాధానం
18 electrons. Add two for the 2− charge: 16 + 2 = 18.
కార్డు 19
ప్రశ్న
A learner says Na⁺ (Z = 11) and Al³⁺ (Z = 13) have equal radii because both have 10 electrons. Repair the conclusion.
సమాధానం
Al³⁺ has the smaller radius. Equal electron configurations do not mean equal sizes; Al³⁺ has the greater nuclear charge.
కార్డు 20
ప్రశ్న
Which ions form the 18-electron group: P³⁻ (Z = 15), Mg²⁺ (Z = 12), Cl⁻ (Z = 17), and S²⁻ (Z = 16)?
సమాధానం
P³⁻, Cl⁻, and S²⁻. Each has 18 electrons; Mg²⁺ has 10.
కార్డు 21
ప్రశ్న
O²⁻ (Z = 8) and F⁻ (Z = 9) both have 10 electrons. Which has the larger ionic radius?
సమాధానం
O²⁻. Its eight protons attract the same electron configuration less strongly than the nine protons in F⁻.
కార్డు 22
ప్రశ్న
A phosphorus ion has 15 protons and 18 electrons. What is its signed charge?
సమాధానం
3−. Three excess electrons give a charge of −3.
కార్డు 23
ప్రశ్న
For 10-electron ions, a learner gives this increasing-radius order: N³⁻ < Na⁺ < Al³⁺. Z values are 7, 11, and 13. Repair the order.
సమాధానం
Al³⁺ < Na⁺ < N³⁻. The greatest proton count gives the smallest radius in this series.
కార్డు 24
ప్రశ్న
Ca²⁺, Z = 20: electron count?
సమాధానం
18 electrons. Subtract two for the 2+ charge: 20 − 2 = 18.
కార్డు 25
ప్రశ్న
Do an ion’s proton and electron counts give its exact ionic radius in picometres?
సమాధానం
No. They support a qualitative comparison within a matching-configuration series, not an exact radius value.
కార్డు 26
ప్రశ్న
K⁺ (Z = 19) and Ca²⁺ (Z = 20) both have 18 electrons. Which has the smaller ionic radius?
సమాధానం
Ca²⁺. Its extra proton attracts the same electron configuration more strongly.
కార్డు 27
ప్రశ్న
A learner groups F⁻ (Z = 9) with Cl⁻ (Z = 17) as isoelectronic because both are 1−. Repair the grouping claim.
సమాధానం
They are not isoelectronic. F⁻ has 10 electrons and Cl⁻ has 18; the same ionic charge does not guarantee the same configuration.
కార్డు 28
ప్రశ్న
A sulfur ion has 16 protons and 18 electrons. What is its signed charge?
సమాధానం
2−. It has two more electrons than protons.
కార్డు 29
ప్రశ్న
All three ions have 18 electrons. Rank Cl⁻ (Z = 17), S²⁻ (Z = 16), and Ca²⁺ (Z = 20) by increasing ionic radius.
సమాధానం
Ca²⁺ < Cl⁻ < S²⁻. Within the shared configuration, radius increases as proton count decreases.
కార్డు 30
ప్రశ్న
K⁺, Z = 19: electron count?
సమాధానం
18 electrons. A 1+ charge removes one electron from the neutral count.
కార్డు 31
ప్రశ్న
A learner says Mg²⁺ has 12 electrons because magnesium keeps its 12 protons when it ionizes. Repair the electron count.
సమాధానం
10 electrons. The 12 protons stay, while a 2+ charge means two fewer electrons.
కార్డు 32
ప్రశ్న
Which nitrogen ion has 7 protons and 10 electrons? Give its symbol and charge.
సమాధానం
N³⁻. Three excess electrons give a 3− charge.
కార్డు 33
ప్రశ్న
Are N³⁻ (Z = 7) and F⁻ (Z = 9) isoelectronic in their ground states?
సమాధానం
Yes. Each has 10 electrons and the same closed-shell configuration.
కార్డు 34
ప్రశ్న
All three ions have 18 electrons. Rank S²⁻ (Z = 16), K⁺ (Z = 19), and P³⁻ (Z = 15) by decreasing ionic radius.
సమాధానం
P³⁻ > S²⁻ > K⁺. Within this series, the ion with the fewest protons has the largest radius.
కార్డు 35
ప్రశ్న
A calcium ion has 20 protons and 18 electrons. A learner labels it Ca²⁻. Repair the charge sign.
సమాధానం
Ca²⁺. The ion has two more protons than electrons, so the charge is positive.
కార్డు 36
ప్రశ్న
Can you apply the isoelectronic radius rule to Mg²⁺ (Z = 12) and Ca²⁺ (Z = 20) just because both have charge 2+?
సమాధానం
No. Mg²⁺ has 10 electrons and Ca²⁺ has 18. A different comparison is needed; sharing a charge does not make this rule applicable.
కార్డు 37
ప్రశ్న
Which ion breaks the 10-electron group: O²⁻ (Z = 8), Ca²⁺ (Z = 20), F⁻ (Z = 9), or Mg²⁺ (Z = 12)?
సమాధానం
Ca²⁺. It has 18 electrons; the other three each have 10.
కార్డు 38
ప్రశ్న
A chlorine ion has 17 protons and 18 electrons. What is its signed charge?
సమాధానం
1−. One excess electron gives a charge of −1.
కార్డు 39
ప్రశ్న
A learner says O²⁻ is smaller than F⁻ because it is more negative. Both have 10 electrons; Z is 8 for O and 9 for F. Repair the comparison.
సమాధానం
O²⁻ is larger. Within the same configuration, its smaller proton count gives a weaker nuclear pull and a larger electron cloud.
కార్డు 40
ప్రశ్న
Al³⁺ (Z = 13) and Mg²⁺ (Z = 12) both have 10 electrons. Which has the smaller ionic radius?
సమాధానం
Al³⁺. It has more protons pulling on the same electron configuration.
కార్డు 41
ప్రశ్న
A solution ranks S²⁻ (Z = 16) and Na⁺ (Z = 11) by proton count alone. Which required check was skipped?
సమాధానం
Whether the electron configurations match. S²⁻ has 18 electrons and Na⁺ has 10, so the isoelectronic radius rule cannot justify that ranking.
కార్డు 42
ప్రశ్న
Can a qualitative ionic-radius rank, with no element, charge, or candidate list, uniquely identify an ion?
సమాధానం
No. A size rank alone does not fix an element or charge. Identification needs further constraints, such as proton and electron counts.
42 కార్డులు
Isoelectronic Ion Flashcards: Electron Counts & Radius Ranking
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