Periodic Trends Flashcards: Atomic Radius, Ionization Energy & Electronegativity

Review 88 concise cards on atomic and ionic radius, shielding, effective nuclear charge, ionization energy, electron affinity, electronegativity, metallic character, exceptions, and comparisons.

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Periodic Trends Flashcards: Atomic Radius, Ionization Energy & Electronegativity

Study the core periodic trends with 88 independently written English flashcards for high-school and introductory-college chemistry. The deck separates broad patterns from the reasons behind them and uses generally where real configurations create exceptions.

What the cards practice

The sequence covers four useful recall paths: term to definition; table movement to a general property direction; cause to effect through shell number, shielding, distance, and effective nuclear charge; and a concrete pair or isoelectronic set to the expected comparison. Atomic and ionic radius, first and successive ionization energies, electron affinity, electronegativity, metallic character, and selected reactivity links are all included.

The course-level exceptions are deliberately small: Be versus B, Mg versus Al, N versus O, P versus S, and Cl versus F electron affinity. Electron-affinity wording distinguishes a favorable electron gain from the sign convention used by a source. Electronegativity stays tied to bonded atoms, and ionic-radius comparisons state when an isoelectronic rule applies.

Learning order

Definitions and table structure come first. General directions follow, then causal models, ion-size rules, successive-ionization reasoning, limited exceptions, and applied comparisons. Related prompts are spaced apart in a fixed order; the review scheduler handles longer-term interleaving after installation.

Scope

This deck teaches qualitative periodic-trend reasoning. It excludes exact numerical property tables, memorizing values for all 118 elements, advanced transition-metal irregularities, diagonal relationships, melting and boiling trends, broad group trivia, and copied examination or competitor material. It supports chemistry practice but does not replace calculation, laboratory, or full-course problem solving.

Sources and license

Core trends and explanations were checked against OpenStax Chemistry: Atoms First 2e, section 3.5 and its electronegativity discussion in section 4.2. Terminology was cross-checked against the IUPAC Gold Book entries for ionization energy, electron affinity, and electronegativity.

The prompts, answers, examples, organization, metadata, and generated cover were created independently from common chemistry knowledge and original work. No protected cards, textbook prose, source figures, exact property tables, logos, or third-party media were copied.

The Common knowledge · CC0 1.0 label applies only to the original prompts, answers, examples, organization, metadata, and cover, to the extent applicable rights exist. It does not claim ownership of scientific facts or third-party material.

Source review date: August 29, 2026.

Karty w tej talii

  1. Karta 1

    Pytanie

    What is a periodic trend?

    Odpowiedź

    A recurring pattern in element properties as atomic number increases across periods and down groups.

  2. Karta 2

    Pytanie

    What does covalent radius measure?

    Odpowiedź

    Half the distance between the nuclei of two identical atoms joined by a covalent bond.

  3. Karta 3

    Pytanie

    What is first ionization energy?

    Odpowiedź

    The minimum energy needed to remove the most loosely bound electron from an isolated gaseous atom in its ground state.

  4. Karta 4

    Pytanie

    What is electronegativity?

    Odpowiedź

    An atom's ability to attract shared electrons toward itself in a chemical bond.

  5. Karta 5

    Pytanie

    What is a period on the periodic table?

    Odpowiedź

    A horizontal row. For main-group elements, moving across a period fills orbitals in the same principal electron shell.

  6. Karta 6

    Pytanie

    What is ionic radius?

    Odpowiedź

    A measure of an ion's size, usually inferred from distances between ions in crystals.

  7. Karta 7

    Pytanie

    What does electron affinity describe?

    Odpowiedź

    The energy change when an electron is added to an isolated gaseous atom to form a gaseous anion.

  8. Karta 8

    Pytanie

    What does metallic character describe?

    Odpowiedź

    How readily an element shows metallic behavior, especially losing valence electrons and forming cations.

  9. Karta 9

    Pytanie

    What is a group on the periodic table?

    Odpowiedź

    A vertical column. Main-group elements in one group usually share a valence-electron pattern and similar chemistry.

  10. Karta 10

    Pytanie

    What is effective nuclear charge?

    Odpowiedź

    The net positive pull an electron feels from the nucleus after shielding and electron–electron repulsion are taken into account.

  11. Karta 11

    Pytanie

    What are successive ionization energies?

    Odpowiedź

    The energies needed to remove electrons one after another from the same atom, then from its increasingly positive ions.

  12. Karta 12

    Pytanie

    How does electronegativity difference relate to bond polarity?

    Odpowiedź

    A larger difference generally produces a more uneven electron distribution and a more polar bond.

  13. Karta 13

    Pytanie

    Why do main-group elements in one group often behave similarly?

    Odpowiedź

    They have the same general number and arrangement of valence electrons, which drive much of their bonding and reactivity.

  14. Karta 14

    Pytanie

    What is electron shielding?

    Odpowiedź

    The reduction in nuclear attraction felt by an electron because other electrons lie between it and the nucleus and repel it.

  15. Karta 15

    Pytanie

    Why does the definition of ionization energy specify a gaseous atom?

    Odpowiedź

    It isolates the atom from bonding and intermolecular effects, so the energy reflects electron removal from that species itself.

  16. Karta 16

    Pytanie

    Where are metals and nonmetals generally found on the periodic table?

    Odpowiedź

    Metals occupy the left and center; nonmetals cluster toward the upper right, with metalloids near the boundary.

  17. Karta 17

    Pytanie

    What changes in the electron arrangement across a main-group period?

    Odpowiedź

    Electrons are added to the same principal shell while the nucleus gains one proton from one element to the next.

  18. Karta 18

    Pytanie

    How does atomic radius generally change from left to right across a period?

    Odpowiedź

    It decreases.

  19. Karta 19

    Pytanie

    How does first ionization energy generally change from left to right across a period?

    Odpowiedź

    It increases, although a few recurring subshell and electron-pairing exceptions interrupt the rise.

  20. Karta 20

    Pytanie

    How does electronegativity generally change from left to right across a period?

    Odpowiedź

    It increases for the elements normally assigned electronegativity values.

  21. Karta 21

    Pytanie

    What changes in the electron arrangement down a main-group group?

    Odpowiedź

    Each step adds a higher principal electron shell while preserving a similar valence-electron pattern.

  22. Karta 22

    Pytanie

    How does atomic radius generally change down a group?

    Odpowiedź

    It increases.

  23. Karta 23

    Pytanie

    How does first ionization energy generally change down a group?

    Odpowiedź

    It decreases.

  24. Karta 24

    Pytanie

    How does electronegativity generally change down a group?

    Odpowiedź

    It decreases.

  25. Karta 25

    Pytanie

    How does effective nuclear charge generally change across a main-group period?

    Odpowiedź

    It increases because nuclear charge rises while added electrons enter the same principal shell and do not fully shield one another.

  26. Karta 26

    Pytanie

    How does a cation's radius compare with its neutral parent atom?

    Odpowiedź

    The cation is smaller.

  27. Karta 27

    Pytanie

    How does electron addition generally change across a period?

    Odpowiedź

    It generally becomes more energetically favorable toward the right, but electron affinity has substantial exceptions and depends on the sign convention used.

  28. Karta 28

    Pytanie

    How does metallic character generally change from left to right across a period?

    Odpowiedź

    It decreases.

  29. Karta 29

    Pytanie

    Why are valence electrons generally farther from the nucleus down a group?

    Odpowiedź

    They occupy shells with higher principal quantum numbers, so the electron cloud extends farther outward.

  30. Karta 30

    Pytanie

    How does an anion's radius compare with its neutral parent atom?

    Odpowiedź

    The anion is larger.

  31. Karta 31

    Pytanie

    How does favorable electron addition generally change down a group?

    Odpowiedź

    It generally becomes less favorable as the added electron enters a larger, more shielded shell, though electron-affinity irregularities are common.

  32. Karta 32

    Pytanie

    How does metallic character generally change down a group?

    Odpowiedź

    It increases.

  33. Karta 33

    Pytanie

    Why does shielding change less than nuclear charge across a main-group period?

    Odpowiedź

    The added electrons enter the same principal shell, so they do not shield one another as effectively as inner-shell electrons do.

  34. Karta 34

    Pytanie

    Which has the larger atomic radius, Li or Na?

    Odpowiedź

    Na. It lies below Li and has an additional occupied electron shell.

  35. Karta 35

    Pytanie

    Which has the larger atomic radius, Na or Mg?

    Odpowiedź

    Na. Atomic radius generally decreases from left to right across Period 3.

  36. Karta 36

    Pytanie

    How does greater electron–nucleus distance affect electrostatic attraction?

    Odpowiedź

    It weakens the attraction, all else being equal.

  37. Karta 37

    Pytanie

    How do successive ionization energies for one element compare?

    Odpowiedź

    Each successive ionization energy is higher than the one before it because an electron is removed from an increasingly positive species.

  38. Karta 38

    Pytanie

    Which has the higher first ionization energy, Li or Na?

    Odpowiedź

    Li. Its valence electron is closer to the nucleus and less shielded.

  39. Karta 39

    Pytanie

    Which has the higher first ionization energy, Na or Mg?

    Odpowiedź

    Mg. Its greater effective nuclear charge holds the valence electrons more tightly.

  40. Karta 40

    Pytanie

    Why does forming a cation usually shrink an atom?

    Odpowiedź

    Electron loss reduces electron–electron repulsion and increases the nuclear pull per remaining electron; losing the outer shell can shrink it sharply.

  41. Karta 41

    Pytanie

    Which element is most electronegative on the Pauling scale?

    Odpowiedź

    Fluorine.

  42. Karta 42

    Pytanie

    Which is more electronegative, Li or Na?

    Odpowiedź

    Li. Electronegativity generally decreases down Group 1.

  43. Karta 43

    Pytanie

    Which is more electronegative, Na or Mg?

    Odpowiedź

    Mg. Electronegativity generally increases across Period 3.

  44. Karta 44

    Pytanie

    What does a large jump between successive ionization energies reveal?

    Odpowiedź

    The next electron would come from a lower, core shell; the number removed before the jump indicates the valence-electron count for a main-group atom.

  45. Karta 45

    Pytanie

    Why is Cl⁻ larger than neutral Cl?

    Odpowiedź

    The added electron increases repulsion within the valence shell while the nuclear charge stays the same.

  46. Karta 46

    Pytanie

    How do you compare the radii of isoelectronic species?

    Odpowiedź

    The species with more protons is smaller because the same number of electrons feels a stronger nuclear attraction.

  47. Karta 47

    Pytanie

    Why does an atom have no single sharp physical radius?

    Odpowiedź

    Its electron cloud has no hard edge, so atomic size depends on a defined measurement such as covalent, metallic, or van der Waals radius.

  48. Karta 48

    Pytanie

    Why are noble-gas electronegativities often omitted in introductory tables?

    Odpowiedź

    Electronegativity describes attraction in a bond, and many noble gases form too few ordinary bonds for a standard value to be useful on common scales.

  49. Karta 49

    Pytanie

    Why does forming an anion usually expand an atom?

    Odpowiedź

    The extra electron increases electron–electron repulsion and lowers the nuclear pull available per electron.

  50. Karta 50

    Pytanie

    Order O²⁻, F⁻, and Ne from largest to smallest radius.

    Odpowiedź

    O²⁻ > F⁻ > Ne. All have 10 electrons, and increasing proton count pulls that electron cloud inward.

  51. Karta 51

    Pytanie

    After which removal does Na show its first large ionization-energy jump?

    Odpowiedź

    After the first electron. Removing one valence electron leaves a stable core, so the second removal reaches that core.

  52. Karta 52

    Pytanie

    Does electronegativity difference create a universal ionic-versus-covalent cutoff?

    Odpowiedź

    No. A larger difference usually means more bond polarity, but bonding lies on a continuum and context matters.

  53. Karta 53

    Pytanie

    How do noble gases generally differ from halogens in electron affinity?

    Odpowiedź

    Adding an electron to a noble gas is generally unfavorable because it must begin a higher-energy shell; halogens usually gain one much more favorably.

  54. Karta 54

    Pytanie

    Which is smaller, Na⁺ or Mg²⁺?

    Odpowiedź

    Mg²⁺. Both have 10 electrons, but Mg²⁺ has one more proton.

  55. Karta 55

    Pytanie

    After which removal does Mg show its first large ionization-energy jump?

    Odpowiedź

    After the second electron. Mg has two valence electrons, so the third removal reaches a core shell.

  56. Karta 56

    Pytanie

    How does electronegativity differ from electron affinity?

    Odpowiedź

    Electronegativity is a relative measure of attraction for shared electrons in a bond; electron affinity is an energy change for adding an electron to an isolated gaseous species.

  57. Karta 57

    Pytanie

    How are atomic radius and first ionization energy generally related?

    Odpowiedź

    A larger radius usually means a lower first ionization energy because the valence electron is farther from the nucleus and easier to remove.

  58. Karta 58

    Pytanie

    Which has the more exothermic first electron affinity, F or Cl?

    Odpowiedź

    Cl. Fluorine's very compact 2p shell creates stronger electron–electron repulsion for the incoming electron, so this pair breaks the simple down-group expectation.

  59. Karta 59

    Pytanie

    Which has the higher first ionization energy, Be or B?

    Odpowiedź

    Be. B loses a higher-energy 2p electron, while Be loses a more penetrating 2s electron from a filled 2s subshell.

  60. Karta 60

    Pytanie

    Why does Group 1 metal reactivity generally increase down the group?

    Odpowiedź

    The valence electron is farther out and more shielded, so its first ionization energy falls and electron loss becomes easier.

  61. Karta 61

    Pytanie

    How are atomic radius and electronegativity generally related?

    Odpowiedź

    Smaller atoms usually attract bonding electrons more strongly, so electronegativity tends to rise as radius falls.

  62. Karta 62

    Pytanie

    Why is Na⁺ much smaller than neutral Na?

    Odpowiedź

    Na loses its entire third-shell valence level, leaving the smaller neon-like electron configuration.

  63. Karta 63

    Pytanie

    Which has the higher first ionization energy, Mg or Al?

    Odpowiedź

    Mg. Al's removed electron is a higher-energy 3p electron, while Mg loses a more penetrating 3s electron from a filled 3s subshell.

  64. Karta 64

    Pytanie

    Why does halogen reactivity generally decrease down Group 17?

    Odpowiedź

    Larger radius and greater shielding weaken attraction for an incoming electron, so oxidizing ability generally falls. Particular reactions still depend on bond energies and conditions.

  65. Karta 65

    Pytanie

    Why do Groups 2 and 15 often interrupt the simple electron-affinity trend?

    Odpowiedź

    Group 2 has a filled s subshell and Group 15 has a half-filled p subshell, so an added electron enters a less favorable arrangement.

  66. Karta 66

    Pytanie

    Can ion charge alone rank two unrelated ionic radii?

    Odpowiedź

    No. Shell number, electron count, proton count, oxidation state, and crystal environment can all matter; the isoelectronic rule needs the same electron count.

  67. Karta 67

    Pytanie

    Which has the higher first ionization energy, N or O?

    Odpowiedź

    N. Its half-filled 2p subshell is relatively stable; O has one paired 2p orbital, and repulsion makes one electron easier to remove.

  68. Karta 68

    Pytanie

    In which direction does nonmetallic character generally increase?

    Odpowiedź

    Up and to the right, opposite the general trend in metallic character.

  69. Karta 69

    Pytanie

    Within the same principal shell, which penetrates closer to the nucleus: an s or p orbital?

    Odpowiedź

    An s orbital. Greater penetration means its electrons are less shielded and usually lower in energy than p electrons in the same shell.

  70. Karta 70

    Pytanie

    How do same-charge ion radii generally change down a group?

    Odpowiedź

    They increase as occupied electron shells are added.

  71. Karta 71

    Pytanie

    Which has the higher first ionization energy, P or S?

    Odpowiedź

    P. Its half-filled 3p subshell is relatively stable; S contains a paired 3p orbital that increases repulsion and eases removal.

  72. Karta 72

    Pytanie

    Why should simple periodic-direction rules be used cautiously for transition metals?

    Odpowiedź

    d-electron filling, shielding, oxidation state, and contraction effects make their property changes less regular than main-group trends.

  73. Karta 73

    Pytanie

    Why do periodic-trend statements usually say “generally”?

    Odpowiedź

    Subshell energies, electron pairing, radius definitions, and element-specific configurations create real exceptions to the broad patterns.

  74. Karta 74

    Pytanie

    Which has the larger atomic radius, K or Br?

    Odpowiedź

    K. Both are in Period 4, and atomic radius generally decreases from left to right.

  75. Karta 75

    Pytanie

    Which has the higher first ionization energy, Mg or Cl?

    Odpowiedź

    Cl. Its valence electrons experience greater effective nuclear charge and are held more tightly.

  76. Karta 76

    Pytanie

    Which is more electronegative, Al or Si?

    Odpowiedź

    Si. Electronegativity generally increases across Period 3.

  77. Karta 77

    Pytanie

    Which has the larger atomic radius, O or F?

    Odpowiedź

    O. Atomic radius generally decreases across Period 2.

  78. Karta 78

    Pytanie

    Which has the higher first ionization energy, K or Br?

    Odpowiedź

    Br. First ionization energy generally increases across Period 4.

  79. Karta 79

    Pytanie

    Which is more electronegative, Mg or Cl?

    Odpowiedź

    Cl. It lies farther right in Period 3.

  80. Karta 80

    Pytanie

    Which has the larger atomic radius, Al or Si?

    Odpowiedź

    Al. Atomic radius generally decreases across Period 3 as effective nuclear charge rises.

  81. Karta 81

    Pytanie

    Which has the higher first ionization energy, O or F?

    Odpowiedź

    F. This pair follows the general increase across Period 2.

  82. Karta 82

    Pytanie

    Which is more electronegative, K or Br?

    Odpowiedź

    Br. Electronegativity generally increases across Period 4.

  83. Karta 83

    Pytanie

    Which has the larger atomic radius, Mg or Cl?

    Odpowiedź

    Mg. Both are in Period 3, and Mg lies farther left.

  84. Karta 84

    Pytanie

    Which has the higher first ionization energy, Al or Si?

    Odpowiedź

    Si. This pair follows the general increase across Period 3.

  85. Karta 85

    Pytanie

    Which is more electronegative, O or F?

    Odpowiedź

    F, the most electronegative element on the Pauling scale.

  86. Karta 86

    Pytanie

    Order Al³⁺, Mg²⁺, Na⁺, Ne, F⁻, and O²⁻ from smallest to largest radius.

    Odpowiedź

    Al³⁺ < Mg²⁺ < Na⁺ < Ne < F⁻ < O²⁻. All have 10 electrons, so radius grows as proton count falls.

  87. Karta 87

    Pytanie

    Why do upper-right nonmetals usually hold valence electrons tightly?

    Odpowiedź

    Their relatively small radii and high effective nuclear charges create strong attraction between the nucleus and valence electrons.

  88. Karta 88

    Pytanie

    Across a main-group period, what shared cause links smaller radius, higher ionization energy, and higher electronegativity?

    Odpowiedź

    Increasing effective nuclear charge pulls the same-shell valence electrons inward and holds them more strongly.

A glowing field of blank periodic-table tiles surrounded by blue and amber abstract atomic forms.

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Periodic Trends Flashcards: Atomic Radius, Ionization Energy & Electronegativity

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