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.
Um þennan stokk
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.
Spjöld í þessum stokki
Spjald 1
Spurning
What is a periodic trend?
Svar
A recurring pattern in element properties as atomic number increases across periods and down groups.
Spjald 2
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What does covalent radius measure?
Svar
Half the distance between the nuclei of two identical atoms joined by a covalent bond.
Spjald 3
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What is first ionization energy?
Svar
The minimum energy needed to remove the most loosely bound electron from an isolated gaseous atom in its ground state.
Spjald 4
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What is electronegativity?
Svar
An atom's ability to attract shared electrons toward itself in a chemical bond.
Spjald 5
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What is a period on the periodic table?
Svar
A horizontal row. For main-group elements, moving across a period fills orbitals in the same principal electron shell.
Spjald 6
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What is ionic radius?
Svar
A measure of an ion's size, usually inferred from distances between ions in crystals.
Spjald 7
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What does electron affinity describe?
Svar
The energy change when an electron is added to an isolated gaseous atom to form a gaseous anion.
Spjald 8
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What does metallic character describe?
Svar
How readily an element shows metallic behavior, especially losing valence electrons and forming cations.
Spjald 9
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What is a group on the periodic table?
Svar
A vertical column. Main-group elements in one group usually share a valence-electron pattern and similar chemistry.
Spjald 10
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What is effective nuclear charge?
Svar
The net positive pull an electron feels from the nucleus after shielding and electron–electron repulsion are taken into account.
Spjald 11
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What are successive ionization energies?
Svar
The energies needed to remove electrons one after another from the same atom, then from its increasingly positive ions.
Spjald 12
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How does electronegativity difference relate to bond polarity?
Svar
A larger difference generally produces a more uneven electron distribution and a more polar bond.
Spjald 13
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Why do main-group elements in one group often behave similarly?
Svar
They have the same general number and arrangement of valence electrons, which drive much of their bonding and reactivity.
Spjald 14
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What is electron shielding?
Svar
The reduction in nuclear attraction felt by an electron because other electrons lie between it and the nucleus and repel it.
Spjald 15
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Why does the definition of ionization energy specify a gaseous atom?
Svar
It isolates the atom from bonding and intermolecular effects, so the energy reflects electron removal from that species itself.
Spjald 16
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Where are metals and nonmetals generally found on the periodic table?
Svar
Metals occupy the left and center; nonmetals cluster toward the upper right, with metalloids near the boundary.
Spjald 17
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What changes in the electron arrangement across a main-group period?
Svar
Electrons are added to the same principal shell while the nucleus gains one proton from one element to the next.
Spjald 18
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How does atomic radius generally change from left to right across a period?
Svar
It decreases.
Spjald 19
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How does first ionization energy generally change from left to right across a period?
Svar
It increases, although a few recurring subshell and electron-pairing exceptions interrupt the rise.
Spjald 20
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How does electronegativity generally change from left to right across a period?
Svar
It increases for the elements normally assigned electronegativity values.
Spjald 21
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What changes in the electron arrangement down a main-group group?
Svar
Each step adds a higher principal electron shell while preserving a similar valence-electron pattern.
Spjald 22
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How does atomic radius generally change down a group?
Svar
It increases.
Spjald 23
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How does first ionization energy generally change down a group?
Svar
It decreases.
Spjald 24
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How does electronegativity generally change down a group?
Svar
It decreases.
Spjald 25
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How does effective nuclear charge generally change across a main-group period?
Svar
It increases because nuclear charge rises while added electrons enter the same principal shell and do not fully shield one another.
Spjald 26
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How does a cation's radius compare with its neutral parent atom?
Svar
The cation is smaller.
Spjald 27
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How does electron addition generally change across a period?
Svar
It generally becomes more energetically favorable toward the right, but electron affinity has substantial exceptions and depends on the sign convention used.
Spjald 28
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How does metallic character generally change from left to right across a period?
Svar
It decreases.
Spjald 29
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Why are valence electrons generally farther from the nucleus down a group?
Svar
They occupy shells with higher principal quantum numbers, so the electron cloud extends farther outward.
Spjald 30
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How does an anion's radius compare with its neutral parent atom?
Svar
The anion is larger.
Spjald 31
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How does favorable electron addition generally change down a group?
Svar
It generally becomes less favorable as the added electron enters a larger, more shielded shell, though electron-affinity irregularities are common.
Spjald 32
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How does metallic character generally change down a group?
Svar
It increases.
Spjald 33
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Why does shielding change less than nuclear charge across a main-group period?
Svar
The added electrons enter the same principal shell, so they do not shield one another as effectively as inner-shell electrons do.
Spjald 34
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Which has the larger atomic radius, Li or Na?
Svar
Na. It lies below Li and has an additional occupied electron shell.
Spjald 35
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Which has the larger atomic radius, Na or Mg?
Svar
Na. Atomic radius generally decreases from left to right across Period 3.
Spjald 36
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How does greater electron–nucleus distance affect electrostatic attraction?
Svar
It weakens the attraction, all else being equal.
Spjald 37
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How do successive ionization energies for one element compare?
Svar
Each successive ionization energy is higher than the one before it because an electron is removed from an increasingly positive species.
Spjald 38
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Which has the higher first ionization energy, Li or Na?
Svar
Li. Its valence electron is closer to the nucleus and less shielded.
Spjald 39
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Which has the higher first ionization energy, Na or Mg?
Svar
Mg. Its greater effective nuclear charge holds the valence electrons more tightly.
Spjald 40
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Why does forming a cation usually shrink an atom?
Svar
Electron loss reduces electron–electron repulsion and increases the nuclear pull per remaining electron; losing the outer shell can shrink it sharply.
Spjald 41
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Which element is most electronegative on the Pauling scale?
Svar
Fluorine.
Spjald 42
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Which is more electronegative, Li or Na?
Svar
Li. Electronegativity generally decreases down Group 1.
Spjald 43
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Which is more electronegative, Na or Mg?
Svar
Mg. Electronegativity generally increases across Period 3.
Spjald 44
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What does a large jump between successive ionization energies reveal?
Svar
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.
Spjald 45
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Why is Cl⁻ larger than neutral Cl?
Svar
The added electron increases repulsion within the valence shell while the nuclear charge stays the same.
Spjald 46
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How do you compare the radii of isoelectronic species?
Svar
The species with more protons is smaller because the same number of electrons feels a stronger nuclear attraction.
Spjald 47
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Why does an atom have no single sharp physical radius?
Svar
Its electron cloud has no hard edge, so atomic size depends on a defined measurement such as covalent, metallic, or van der Waals radius.
Spjald 48
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Why are noble-gas electronegativities often omitted in introductory tables?
Svar
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.
Spjald 49
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Why does forming an anion usually expand an atom?
Svar
The extra electron increases electron–electron repulsion and lowers the nuclear pull available per electron.
Spjald 50
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Order O²⁻, F⁻, and Ne from largest to smallest radius.
Svar
O²⁻ > F⁻ > Ne. All have 10 electrons, and increasing proton count pulls that electron cloud inward.
Spjald 51
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After which removal does Na show its first large ionization-energy jump?
Svar
After the first electron. Removing one valence electron leaves a stable core, so the second removal reaches that core.
Spjald 52
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Does electronegativity difference create a universal ionic-versus-covalent cutoff?
Svar
No. A larger difference usually means more bond polarity, but bonding lies on a continuum and context matters.
Spjald 53
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How do noble gases generally differ from halogens in electron affinity?
Svar
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.
Spjald 54
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Which is smaller, Na⁺ or Mg²⁺?
Svar
Mg²⁺. Both have 10 electrons, but Mg²⁺ has one more proton.
Spjald 55
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After which removal does Mg show its first large ionization-energy jump?
Svar
After the second electron. Mg has two valence electrons, so the third removal reaches a core shell.
Spjald 56
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How does electronegativity differ from electron affinity?
Svar
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.
Spjald 57
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How are atomic radius and first ionization energy generally related?
Svar
A larger radius usually means a lower first ionization energy because the valence electron is farther from the nucleus and easier to remove.
Spjald 58
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Which has the more exothermic first electron affinity, F or Cl?
Svar
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.
Spjald 59
Spurning
Which has the higher first ionization energy, Be or B?
Svar
Be. B loses a higher-energy 2p electron, while Be loses a more penetrating 2s electron from a filled 2s subshell.
Spjald 60
Spurning
Why does Group 1 metal reactivity generally increase down the group?
Svar
The valence electron is farther out and more shielded, so its first ionization energy falls and electron loss becomes easier.
Spjald 61
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How are atomic radius and electronegativity generally related?
Svar
Smaller atoms usually attract bonding electrons more strongly, so electronegativity tends to rise as radius falls.
Spjald 62
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Why is Na⁺ much smaller than neutral Na?
Svar
Na loses its entire third-shell valence level, leaving the smaller neon-like electron configuration.
Spjald 63
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Which has the higher first ionization energy, Mg or Al?
Svar
Mg. Al's removed electron is a higher-energy 3p electron, while Mg loses a more penetrating 3s electron from a filled 3s subshell.
Spjald 64
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Why does halogen reactivity generally decrease down Group 17?
Svar
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.
Spjald 65
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Why do Groups 2 and 15 often interrupt the simple electron-affinity trend?
Svar
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.
Spjald 66
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Can ion charge alone rank two unrelated ionic radii?
Svar
No. Shell number, electron count, proton count, oxidation state, and crystal environment can all matter; the isoelectronic rule needs the same electron count.
Spjald 67
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Which has the higher first ionization energy, N or O?
Svar
N. Its half-filled 2p subshell is relatively stable; O has one paired 2p orbital, and repulsion makes one electron easier to remove.
Spjald 68
Spurning
In which direction does nonmetallic character generally increase?
Svar
Up and to the right, opposite the general trend in metallic character.
Spjald 69
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Within the same principal shell, which penetrates closer to the nucleus: an s or p orbital?
Svar
An s orbital. Greater penetration means its electrons are less shielded and usually lower in energy than p electrons in the same shell.
Spjald 70
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How do same-charge ion radii generally change down a group?
Svar
They increase as occupied electron shells are added.
Spjald 71
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Which has the higher first ionization energy, P or S?
Svar
P. Its half-filled 3p subshell is relatively stable; S contains a paired 3p orbital that increases repulsion and eases removal.
Spjald 72
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Why should simple periodic-direction rules be used cautiously for transition metals?
Svar
d-electron filling, shielding, oxidation state, and contraction effects make their property changes less regular than main-group trends.
Spjald 73
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Why do periodic-trend statements usually say “generally”?
Svar
Subshell energies, electron pairing, radius definitions, and element-specific configurations create real exceptions to the broad patterns.
Spjald 74
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Which has the larger atomic radius, K or Br?
Svar
K. Both are in Period 4, and atomic radius generally decreases from left to right.
Spjald 75
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Which has the higher first ionization energy, Mg or Cl?
Svar
Cl. Its valence electrons experience greater effective nuclear charge and are held more tightly.
Spjald 76
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Which is more electronegative, Al or Si?
Svar
Si. Electronegativity generally increases across Period 3.
Spjald 77
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Which has the larger atomic radius, O or F?
Svar
O. Atomic radius generally decreases across Period 2.
Spjald 78
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Which has the higher first ionization energy, K or Br?
Svar
Br. First ionization energy generally increases across Period 4.
Spjald 79
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Which is more electronegative, Mg or Cl?
Svar
Cl. It lies farther right in Period 3.
Spjald 80
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Which has the larger atomic radius, Al or Si?
Svar
Al. Atomic radius generally decreases across Period 3 as effective nuclear charge rises.
Spjald 81
Spurning
Which has the higher first ionization energy, O or F?
Svar
F. This pair follows the general increase across Period 2.
Spjald 82
Spurning
Which is more electronegative, K or Br?
Svar
Br. Electronegativity generally increases across Period 4.
Spjald 83
Spurning
Which has the larger atomic radius, Mg or Cl?
Svar
Mg. Both are in Period 3, and Mg lies farther left.
Spjald 84
Spurning
Which has the higher first ionization energy, Al or Si?
Svar
Si. This pair follows the general increase across Period 3.
Spjald 85
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Which is more electronegative, O or F?
Svar
F, the most electronegative element on the Pauling scale.
Spjald 86
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Order Al³⁺, Mg²⁺, Na⁺, Ne, F⁻, and O²⁻ from smallest to largest radius.
Svar
Al³⁺ < Mg²⁺ < Na⁺ < Ne < F⁻ < O²⁻. All have 10 electrons, so radius grows as proton count falls.
Spjald 87
Spurning
Why do upper-right nonmetals usually hold valence electrons tightly?
Svar
Their relatively small radii and high effective nuclear charges create strong attraction between the nucleus and valence electrons.
Spjald 88
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Across a main-group period, what shared cause links smaller radius, higher ionization energy, and higher electronegativity?
Svar
Increasing effective nuclear charge pulls the same-shell valence electrons inward and holds them more strongly.
88 spjöld
Periodic Trends Flashcards: Atomic Radius, Ionization Energy & Electronegativity
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