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.
دربارهٔ این دسته
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.
کارتهای این دسته
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What is a periodic trend?
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A recurring pattern in element properties as atomic number increases across periods and down groups.
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What does covalent radius measure?
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Half the distance between the nuclei of two identical atoms joined by a covalent bond.
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What is first ionization energy?
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The minimum energy needed to remove the most loosely bound electron from an isolated gaseous atom in its ground state.
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What is electronegativity?
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An atom's ability to attract shared electrons toward itself in a chemical bond.
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What is a period on the periodic table?
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A horizontal row. For main-group elements, moving across a period fills orbitals in the same principal electron shell.
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What is ionic radius?
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A measure of an ion's size, usually inferred from distances between ions in crystals.
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What does electron affinity describe?
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The energy change when an electron is added to an isolated gaseous atom to form a gaseous anion.
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What does metallic character describe?
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How readily an element shows metallic behavior, especially losing valence electrons and forming cations.
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What is a group on the periodic table?
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A vertical column. Main-group elements in one group usually share a valence-electron pattern and similar chemistry.
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What is effective nuclear charge?
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The net positive pull an electron feels from the nucleus after shielding and electron–electron repulsion are taken into account.
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What are successive ionization energies?
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The energies needed to remove electrons one after another from the same atom, then from its increasingly positive ions.
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How does electronegativity difference relate to bond polarity?
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A larger difference generally produces a more uneven electron distribution and a more polar bond.
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Why do main-group elements in one group often behave similarly?
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They have the same general number and arrangement of valence electrons, which drive much of their bonding and reactivity.
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What is electron shielding?
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The reduction in nuclear attraction felt by an electron because other electrons lie between it and the nucleus and repel it.
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Why does the definition of ionization energy specify a gaseous atom?
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It isolates the atom from bonding and intermolecular effects, so the energy reflects electron removal from that species itself.
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Where are metals and nonmetals generally found on the periodic table?
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Metals occupy the left and center; nonmetals cluster toward the upper right, with metalloids near the boundary.
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What changes in the electron arrangement across a main-group period?
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Electrons are added to the same principal shell while the nucleus gains one proton from one element to the next.
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How does atomic radius generally change from left to right across a period?
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It decreases.
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How does first ionization energy generally change from left to right across a period?
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It increases, although a few recurring subshell and electron-pairing exceptions interrupt the rise.
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How does electronegativity generally change from left to right across a period?
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It increases for the elements normally assigned electronegativity values.
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What changes in the electron arrangement down a main-group group?
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Each step adds a higher principal electron shell while preserving a similar valence-electron pattern.
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How does atomic radius generally change down a group?
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It increases.
کارت ۲۳
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How does first ionization energy generally change down a group?
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It decreases.
کارت ۲۴
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How does electronegativity generally change down a group?
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It decreases.
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How does effective nuclear charge generally change across a main-group period?
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It increases because nuclear charge rises while added electrons enter the same principal shell and do not fully shield one another.
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How does a cation's radius compare with its neutral parent atom?
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The cation is smaller.
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How does electron addition generally change across a period?
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It generally becomes more energetically favorable toward the right, but electron affinity has substantial exceptions and depends on the sign convention used.
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How does metallic character generally change from left to right across a period?
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It decreases.
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Why are valence electrons generally farther from the nucleus down a group?
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They occupy shells with higher principal quantum numbers, so the electron cloud extends farther outward.
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How does an anion's radius compare with its neutral parent atom?
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The anion is larger.
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How does favorable electron addition generally change down a group?
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It generally becomes less favorable as the added electron enters a larger, more shielded shell, though electron-affinity irregularities are common.
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How does metallic character generally change down a group?
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It increases.
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Why does shielding change less than nuclear charge across a main-group period?
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The added electrons enter the same principal shell, so they do not shield one another as effectively as inner-shell electrons do.
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Which has the larger atomic radius, Li or Na?
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Na. It lies below Li and has an additional occupied electron shell.
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Which has the larger atomic radius, Na or Mg?
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Na. Atomic radius generally decreases from left to right across Period 3.
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How does greater electron–nucleus distance affect electrostatic attraction?
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It weakens the attraction, all else being equal.
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How do successive ionization energies for one element compare?
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Each successive ionization energy is higher than the one before it because an electron is removed from an increasingly positive species.
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Which has the higher first ionization energy, Li or Na?
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Li. Its valence electron is closer to the nucleus and less shielded.
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Which has the higher first ionization energy, Na or Mg?
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Mg. Its greater effective nuclear charge holds the valence electrons more tightly.
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Why does forming a cation usually shrink an atom?
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Electron loss reduces electron–electron repulsion and increases the nuclear pull per remaining electron; losing the outer shell can shrink it sharply.
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Which element is most electronegative on the Pauling scale?
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Fluorine.
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Which is more electronegative, Li or Na?
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Li. Electronegativity generally decreases down Group 1.
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Which is more electronegative, Na or Mg?
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Mg. Electronegativity generally increases across Period 3.
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What does a large jump between successive ionization energies reveal?
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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.
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Why is Cl⁻ larger than neutral Cl?
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The added electron increases repulsion within the valence shell while the nuclear charge stays the same.
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How do you compare the radii of isoelectronic species?
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The species with more protons is smaller because the same number of electrons feels a stronger nuclear attraction.
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Why does an atom have no single sharp physical radius?
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Its electron cloud has no hard edge, so atomic size depends on a defined measurement such as covalent, metallic, or van der Waals radius.
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Why are noble-gas electronegativities often omitted in introductory tables?
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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.
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Why does forming an anion usually expand an atom?
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The extra electron increases electron–electron repulsion and lowers the nuclear pull available per electron.
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Order O²⁻, F⁻, and Ne from largest to smallest radius.
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O²⁻ > F⁻ > Ne. All have 10 electrons, and increasing proton count pulls that electron cloud inward.
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After which removal does Na show its first large ionization-energy jump?
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After the first electron. Removing one valence electron leaves a stable core, so the second removal reaches that core.
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Does electronegativity difference create a universal ionic-versus-covalent cutoff?
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No. A larger difference usually means more bond polarity, but bonding lies on a continuum and context matters.
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How do noble gases generally differ from halogens in electron affinity?
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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.
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Which is smaller, Na⁺ or Mg²⁺?
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Mg²⁺. Both have 10 electrons, but Mg²⁺ has one more proton.
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After which removal does Mg show its first large ionization-energy jump?
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After the second electron. Mg has two valence electrons, so the third removal reaches a core shell.
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How does electronegativity differ from electron affinity?
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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.
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How are atomic radius and first ionization energy generally related?
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A larger radius usually means a lower first ionization energy because the valence electron is farther from the nucleus and easier to remove.
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Which has the more exothermic first electron affinity, F or Cl?
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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.
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Which has the higher first ionization energy, Be or B?
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Be. B loses a higher-energy 2p electron, while Be loses a more penetrating 2s electron from a filled 2s subshell.
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Why does Group 1 metal reactivity generally increase down the group?
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The valence electron is farther out and more shielded, so its first ionization energy falls and electron loss becomes easier.
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How are atomic radius and electronegativity generally related?
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Smaller atoms usually attract bonding electrons more strongly, so electronegativity tends to rise as radius falls.
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Why is Na⁺ much smaller than neutral Na?
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Na loses its entire third-shell valence level, leaving the smaller neon-like electron configuration.
کارت ۶۳
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Which has the higher first ionization energy, Mg or Al?
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Mg. Al's removed electron is a higher-energy 3p electron, while Mg loses a more penetrating 3s electron from a filled 3s subshell.
کارت ۶۴
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Why does halogen reactivity generally decrease down Group 17?
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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.
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Why do Groups 2 and 15 often interrupt the simple electron-affinity trend?
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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.
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Can ion charge alone rank two unrelated ionic radii?
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No. Shell number, electron count, proton count, oxidation state, and crystal environment can all matter; the isoelectronic rule needs the same electron count.
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Which has the higher first ionization energy, N or O?
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N. Its half-filled 2p subshell is relatively stable; O has one paired 2p orbital, and repulsion makes one electron easier to remove.
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In which direction does nonmetallic character generally increase?
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Up and to the right, opposite the general trend in metallic character.
کارت ۶۹
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Within the same principal shell, which penetrates closer to the nucleus: an s or p orbital?
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An s orbital. Greater penetration means its electrons are less shielded and usually lower in energy than p electrons in the same shell.
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How do same-charge ion radii generally change down a group?
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They increase as occupied electron shells are added.
کارت ۷۱
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Which has the higher first ionization energy, P or S?
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P. Its half-filled 3p subshell is relatively stable; S contains a paired 3p orbital that increases repulsion and eases removal.
کارت ۷۲
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Why should simple periodic-direction rules be used cautiously for transition metals?
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d-electron filling, shielding, oxidation state, and contraction effects make their property changes less regular than main-group trends.
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Why do periodic-trend statements usually say “generally”?
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Subshell energies, electron pairing, radius definitions, and element-specific configurations create real exceptions to the broad patterns.
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Which has the larger atomic radius, K or Br?
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K. Both are in Period 4, and atomic radius generally decreases from left to right.
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Which has the higher first ionization energy, Mg or Cl?
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Cl. Its valence electrons experience greater effective nuclear charge and are held more tightly.
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Which is more electronegative, Al or Si?
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Si. Electronegativity generally increases across Period 3.
کارت ۷۷
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Which has the larger atomic radius, O or F?
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O. Atomic radius generally decreases across Period 2.
کارت ۷۸
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Which has the higher first ionization energy, K or Br?
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Br. First ionization energy generally increases across Period 4.
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Which is more electronegative, Mg or Cl?
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Cl. It lies farther right in Period 3.
کارت ۸۰
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Which has the larger atomic radius, Al or Si?
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Al. Atomic radius generally decreases across Period 3 as effective nuclear charge rises.
کارت ۸۱
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Which has the higher first ionization energy, O or F?
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F. This pair follows the general increase across Period 2.
کارت ۸۲
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Which is more electronegative, K or Br?
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Br. Electronegativity generally increases across Period 4.
کارت ۸۳
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Which has the larger atomic radius, Mg or Cl?
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Mg. Both are in Period 3, and Mg lies farther left.
کارت ۸۴
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Which has the higher first ionization energy, Al or Si?
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Si. This pair follows the general increase across Period 3.
کارت ۸۵
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Which is more electronegative, O or F?
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F, the most electronegative element on the Pauling scale.
کارت ۸۶
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Order Al³⁺, Mg²⁺, Na⁺, Ne, F⁻, and O²⁻ from smallest to largest radius.
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Al³⁺ < Mg²⁺ < Na⁺ < Ne < F⁻ < O²⁻. All have 10 electrons, so radius grows as proton count falls.
کارت ۸۷
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Why do upper-right nonmetals usually hold valence electrons tightly?
پاسخ
Their relatively small radii and high effective nuclear charges create strong attraction between the nucleus and valence electrons.
کارت ۸۸
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Across a main-group period, what shared cause links smaller radius, higher ionization energy, and higher electronegativity?
پاسخ
Increasing effective nuclear charge pulls the same-shell valence electrons inward and holds them more strongly.
۸۸ کارت
Periodic Trends Flashcards: Atomic Radius, Ionization Energy & Electronegativity
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