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