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