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