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