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