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