Electronegativity & bond character · Metallic bonds & pure metals · Alloys · Ionic bonds & ratios · Polyatomic ions · Monoatomic ions · Covalent bonds · Naming with prefixes — 149 cards
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The ability of an atom in a chemical compound to attract the shared electron pair towards itself.
No — it isn't a measurable quantity. It's a relative number on a scale.
The Pauling scale. Fluorine = 4.0, the most electronegative element.
It increases, e.g. Li 1.0 → F 4.0. Atoms get smaller, so the nucleus pulls harder on the bonding electrons.
It decreases, e.g. F 4.0 → Cl 3.0 → Br 2.8 → I 2.5. Atoms get bigger, so the bonding electrons are farther from the nucleus.
High EN means more non-metallic. Low EN means more metallic. So non-metallic character increases across a period, and metallic character increases down a group.
The difference in electronegativity between the two bonded atoms: ΔEN = |EN(A) − EN(B)|. The bigger ΔEN is, the more ionic the bond.
No. Real bonds have partial ionic and partial covalent character. Bond type is a spectrum.
Nonpolar covalent: the pair is shared equally. Examples: H₂, O₂, N₂, F₂, Cl₂ (two identical atoms).
Polar covalent: the pair is still shared, but pulled toward the more electronegative atom. Example: H–F.
Ionic: the electron is effectively transferred. Example: NaCl.
Below ~0.5 → nonpolar covalent · ~0.5–1.7 → polar covalent · above ~1.7 → ionic. beyond NCERT
F is δ− (EN 4.0, pulls the pair toward itself). H is δ+ (EN 2.1).
A partial charge, less than a full +1 or −1, because the electrons are only shifted, not fully transferred.
A measure of how polar a bond is: μ = charge × distance between the charge centres, in debye (D). Polar bonds have one; nonpolar bonds don't.
|0.9 − 3.0| = 2.1 → ionic.
|2.1 − 3.0| = 0.9 → polar covalent, with Cl as δ−.
|1.2 − 3.5| = 2.3 → ionic.
The electrostatic attraction between positive metal ions and the surrounding sea of delocalized electrons. beyond NCERT
A lattice of positive metal ions + a sea of delocalized (mobile) electrons. beyond NCERT
The delocalized electrons are free to move, carrying charge and energy easily. beyond NCERT
Layers of metal ions can slide past each other while the electron sea flows around them, so the bond doesn't break. beyond NCERT
Same reason as malleability — ion layers slide past each other without breaking the metallic bond. beyond NCERT
The free electrons in the electron sea reflect light. beyond NCERT
Lustrous, malleable, ductile, good conductors of heat and electricity, sonorous, generally hard, with high melting points.
Makes a ringing sound when struck (which is why bells are made of metal).
Best: silver and copper. Poor: lead and mercury.
Mercury.
Cut with a knife: sodium, potassium (and lithium). Melt in your palm: gallium and caesium.
The attraction between the metal ions and the electron sea is strong and runs through the whole lattice, so breaking it takes a lot of energy. beyond NCERT
Metallic: positive metal ions in a sea of shared, delocalized electrons (metal + metal). Ionic: electrons are transferred from a metal to a non-metal, and the oppositely charged ions attract in a lattice.
In a metal, layers slide and the electron sea keeps holding them together. In an ionic crystal, shifting a layer brings like charges face to face. They repel, so the crystal cracks. beyond NCERT
Metals have free-moving electrons. In an ionic solid the ions are locked in place, so there are no mobile charges until it's melted or dissolved.
A homogeneous mixture of two or more metals, or a metal and a non-metal.
No — only when melted at high temperature. The hot mixture solidifies into an alloy on cooling.
No.
To get materials that are stronger, more rigid, or more corrosion-resistant than the pure metal.
~80% copper + ~20% zinc.
~80% copper + ~20% tin.
Iron + carbon (0.03–0.8%) + chromium (16–18%) + nickel (10–14%) + molybdenum (2–3%).
A mixture (homogeneous) — no new chemical bond forms between the different metal atoms.
An alloy of lead + tin. It has a low melting point, so it's used to weld electrical wires together.
An alloy in which one of the metals is mercury.
Pure (24-carat) gold is very soft. Alloying it with silver or copper (22 parts gold : 2 parts Cu/Ag) makes it hard enough to wear.
Both are lower. Brass and bronze conduct worse than copper, and solder melts lower than lead or tin.
Pure iron is very soft and stretches easily when hot. A little carbon makes it hard and strong. Adding nickel and chromium gives stainless steel, which doesn't rust.
Atoms of a different size disrupt the neat layers, so the layers can't slide past each other as easily. beyond NCERT
The electrostatic force of attraction between oppositely charged ions that holds them together.
By transfer of electrons, typically from a metal atom to a non-metal atom.
It tends to donate/lose electrons, forming a positive ion (cation).
It tends to gain or share electrons to complete its octet.
It loses its one valence electron.
It gains one electron to complete its octet.
A positively charged ion, formed when an atom loses electrons.
A negatively charged ion, formed when an atom gains electrons.
No — they form 3-D crystal lattices, a repeating pattern of ions.
Six (and each Cl⁻ is surrounded by six Na⁺).
Cation name first, then anion name.
“-ide” — e.g. chloride, oxide, sulfide.
The cation symbol, then the anion symbol, with charges written underneath (not as superscripts).
CaCl₂
Al₂O₃
Mg(OH)₂
When 2 or more of the same polyatomic ion appear in the formula.
No — the ions are locked in the lattice and can't move.
When molten or dissolved in water — the ions become free to move.
Soluble in water; insoluble in kerosene and petrol.
High — due to strong inter-ionic (electrostatic) attraction.
Total positive charge = total negative charge. The compound is electrically neutral overall.
Na₂O. Two Na⁺ are needed to balance one O²⁻.
MgO. Criss-cross gives Mg₂O₂; simplify to the lowest ratio, 1 : 1.
FeCl₃
An ion formed from two or more atoms bonded together, carrying one overall charge.
No — unlike simple monoatomic anions.
OH⁻, valency 1
NO₃⁻, valency 1
HCO₃⁻, valency 1
CO₃²⁻, valency 2
SO₄²⁻, valency 2
NH₄⁺, valency 1
Ammonium, NH₄⁺ — all the others are anions.
Covalent bonds. The whole group carries one charge and forms ionic bonds with other ions.
CaOH₂ would mean 1 O and 2 H. The brackets show the whole OH⁻ unit is taken twice.
CaCO₃. The 2+ and 2− balance 1 : 1, so no brackets are needed.
Ca(NO₃)₂
(NH₄)₂SO₄
Al₂(SO₄)₃. 2 × (+3) = +6 balances 3 × (−2) = −6.
Al(OH)₃
NaHCO₃
NH₄Cl
Sodium sulfate; potassium carbonate.
An ion formed from a single atom that has gained or lost electrons.
Na⁺, valency 1
Li⁺, valency 1
K⁺, valency 1
Ag⁺, valency 1
Ca²⁺, valency 2
Ba²⁺, valency 2
Fe²⁺, valency 2
Fe³⁺, valency 3
Cu⁺, valency 1
Cu²⁺, valency 2
Mg²⁺, valency 2
Zn²⁺, valency 2
Al³⁺, valency 3
F⁻, valency 1
Cl⁻, valency 1
Br⁻, valency 1
I⁻, valency 1
O²⁻, valency 2
S²⁻, valency 2
Iron (Fe²⁺ ferrous / Fe³⁺ ferric) and copper (Cu⁺ cuprous / Cu²⁺ cupric).
A bond formed by sharing a pair of electrons between two atoms. Each shared pair is one bond.
Non-metal + non-metal.
Both atoms attract electrons strongly and neither will give one up, so they share to complete their octets.
Atoms tend to lose, gain or share electrons until they have 8 electrons in their outer shell (a noble-gas configuration). Hydrogen aims for 2.
1, 2 and 3 pairs. Single: H₂, Cl₂. Double: O₂. Triple: N₂.
6 (three pairs), e.g. N≡N in N₂.
As separate molecules (H₂O, CO₂, CH₄), unlike the lattice of an ionic compound.
Generally low. The forces between molecules are weak, even though the bonds inside each molecule are strong.
Generally no. They have no ions or free electrons to carry charge (e.g. a sugar solution doesn't conduct).
Metallic: delocalized in a shared sea. Ionic: transferred. Covalent: shared between two specific atoms.
Yes. The electrons are still shared, just unequally.
mono-1 · di-2 · tri-3 · tetra-4 · penta-5 · hexa-6 · hepta-7
tetra- = 4 · hexa- = 6
penta- = 5 · hepta- = 7
Covalent (non-metal + non-metal) only.
The ions' charges already fix the ratio, so the name doesn't need to state it. MgCl₂ = magnesium chloride.
No. CO = carbon monoxide, not "monocarbon monoxide". Mono- is only used on the second element.
-ide: oxide, chloride, sulfide, fluoride.
When a prefix ending in a or o comes before oxide, the vowel drops: mono + oxide → monoxide, penta + oxide → pentoxide, tetra + oxide → tetroxide.
When hydrogen comes first, it gets no prefix: H₂S = hydrogen sulfide, not "dihydrogen sulfide".
H₂O = water, NH₃ = ammonia.
Carbon dioxide
Carbon monoxide
Dinitrogen pentoxide
Dinitrogen tetroxide
Phosphorus trichloride
Phosphorus pentachloride
Sulfur hexafluoride
Carbon tetrachloride
Sulfur trioxide
CS₂
P₂O₅
NO₂
N₂O₃
IF₇
Aluminium oxide. It's ionic (metal + non-metal), so no prefixes. Not "dialuminium trioxide".
Calcium chloride. It's ionic, so no "di-".
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