Chemistery

Burn a piece of toast, watch iron rust, mix vinegar and baking soda until it fizzes — something new appears each time. That "something new" is the signature of a chemical reaction, and once you know what's really happening at the atom level, chemistry stops feeling like magic. The short answer: a chemical reaction is a process in which one or more substances (the reactants ) are turned into one or more new substances (the products ) by breaking and re-forming chemical bonds. The atoms themselves aren't created or destroyed — they're just rearranged into new combinations, which is why the total mass stays the same. What actually happens in a reaction Every substance is made of atoms held together by bonds . In a chemical reaction, three things happen in order: Old bonds break in the reactants. Atoms rearrange into new partnerships. New bonds form , giving you the products. Think of it like LEGO. You start with two built models (reactants), pull some b...

Ask any organic chemistry student what finally made substitution and elimination click, and odds are they'll point to a chart like this one. Four mechanisms, two questions, one page. This is the classic Chemistery comparison chart — the one that's lived inside orgo binders since 2015 — redrawn cleaner, tighter, and free to print. The short answer: every one of the four mechanisms is named by two questions. Does a nucleophile attack the carbon (substitution, the "SN") or does a base remove a β-hydrogen (elimination, the "E")? And does it all happen in one concerted step (bimolecular — the "2") or in two steps through a carbocation (unimolecular — the "1")? Answer both and the mechanism names itself: SN1, SN2, E1 or E2. The remastered SN1 · SN2 · E1 · E2 chart. Click it for full size — or grab the printable PDF below and tape it inside your binder. ⏰ Take the chart with you. The remastered chart is a free, printable five-minute sheet ...

Both hold molecules together from the outside, both are far weaker than a real bond — so why does one get a special name? Hydrogen bonds and van der Waals forces sit in the same family, but the gap in strength between them explains some of chemistry's biggest surprises, like why water boils at 100 °C when it "should" boil far colder. The short answer: van der Waals forces are the weak, general attractions between molecules — mainly London dispersion forces and dipole–dipole forces . A hydrogen bond is a much stronger, special attraction that forms only when hydrogen is bonded to nitrogen, oxygen, or fluorine and is drawn to a lone pair on an N, O, or F in another molecule. Both are intermolecular forces; the hydrogen bond is just the strongest of the group. Quick comparison at a glance Feature Van der Waals forces Hydrogen bonds What they include London dispersion + dipole–dipole A special, strong dipole–dipole case Where they occur Between all mo...

You've met ionic bonds (electrons transferred) and covalent bonds (electrons shared). But what holds a lump of pure copper or iron together, when there's only one kind of atom and nobody to trade with? That's the job of the third great bond type: metallic bonding . The short answer: metallic bonding is the attraction between positively charged metal ions and a " sea " of shared, freely moving electrons. Metal atoms give up their outer (valence) electrons into a common pool that flows through the whole structure, and the electrostatic pull between the fixed positive ions and this mobile electron sea holds the metal together. What metallic bonding actually is Picture a metal as a neat 3D lattice of positive ions (metal atoms that have released their valence electrons) sitting in a shared pool of those delocalised electrons . "Delocalised" means the electrons don't belong to any single atom — they roam freely across the entire piece of metal. The...

You've drawn double bonds as two lines and triple bonds as three — but are those lines all the same? They're not. A double bond is really two different kinds of bond stacked together, and knowing the difference explains everything from bond strength to why some molecules can't twist. The short answer: a sigma (σ) bond forms when two orbitals overlap end-to-end , concentrating the shared electrons directly along the line between the two nuclei. A pi (π) bond forms when two p orbitals overlap side-by-side , placing electron density above and below that line. Every single bond is one sigma bond; double and triple bonds add pi bonds on top. Quick comparison at a glance Feature Sigma (σ) bond Pi (π) bond Orbital overlap End-to-end (head-on) Side-by-side (parallel p orbitals) Where the electrons sit Directly between the nuclei Above and below the bond axis Relative strength Stronger (more overlap) Weaker (less overlap) Rotation around the bond Fr...

Here's a puzzle that catches almost everyone: water (H₂O) is polar, but carbon dioxide (CO₂) is not — even though both are built from polar bonds. The answer isn't in the bonds at all. It's in the shape. The short answer: a polar molecule is one with an overall (net) separation of charge — a slightly positive end and a slightly negative end. That happens when a molecule has polar bonds and a shape lopsided enough that those bond dipoles don't cancel out. If the shape is symmetric and the pulls cancel, the molecule is nonpolar even with polar bonds. What "polar molecule" actually means Every polar bond has a little arrow of charge called a dipole , pointing from the δ+ atom toward the δ− atom. A molecule can have several of these arrows at once. To find the molecule's overall polarity, you add the arrows up like tug-of-war teams pulling in different directions: If the arrows cancel (equal and opposite), there's no net pull → nonpolar molecu...