🧪 General Chemistry I

What you’ll learn

1. Nothing Ever DisappearsState the law of conservation of mass and explain why it means every chemical change is a rearrangement of atoms.A burned log seems to vanish, but its mass leaves as carbon dioxide and water vapor; sealed-vessel experiments show nothing is lost. Lavoisier's precision weighing established that matter is neither created nor destroyed in reactions — chemistry is atoms changing partners, not appearing or disappearing.
2. The Atom, Inside OutDescribe the nuclear model of the atom and explain why the proton count alone fixes an element's identity.Rutherford's gold-foil experiment showed that an atom is mostly empty space around a tiny, dense, positive nucleus of protons and neutrons, orbited by featherweight electrons. The proton count (atomic number) defines the element; varying neutrons gives isotopes like carbon-14.
3. A Map With Blank SquaresExplain how Mendeleev built the periodic table, why its predictive gaps mattered, and how the modern table is organized by atomic number into periods and groups.Sorting elements by weight revealed repeating chemical personalities, which Mendeleev arranged into rows and columns — leaving deliberate gaps whose predicted properties gallium and germanium later matched almost exactly. The modern table orders elements by proton count; rows are periods and columns are families of look-alike elements.
4. Electrons Run the ShowUse electron shells and valence electrons to explain periodic family resemblance and predict which elements are reactive or inert.Electrons fill fixed-capacity shells from the inside out, and only the outermost (valence) electrons take part in chemistry. Columns of the periodic table share a valence count, which is why they share behavior; full shells (noble gases) mean inertness, while nearly full or nearly empty shells mean high reactivity. Flame-test colors are visible evidence of electrons jumping between shells.
5. The Electron HeistExplain how electron transfer creates ions and ionic bonds, and connect the crystal lattice to the properties of ionic compounds.A metal hands its spare valence electrons to a nonmetal, leaving oppositely charged ions whose attraction is the ionic bond. Ions pack into a repeating lattice rather than pairs, which makes ionic compounds hard, brittle, high-melting, and conductive only when the ions are freed by dissolving or melting.
6. Learning to ShareExplain covalent bonding as electron sharing, and trace how water's bent, polar structure produces hydrogen bonding, solvent power, surface tension, and floating ice.When neither atom can take electrons outright, atoms share pairs — covalent bonds — forming discrete molecules like H₂ and H₂O. Oxygen's stronger pull makes water polar, and its bent shape keeps the charges uncanceled, so water molecules cling (hydrogen bonds), dissolve ionic compounds, bead into droplets, and freeze into a spacious hexagonal lattice that floats.
7. Counting by WeighingExplain the mole as a fixed count that links atomic masses to gram quantities, and convert between grams and moles using molar mass.Since atoms can't be counted directly, chemists count by weighing: the mole (6.022 × 10²³ particles) is defined so an element's atomic mass in grams contains exactly one mole of atoms. Molar masses of molecules add up from their atoms, turning any balance into an atom-counting instrument.
8. The Grammar of ChangeWrite and balance chemical equations using coefficients, and interpret the balanced coefficients as mole ratios.A chemical equation is a sentence — reactants, arrow, products — but it must obey conservation of mass: every element's atom count must match across the arrow. Balancing adjusts coefficients (never subscripts, which define substances), and the finished coefficients read directly as mole ratios that scale from single molecules to industrial quantities.
9. Will It React?Classify reactions into the five major families and use the activity series and solubility to predict single- and double-replacement outcomes.Most reactions replay five plots: synthesis, decomposition, single replacement, double replacement, and combustion. The activity series ranks metals by electron-shedding eagerness and predicts which single replacements go; double replacements go when a partner swap produces an insoluble precipitate, like lead iodide's golden rain.
10. Recipe MathUse balanced-equation mole ratios and molar masses to convert between reactant and product masses, and identify the limiting reagent.Stoichiometry is recipe math: convert grams to moles, apply the coefficient ratios, convert back to grams — and conservation of mass audits the answer. When ingredients aren't supplied in recipe proportions, the limiting reagent sets the output, a calculation that ranges from pancakes to the 130 g of sodium azide in an airbag.
11. Heat and the Three Faces of MatterExplain reaction energy as a bond-breaking/bond-forming ledger, and describe states of matter and phase changes in terms of particle motion.Breaking bonds costs energy and forming them releases it; reactions are exothermic or endothermic depending on which side of that ledger wins, with activation energy as the start-up cost. Temperature is particle motion: heating carries a substance from locked solid through sliding liquid to free gas — physical changes with real energy price tags, from geysers to sublimating dry ice.
12. Acids, Bases, and the Power of TenDefine acids and bases by proton transfer, interpret the logarithmic pH scale, and explain neutralization and indicators.Acids donate bare protons (H⁺) and bases accept them; neutralization cancels both into water plus a salt, which is how antacids work. The pH scale measures proton concentration logarithmically — each unit is tenfold — and indicator pigments like litmus and red cabbage make the scale visible in color.

Questions this course answers

Grounded in trusted sources

• OpenStax — Chemistry 2e (2019)
• Brown, LeMay & Bursten — Chemistry: The Central Science, 14th ed. (2018)
• Eric Scerri — The Periodic Table: Its Story and Its Significance (2007)
• Madison Smartt Bell — Lavoisier in the Year One (2005)
• Sam Kean — The Disappearing Spoon (2010)
• John Emsley — Nature's Building Blocks: An A–Z Guide to the Elements (2011)
• NIST — the defined Avogadro constant in the 2019 SI
• Royal Society of Chemistry — periodic table and element data

Every Wunder lesson is built from real, reputable sources — never invented.

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