KAGAKU is an interactive app for learning how atoms, molecules and reactions work through moving visuals. How electrons fill shells, how bonds form, why molecules have their shapes, what makes reactions fast: ideas that are hard to grasp from textbook pictures become clear when you change the conditions yourself.
Developer: Fuji Bit Inc.
12 simulations in 3 categories:
Atoms & elements:
- Periodic Table: Compare all 118 elements colored by category, block (s, p, d, f) or electronegativity. Tap an element for its details. Pinch to zoom.
- Atomic Structure: Raise the atomic number one step at a time and watch electrons fill the shells in a Bohr model, following real electron configurations (potassium is 2, 8, 8, 1). "Excite" lifts an electron, which gives off light as it falls back.
- Flame Test: Compare the flame colors and emission spectra of lithium, sodium, potassium, calcium, strontium, barium and copper. The photon energy (E = hc/λ) of the main line is shown too.
- Chemical Bonds: Pick two atoms and see ionic, covalent and metallic bonds form. The electronegativity difference gives the ionic character and polarity (δ+ / δ−); ionic bonds show formulas such as MgCl₂ and Al₂O₃.
Molecules & matter:
- Molecular Shapes: See the seven shapes set by electron-pair repulsion (VSEPR) in 3D: H₂O, NH₃, CH₄, CO₂, BF₃, PCl₅, SF₆ and more. Lone pairs and bond angles show why. Drag to rotate.
- Organic Chemistry: Ethanol, acetaldehyde, acetic acid, acetone, methylamine, phenol and more, with the functional group (hydroxy, carboxy, ...) highlighted and its family and properties explained.
- Gas Laws: Choose Boyle's, Charles's or Gay-Lussac's law; the quantity it keeps fixed is locked, and particles plus P–V, V–T or P–T graphs show the relationship. Values use real units: kPa, L and K.
- Changes of State (new): Heat or cool 1 mol of water from ice to steam and watch the heating curve and the molecular arrangement side by side. See why the temperature stops at 0 °C and 100 °C (heats of fusion and vaporization).
Reactions & change:
- Balancing Equations: Change coefficients with + and − until the atoms match on both sides. Bars compare the atoms of each element, and the app tells you whether the ratio is the simplest. Seven reactions.
- Titration & pH: Titrate hydrochloric acid (strong) or acetic acid (weak) with NaOH. See the titration curve, equivalence point and indicator ranges, and whether phenolphthalein, methyl orange or bromothymol blue suits the titration.
- How Batteries Work: Choose two metals from Mg, Zn, Fe, Ni, Pb, Cu and Ag, change the ion concentrations and read the voltage. Potentials come from the Nernst equation, with the negative and positive electrodes and half-reactions shown. The same metal on both sides makes a concentration cell.
- Reaction Rate (new): Watch reactions happen through particle collisions. Change temperature, concentration and catalyst and compare the share of collisions above the activation energy and the product graph.
Features:
- Dark and light themes
- Home screen organized by category, plus an "All modes" list
- Tips and a play button in the control panel
- Results update in real time as you move sliders and choices
- An info sheet with formulas and terms for every simulation
- In landscape and on iPad, the canvas and controls sit side by side
- Supports larger text sizes
- VoiceOver reads out each screen's results (pH, voltage, element details, ...)
- 73 languages including English and Japanese (follows the device language)
- No sign-in; start right away
Price and purchases:
- Price: free
- In-app purchases: none
- Subscriptions: none
- Ads: a Pangle banner ad at the bottom of the screen
The "-raku" education series:
- SUUGAKU: Mathematics
- BUTURAKU: Mechanics
- DENRAKU: Electromagnetism
- HARAKU: Waves
- KORAKU: Optics
- RYORAKU: Quantum mechanics
- KAGAKU: Chemistry
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