Tech-dat/chemistry-dat/chemistry-dat.md
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# chemistry-dat
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+- [[chemistry-dat]] - [[periodic-table-dat]]
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+
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+
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+
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+
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- [[PCB-cleaner-dat]]
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- [[battery-leakage-dat]]
Tech-dat/chemistry-dat/periodic-table-dat/periodic-table-dat.md
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+# periodic-table-dat
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+- [[chemistry-dat]] - [[periodic-table-dat]]
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+
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+| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 |
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+|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|
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+| 1 H | 2 He | | | | | | | | | | | | | | | | |
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+| 3 Li | 4 Be | 5 B | 6 C | 7 N | 8 O | 9 F | 10 Ne | | | | | | | | | | |
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+| 11 Na | 12 Mg | 13 Al | 14 Si | 15 P | 16 S | 17 Cl | 18 Ar | | | | | | | | | | |
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+| 19 K | 20 Ca | 21 Sc | 22 Ti | 23 V | 24 Cr | 25 Mn | 26 Fe | 27 Co | 28 Ni | 29 Cu | 30 Zn | 31 Ga | 32 Ge | 33 As | 34 Se | 35 Br | 36 Kr |
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+| 37 Rb | 38 Sr | 39 Y | 40 Zr | 41 Nb | 42 Mo | 43 Tc | 44 Ru | 45 Rh | 46 Pd | 47 Ag | 48 Cd | 49 In | 50 Sn | 51 Sb | 52 Te | 53 I | 54 Xe |
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+| 55 Cs | 56 Ba | 57-71* | 72 Hf | 73 Ta | 74 W | 75 Re | 76 Os | 77 Ir | 78 Pt | 79 Au | 80 Hg | 81 Tl | 82 Pb | 83 Bi | 84 Po | 85 At | 86 Rn |
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+| 87 Fr | 88 Ra | 89-103* | 104 Rf | 105 Db | 106 Sg | 107 Bh | 108 Hs | 109 Mt | 110 Ds | 111 Rg | 112 Cn | 113 Nh | 114 Fl | 115 Mc | 116 Lv | 117 Ts | 118 Og |
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+
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+*Lanthanides (La 57–71):
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+| 57 La | 58 Ce | 59 Pr | 60 Nd | 61 Pm | 62 Sm | 63 Eu | 64 Gd | 65 Tb | 66 Dy | 67 Ho | 68 Er | 69 Tm | 70 Yb | 71 Lu |
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+
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+*Actinides (Ac 89–103):
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+| 89 Ac | 90 Th | 91 Pa | 92 U | 93 Np | 94 Pu | 95 Am | 96 Cm | 97 Bk | 98 Cf | 99 Es | 100 Fm | 101 Md | 102 No | 103 Lr |
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+
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+---
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+
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+## Element symbols with English names
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+
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+- H: Hydrogen
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+- He: Helium
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+- Li: Lithium
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+- Be: Beryllium
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+- B: Boron
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+- C: Carbon
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+- N: Nitrogen
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+- O: Oxygen
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+- F: Fluorine
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+- Ne: Neon
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+- Na: Sodium
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+- Mg: Magnesium
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+- Al: Aluminum
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+- Si: Silicon
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+- P: Phosphorus
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+- S: Sulfur
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+- Cl: Chlorine
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+- Ar: Argon
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+- K: Potassium
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+- Ca: Calcium
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+- Sc: Scandium
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+- Ti: Titanium
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+- V: Vanadium
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+- Cr: Chromium
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+- Mn: Manganese
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+- Fe: Iron
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+- Co: Cobalt
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+- Ni: Nickel
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+- Cu: Copper
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+- Zn: Zinc
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+- Ga: Gallium
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+- Ge: Germanium
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+- As: Arsenic
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+- Se: Selenium
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+- Br: Bromine
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+- Kr: Krypton
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+- Rb: Rubidium
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+- Sr: Strontium
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+- Y: Yttrium
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+- Zr: Zirconium
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+- Nb: Niobium
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+- Mo: Molybdenum
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+- Tc: Technetium
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+- Ru: Ruthenium
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+- Rh: Rhodium
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+- Pd: Palladium
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+- Ag: Silver
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+- Cd: Cadmium
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+- In: Indium
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+- Sn: Tin
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+- Sb: Antimony
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+- Te: Tellurium
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+- I: Iodine
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+- Xe: Xenon
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+- Cs: Cesium
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+- Ba: Barium
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+- La: Lanthanum
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+- Ce: Cerium
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+- Pr: Praseodymium
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+- Nd: Neodymium
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+- Pm: Promethium
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+- Sm: Samarium
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+- Eu: Europium
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+- Gd: Gadolinium
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+- Tb: Terbium
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+- Dy: Dysprosium
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+- Ho: Holmium
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+- Er: Erbium
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+- Tm: Thulium
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+- Yb: Ytterbium
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+- Lu: Lutetium
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+- Hf: Hafnium
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+- Ta: Tantalum
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+- W: Tungsten
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+- Re: Rhenium
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+- Os: Osmium
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+- Ir: Iridium
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+- Pt: Platinum
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+- Au: Gold
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+- Hg: Mercury
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+- Tl: Thallium
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+- Pb: Lead
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+- Bi: Bismuth
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+- Po: Polonium
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+- At: Astatine
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+- Rn: Radon
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+- Fr: Francium
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+- Ra: Radium
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+- Ac: Actinium
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+- Th: Thorium
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+- Pa: Protactinium
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+- U: Uranium
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+- Np: Neptunium
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+- Pu: Plutonium
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+- Am: Americium
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+- Cm: Curium
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+- Bk: Berkelium
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+- Cf: Californium
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+- Es: Einsteinium
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+- Fm: Fermium
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+- Md: Mendelevium
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+- No: Nobelium
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+- Lr: Lawrencium
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+- Rf: Rutherfordium
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+- Db: Dubnium
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+- Sg: Seaborgium
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+- Bh: Bohrium
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+- Hs: Hassium
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+- Mt: Meitnerium
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+- Ds: Darmstadtium
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+- Rg: Roentgenium
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+- Cn: Copernicium
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+- Nh: Nihonium
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+- Fl: Flerovium
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+- Mc: Moscovium
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+- Lv: Livermorium
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+- Ts: Tennessine
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+- Og: Oganesson
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+
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+
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+## ref
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+
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+- [[chemistry-dat]]
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app-dat/app-dat.md
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## topics
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-- [[home-plant-dat]]
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+- [[home-plant-dat]] - [[ph-tester-dat]]
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- [[Apocalypse-dat]] - [[surveillance-dat]]
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app-dat/home-plant-dat/ph-tester-dat/2026-01-31-19-42-23.png
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app-dat/home-plant-dat/ph-tester-dat/ph-tester-dat.md
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# ph-tester-dat
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- [[home-plant-dat]] - [[full-spectrum-light-dat]] - [[ph-tester-dat]]
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- Ibias >50 pA → no
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-## ref
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+
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+## probes
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+| Feature / Observation | White / Clear Probe | Grey / Duller Probe |
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+| ------------------------- | ------------------------------- | ---------------------------------- |
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+| Typical role | pH sensing electrode | Reference electrode |
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+| Sensitive to pH | Yes | No |
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+| Voltage behavior | Changes ~59 mV per pH (25 °C) | Nearly constant |
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+| Tip appearance | Clear to milky white glass | Grey / matte ceramic or dull glass |
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+| Internal element | Ag/AgCl + fixed pH solution | Ag/AgCl + KCl electrolyte |
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+| Purpose | Converts H⁺ activity to voltage | Provides stable reference voltage |
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+| Reaction to buffer change | Voltage shifts with pH | Minimal change |
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+| Use with ADC | Must be buffered (ultra-high Z) | Must be buffered (ultra-high Z) |
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+| What happens if swapped | pH reading flips sign | pH reading collapses or drifts |
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+| Can be used alone | No | No |
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+| Common mistake | Connected directly to ADC | Used as sensing electrode |
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+![](2026-01-31-19-42-23.png)
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+Electrode Function
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+Sensing electrode Detects H⁺ ion concentration (pH) in soil water or moisture. Usually made from special glass or ISFET.
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+Reference electrode Provides a stable, fixed voltage to compare against. Usually Ag/AgCl or a solid-state equivalent embedded in the probe.
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+ISFET = 离子敏感场效应晶体管
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+## Simplified probes
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+### 1) Basic principle
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+pH measurement depends on the activity of H+ ions, which produces a potential difference. Traditional pH probes use:
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+- A glass membrane: selective to H+ ions
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+- A reference electrode: provides a stable reference potential
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+If you instead use metal rods or metal-coated probes, the measured potential difference will depend on the metals and the solution composition. In this case you are not measuring true pH but rather a relative ORP (oxidation-reduction potential) or a trend in acidity/alkalinity.
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+Limitations:
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+- Very low accuracy (±1–2 pH or worse)
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+- Can only indicate "acidic vs alkaline" trend, not precise pH
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+- Electrodes oxidize or become contaminated easily; short lifetime
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+
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+### 2) Example metal combinations
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+| Anode (positive) | Cathode (negative) | Notes |
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+| ---------------- | ------------------ | -------------------------------------------------- |
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+| Platinum (Pt) | Ag / AgCl coating | Closest to lab ORP electrodes; corrosion resistant |
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+| Copper (Cu) | Zinc (Zn) | Shows electrochemical reactions; trends observable |
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+| Nickel (Ni) | Copper (Cu) | Inexpensive but short-lived |
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+
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+Key points:
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+- Use one electrode as a reference (Ag/AgCl preferred for stability)
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+- Use one electrode as the sensing probe (inserted into soil or water)
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+- Adding a small amount of saline improves conductivity
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+
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+### Color-based identification
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+| Electrode color | Common materials | Notes |
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+| --------------- | ---------------------------------------------------------------------- | ---------------------------------------------------------------------------------- |
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+| White / silver | Silver (Ag), silver-plated copper, platinum (Pt), nickel (Ni) | Bright, corrosion-resistant; often used for reference or coated sensing surfaces |
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+| Gray / dark | Lead (Pb), titanium (Ti), stainless steel, zinc (Zn), galvanized metal | Darkens with oxidation; hard; often used for sensing probes or protective housings |
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+
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+### Parallel two-probe operation (side-by-side probes)
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+Typical setup:
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+- One white probe (likely Ag/AgCl or silver-plated)
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+- One gray probe (stainless steel, copper, or platinum)
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+- Insert both into soil or into the sample liquid
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+How it works:
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+- Soil/water contains moisture and dissolved ions (H+, OH-, Na+, Cl-, etc.).
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+- A small electrochemical potential forms between the two metal surfaces, like a tiny battery.
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+- The potential difference depends on metal types, conductivity, and acidity/alkalinity.
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+- Measure the voltage between the two probes with a high-impedance ADC or electrometer. The voltage trend roughly reflects soil acidity/alkalinity.
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+Important: this is not a true pH measurement because the system lacks a glass membrane or ISFET that selectively responds to H+ activity.
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+### Characteristics of side-by-side placement
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+| Feature | Description |
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+| ------------------------- | ----------------------------------------------------------------------------------------------------------- |
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+| Potential difference | Local half-cell potentials form between each metal and the sample, creating a measurable voltage difference |
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+| Soil moisture sensitivity | High moisture → lower resistance → more stable signal. Low moisture → high drift and unstable readings |
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+| Probe spacing | Too close → electrochemical interference. Too far → weaker signal. Optimize spacing for your setup |
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+| Durability | Metals oxidize, especially the non-coated (darker) probe, reducing lifetime |
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+
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+
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+## ref
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+
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+- [[ph-tester]] - [[home-plant]]
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app-dat/medical-devices-dat/medical-devices-dat.md
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+# medical-devices-dat
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+- [[ph-test-dat]]
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