Chemical and Isotope Data
Back to Portal
Introduction
The ScientificConstants package contains chemical data
Use the GetElement command to access the properties of elements in the Periodic Table . For example, let's review the properties of Platinum (Pt).
withScientificConstants:
GetElementPt
78,symbol=Pt,name=platinum,names=platinum,ionizationenergy=value=8.9587,uncertainty=undefined,units=eV,electronegativity=value=2.28,uncertainty=undefined,units=1,boilingpoint=value=4098.,uncertainty=undefined,units=K,electronaffinity=value=2.128,uncertainty=0.002,units=eV,density=value=21.5,uncertainty=undefined,units=gcm3,atomicweight=value=195.078,uncertainty=0.002,units=amu,meltingpoint=value=2041.55,uncertainty=undefined,units=K
You can also extract the standard atomic weight of platinum.
evalfElementPt, atomicweight,units
3.239348611×10−25kg
With the GetIsotopes command, you can access all instances of platinum.
GetIsotopeselement=Pt
Pt168,Pt169,Pt170,Pt171,Pt172,Pt173,Pt174,Pt175,Pt176,Pt177,Pt178,Pt179,Pt180,Pt181,Pt182,Pt183,Pt184,Pt185,Pt186,Pt187,Pt188,Pt189,Pt190,Pt191,Pt192,Pt193,Pt194,Pt195,Pt196,Pt197,Pt198,Pt199,Pt200,Pt201,Pt202
Example - Molecular Weight
This example determines how many molecules of caffeine are in a 250 gram sample.
The chemical formula for caffeine is C8H12N4O2. Thus, the molecular weight is:
MW ≔ 8⋅ElementC, atomicweight+12⋅ElementH,atomicweight+4⋅ElementN,atomicweight+2⋅ElementO,atomicweight: evalfMW
3.258087476×10−25
which, in the current default system of units, SI, is measured in kilograms (kg). However, molecular weight is typically expressed in atomic mass units (amu). To convert a measurement between units, use theconvert/units function.
MW__AMU≔convertMW, units, kg, amu
MW__AMU≔196.2064800
By definition, the number of atomic mass units per molecule is equal to the number of grams per mole. Hence, divide 250 by the above result.
NumMoles ≔ 250MW__AMU
NumMoles≔1.274167907
which is the number of moles in the sample.
To calculate the number of molecules, multiply the above result by Avogadro's constant.
NumMoles⋅evalfConstantN'A'
7.673218610×1023
Example - Radioactive Decay
The following example shows how to plot the decrease in the radioactive decay activity for a sample of radium-229.
The activity is
Activity ≔ A0⋅ⅇ−λ⋅t:
where, A0 is the initial activity, λ is the mean lifetime of the isotope, and t is the elapsed time.
The mean lifetime is related to the half-life by λ=0.693H
λ ≔ 0.693evalfElementRa229, halflife
λ≔0.002887500000
Plot with A0=1.
A0≔1:plotActivity, t=0..2⋅103, labels=Time (s), Activity, title=Radioactive Decay of Radium-229
Download Help Document
AltStyle によって変換されたページ (->オリジナル) / アドレス: モード: デフォルト 音声ブラウザ ルビ付き 配色反転 文字拡大 モバイル