Repository: rsdefever/ele (language: python)

Issue:
Add atomic radii?
I would be OK adding this data at a later point, after an initial release. 


Discussion / hints:
Yeah, it make sense to have these info as it is a standalone package. I think the next step would be finding a way to scrape these info from some NIST or some reliable source. 
Tagging along, I think density info may also be helpful to have (like for `mbuild` `fill_box` function)
> Yeah, it make sense to have these info as it is a standalone package. I think the next step would be finding a way to scrape these info from some NIST or some reliable source.

It should come from NIST. Scraping is best but it may require some by-hand curation as did the mass data. Its not impossible for ~100 elements.

> Tagging along, I think density info may also be helpful to have (like for mbuild `fill_box` function)

I disagree here, the density is not an elemental property, unless you are thinking of an atomic fluid, e.g., argon. Even then density is normally provided to `fill_box`. 
Yup, that's true, I take back that suggestion. 
I'm finally peeking at this package and it is _clean_! 🤩 This might be a good source for empirical atomic radii https://doi.org/10.1063/1.1725697. Or if we want van der Waal's radii, this might be good https://doi.org/10.1039/C3DT50599E. I'd be happy to add either/both in a PR if you like.
@jennyfothergill why do you suggest those sources? I'm not in opposition, I just don't know what would be considered the "gold-standard" data. It's all pretty far out of my area of expertise.

IMO, we only need one set of radii, so I would probably vote for the van der Waals radii. But I would be opening to listening others think we should have more (it looks like `QCElemental` supports covalent radii and van der Waals radii).
@rsdefever I couldn't find a NIST source for atomic radii--I think because there's a lot of variation depending on which radius you consider (VDW, ionic, covalent). I am open to a different source--I just thought those might be useful. :)
@jennyfothergill no I definitely appreciate the suggestions!! The main questions I'm trying to answer for myself are:
* do we need some sort of radii in this package?
* what is the benefit/what will it be used for?
* do the answers to the prior two questions inform what radii should be included?

All open ended. I don't have coherent answers for any of them yet.
If the previous questions (on necessity and usage) are answered, here are some further thoughts. 😉

I recommend naming the property in a way that indicates the definition used (e.g. "van der Waals radius" and not just "radius"). There are some notes about measuring/calculating atomic radii on [this Wikipedia data page](https://en.wikipedia.org/wiki/Atomic_radii_of_the_elements_(data_page)) that may be helpful disclaimers to include in the docs, in addition to listing whatever sources of data are used. 

Here are some notes on how other periodic table packages solve this problem:

### mendeleev
https://mendeleev.readthedocs.io/en/stable/code.html#element
- Includes many properties based on the source, such as `atomic_radius`, `atomic_radius_rahm`, `covalent_radius_bragg`, `covalent_radius_cordero`, `covalent_radius_pyykko`, etc.

### periodictable
https://periodictable.readthedocs.io/en/latest/api/covalent_radius.html
- Uses Cordero for radius (`covalent_radius` property), also includes uncertainty 🤷 (`covalent_radius_uncertainty` property) and units.
- It documents that the `covalent_radius` is the "average atomic radius when bonded to C, N or O."
- It mentions that the CRC uses the average of Cordero and Pyykkö.
I think having some radii property would be excellent (can enable new visualization backends possibly). 

I echo what Bradley said above, as long as the radius term is specifically named and sources are available for the radii and method If necessary. 
Visualization might already be solved, since most software for that kind of thing also has to know the usual [CPK coloring](https://en.wikipedia.org/wiki/CPK_coloring). I assume that radii are already included in packages supporting CPK or similar colors. 😄
+1 to naming what the "radius" actually is, the radius of an atom is very poorly defined.
Given that the MoSDeF focus is primarily soft matter systems, I think the van der Waals radii probably make the most sense. [This]( https://doi.org/10.1039/C3DT50599E) reference (thanks to @jennyfothergill) seems good, and has vdW radii up to atomic number 100.

I've also finally found a good reason to add these; they might be needed for my partial charge module. 
@jennyfothergill did you want to take the lead on this? If not, thats fine, but I want to get this added reasonably soon, so I'll go ahead and do it :). 

Fix patch:
diff --git a/docs/index.md b/docs/index.md
index af1b84f..230a0e8 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -48,7 +48,7 @@ two-character element symbol. If not, it then checks if the string
 matches a full element name. The function returns the matching element.
 If there is no matching element, an `ElementError` is raised.
 
-Each `Element` has four attributes which can be accessed
+Each `Element` has six attributes which can be accessed
 (as demonstrated below for ``na``):
 
 ```python
@@ -58,6 +58,8 @@ na.name
 na.symbol
 na.atomic_number
 na.mass
+na.radius_bondi
+na.radius_alvarez
 ```
 
 The elements can also be accessed by symbol as follows:
diff --git a/docs/sources.md b/docs/sources.md
index 5260468..2f2ed00 100644
--- a/docs/sources.md
+++ b/docs/sources.md
@@ -1,4 +1,4 @@
-## Atomic weights source
+## Atomic weights
 
 Atomic weights of the elements 2013 (IUPAC Technical Report), Juris Meija, Tyler B. Coplen, Michael Berglund, Willi A. Brand, Paul De Bièvre, Manfred Gröning, Norman E. Holden, Johanna Irrgeher, Robert D. Loss, Thomas Walczyk and Thomas Prohaska
 
@@ -20,7 +20,7 @@ The `bibtex` entry for the reference is:
 	      url = "https://www.degruyter.com/view/journals/pac/88/3/article-p265.xml"
 	}
 
-## Details
+### Details
 
 The values for `Element.mass` were taken from the abridged standard atomic weights (Table 2), with the following exceptions:
 
@@ -30,4 +30,63 @@ The values for `Element.mass` were taken from the abridged standard atomic weigh
 These choices follow the convention used for the [NIST periodic table](
 https://www.nist.gov/pml/periodic-table-elements).
 
+## Atomic radius
+We provide two options for the van der Waals radius, the Bondi radii, and the Alvarez
+radii.
+
+### Bondi radii
+
+The values were taken from Tables I and XIV of 1964 paper by Bondi.
+Values for Hg, Cd, and Zn came from Table I of the 1966 paper. 
+
+J. Phys. Chem. 1964; 68(3): 441-451, doi: 10.1021/j100785a001
+
+J. Phys. Chem. 1966; 70(9): 3006-3007, doi: 10.1021/j100881a503
+
+The `bibtex` entries are:
+
+    @article{Bondi:1964:JPhysChem,
+      title={van der Waals volumes and radii},
+      author={Bondi, A van},
+      journal={The Journal of physical chemistry},
+      volume={68},
+      number={3},
+      pages={441--451},
+      year={1964},
+      publisher={ACS Publications}
+    }
+    @article{Bondi:1966:JPhysChem,
+      title={Van der Waals volumes and radii of metals in covalent compounds},
+      author={Bondi, A},
+      journal={The Journal of Physical Chemistry},
+      volume={70},
+      number={9},
+      pages={3006--3007},
+      year={1966},
+      publisher={ACS Publications}
+    }
+
+### Alvarez radii
+
+Values were taken from Table 1.
+
+Dalton Trans. 2013; 42: 8617-8636, doi: 10.1039/C3DT50599E
+
+The `bibtex` entry for the reference is:
+
+    @article{Alvarez:2013:Dalton,
+    author ="Alvarez, Santiago",
+    title  ="A cartography of the van der Waals territories",
+    journal  ="Dalton Trans.",
+    year  ="2013",
+    volume  ="42",
+    issue  ="24",
+    pages  ="8617-8636",
+    publisher  ="The Royal Society of Chemistry",
+    doi  ="10.1039/C3DT50599E",
+    url  ="http://dx.doi.org/10.1039/C3DT50599E",
+    }
+
+
+
 
diff --git a/ele/element.py b/ele/element.py
index aa762f1..7784215 100644
--- a/ele/element.py
+++ b/ele/element.py
@@ -18,7 +18,7 @@
 )
 
 
-class Element(namedtuple("Element", "atomic_number, name, symbol, mass")):
+class Element(namedtuple("Element", "atomic_number, name, symbol, mass, radius_bondi, radius_alvarez")):
     """Chemical element object
 
     Template to create a chemical element.
@@ -258,6 +258,8 @@ def infer_element_from_string(string):
             name=element_properties["name"],
             symbol=element_properties["symbol"],
             mass=element_properties["mass"],
+            radius_bondi=element_properties["radius_bondi"],
+            radius_alvarez=element_properties["radius_alvarez"],
         )
     )
 
diff --git a/ele/lib/README.md b/ele/lib/README.md
index 8081a56..c330332 100644
--- a/ele/lib/README.md
+++ b/ele/lib/README.md
@@ -1,12 +1,12 @@
+A `.bib` file with all the references is provided in this directory.
+
 ## Atomic weights source
 
 Atomic weights of the elements 2013 (IUPAC Technical Report), Juris Meija, Tyler B. Coplen, Michael Berglund, Willi A. Brand, Paul De Bièvre, Manfred Gröning, Norman E. Holden, Johanna Irrgeher, Robert D. Loss, Thomas Walczyk and Thomas Prohaska
 
 Pure Appl. Chem. 2016; 88(3): 265-291, doi: 10.1515/pac-2015-0305
 
-A `.bib` file with the reference is also present in this directory.
-
-## Details
+### Details
 
 The values for `Element.mass` were taken from the abridged standard atomic weights (Table 2), with the following exceptions:
 
@@ -16,4 +16,22 @@ The values for `Element.mass` were taken from the abridged standard atomic weigh
 These choices follow the convention used for the [NIST periodic table](
 https://www.nist.gov/pml/periodic-table-elements).
 
+## Atomic radius
+We provide two options for the van der Waals radius, the Bondi radii, and the Alvarez
+radii.
+
+### Bondi radii
+
+The values were taken from Tables I and XIV of 1964 paper by Bondi.
+Values for Hg, Cd, and Zn came from Table I of the 1966 paper. 
+
+J. Phys. Chem. 1964; 68(3): 441-451, doi: 10.1021/j100785a001
+
+J. Phys. Chem. 1966; 70(9): 3006-3007, doi: 10.1021/j100881a503
+
+
+### Alvarez radii
+
+Values were taken from Table 1.
 
+Dalton Trans. 2013; 42: 8617-8636, doi: 10.1039/C3DT50599E
diff --git a/ele/lib/elements.json b/ele/lib/elements.json
index 318e360..499e30a 100644
--- a/ele/lib/elements.json
+++ b/ele/lib/elements.json
@@ -3,708 +3,944 @@
     "name": "hydrogen",
     "symbol": "H",
     "atomic number": 1,
-    "mass": 1.008
+    "mass": 1.008,
+    "radius_bondi": 1.20,
+    "radius_alvarez": 1.20
   },
   "helium": {
     "name": "helium",
     "symbol": "He",
     "atomic number": 2,
-    "mass": 4.0026
+    "mass": 4.0026,
+    "radius_bondi": 1.40,
+    "radius_alvarez": 1.43
   },
   "lithium": {
     "name": "lithium",
     "symbol": "Li",
     "atomic number": 3,
-    "mass": 6.94
+    "mass": 6.94,
+    "radius_bondi": 1.82,
+    "radius_alvarez": 2.12
   },
   "beryllium": {
     "name": "beryllium",
     "symbol": "Be",
     "atomic number": 4,
-    "mass": 9.0122
+    "mass": 9.0122,
+    "radius_bondi": null,
+    "radius_alvarez": 1.98
   },
   "boron": {
     "name": "boron",
     "symbol": "B",
     "atomic number": 5,
-    "mass": 10.81
+    "mass": 10.81,
+    "radius_bondi": null,
+    "radius_alvarez": 1.91
   },
   "carbon": {
     "name": "carbon",
     "symbol": "C",
     "atomic number": 6,
-    "mass": 12.011
+    "mass": 12.011,
+    "radius_bondi": 1.70,
+    "radius_alvarez": 1.77
   },
   "nitrogen": {
     "name": "nitrogen",
     "symbol": "N",
     "atomic number": 7,
-    "mass": 14.007
+    "mass": 14.007,
+    "radius_bondi": 1.55,
+    "radius_alvarez": 1.66
   },
   "oxygen": {
     "name": "oxygen",
     "symbol": "O",
     "atomic number": 8,
-    "mass": 15.999
+    "mass": 15.999,
+    "radius_bondi": 1.52,
+    "radius_alvarez": 1.50
   },
   "fluorine": {
     "name": "fluorine",
     "symbol": "F",
     "atomic number": 9,
-    "mass": 18.998
+    "mass": 18.998,
+    "radius_bondi": 1.47,
+    "radius_alvarez": 1.46
   },
   "neon": {
     "name": "neon",
     "symbol": "Ne",
     "atomic number": 10,
-    "mass": 20.180
+    "mass": 20.180,
+    "radius_bondi": 1.54,
+    "radius_alvarez": 1.58
   },
   "sodium": {
     "name": "sodium",
     "symbol": "Na",
     "atomic number": 11,
-    "mass": 22.990
+    "mass": 22.990,
+    "radius_bondi": 2.27,
+    "radius_alvarez": 2.50
   },
   "magnesium": {
     "name": "magnesium",
     "symbol": "Mg",
     "atomic number": 12,
-    "mass": 24.305
+    "mass": 24.305,
+    "radius_bondi": 1.73,
+    "radius_alvarez": 2.51
   },
   "aluminum": {
     "name": "aluminum",
     "symbol": "Al",
     "atomic number": 13,
-    "mass": 26.982
+    "mass": 26.982,
+    "radius_bondi": null,
+    "radius_alvarez": 2.25
   },
   "silicon": {
     "name": "silicon",
     "symbol": "Si",
     "atomic number": 14,
-    "mass": 28.085
+    "mass": 28.085,
+    "radius_bondi": 2.10,
+    "radius_alvarez": 2.19
   },
   "phosphorus": {
     "name": "phosphorus",
     "symbol": "P",
     "atomic number": 15,
-    "mass": 30.974
+    "mass": 30.974,
+    "radius_bondi": 1.80,
+    "radius_alvarez": 1.90
   },
   "sulfur": {
     "name": "sulfur",
     "symbol": "S",
     "atomic number": 16,
-    "mass": 32.06
+    "mass": 32.06,
+    "radius_bondi": 1.80,
+    "radius_alvarez": 1.89
   },
   "chlorine": {
     "name": "chlorine",
     "symbol": "Cl",
     "atomic number": 17,
-    "mass": 35.45
+    "mass": 35.45,
+    "radius_bondi": 1.75,
+    "radius_alvarez": 1.82
   },
   "argon": {
     "name": "argon",
     "symbol": "Ar",
     "atomic number": 18,
-    "mass": 39.948
+    "mass": 39.948,
+    "radius_bondi": 1.88,
+    "radius_alvarez": 1.83
   },
   "potassium": {
     "name": "potassium",
     "symbol": "K",
     "atomic number": 19,
-    "mass": 39.098
+    "mass": 39.098,
+    "radius_bondi": 2.75,
+    "radius_alvarez": 2.73
   },
   "calcium": {
     "name": "calcium",
     "symbol": "Ca",
     "atomic number": 20,
-    "mass": 40.078
+    "mass": 40.078,
+    "radius_bondi": null,
+    "radius_alvarez": 2.62
   },
   "scandium": {
     "name": "scandium",
     "symbol": "Sc",
     "atomic number": 21,
-    "mass": 44.956
+    "mass": 44.956,
+    "radius_bondi": null,
+    "radius_alvarez": 2.58
   },
   "titanium": {
     "name": "titanium",
     "symbol": "Ti",
     "atomic number": 22,
-    "mass": 47.867
+    "mass": 47.867,
+    "radius_bondi": null,
+    "radius_alvarez": 2.46
   },
   "vanadium": {
     "name": "vanadium",
     "symbol": "V",
     "atomic number": 23,
-    "mass": 50.942
+    "mass": 50.942,
+    "radius_bondi": null,
+    "radius_alvarez": 2.42
   },
   "chromium": {
     "name": "chromium",
     "symbol": "Cr",
     "atomic number": 24,
-    "mass": 51.996
+    "mass": 51.996,
+    "radius_bondi": null,
+    "radius_alvarez": 2.45
   },
   "manganese": {
     "name": "manganese",
     "symbol": "Mn",
     "atomic number": 25,
-    "mass": 54.938
+    "mass": 54.938,
+    "radius_bondi": null,
+    "radius_alvarez": 2.45
   },
   "iron": {
     "name": "iron",
     "symbol": "Fe",
     "atomic number": 26,
-    "mass": 55.845
+    "mass": 55.845,
+    "radius_bondi": null,
+    "radius_alvarez": 2.44
   },
   "cobalt": {
     "name": "cobalt",
     "symbol": "Co",
     "atomic number": 27,
-    "mass": 58.933
+    "mass": 58.933,
+    "radius_bondi": null,
+    "radius_alvarez": 2.40
   },
   "nickel": {
     "name": "nickel",
     "symbol": "Ni",
     "atomic number": 28,
-    "mass": 58.693
+    "mass": 58.693,
+    "radius_bondi": 1.63,
+    "radius_alvarez": 2.40
   },
   "copper": {
     "name": "copper",
     "symbol": "Cu",
     "atomic number": 29,
-    "mass": 63.546
+    "mass": 63.546,
+    "radius_bondi": 1.4,
+    "radius_alvarez": 2.38
   },
   "zinc": {
     "name": "zinc",
     "symbol": "Zn",
     "atomic number": 30,
-    "mass": 65.38
+    "mass": 65.38,
+    "radius_bondi": 1.39,
+    "radius_alvarez": 2.39
   },
   "gallium": {
     "name": "gallium",
     "symbol": "Ga",
     "atomic number": 31,
-    "mass": 69.723
+    "mass": 69.723,
+    "radius_bondi": 1.87,
+    "radius_alvarez": 2.32
   },
   "germanium": {
     "name": "germanium",
     "symbol": "Ge",
     "atomic number": 32,
-    "mass": 72.630
+    "mass": 72.630,
+    "radius_bondi": null,
+    "radius_alvarez": 2.29
   },
   "arsenic": {
     "name": "arsenic",
     "symbol": "As",
     "atomic number": 33,
-    "mass": 74.922
+    "mass": 74.922,
+    "radius_bondi": 1.85,
+    "radius_alvarez": 1.88
   },
   "selenium": {
     "name": "selenium",
     "symbol": "Se",
     "atomic number": 34,
-    "mass": 78.971
+    "mass": 78.971,
+    "radius_bondi": 1.90,
+    "radius_alvarez": 1.82
   },
   "bromine": {
     "name": "bromine",
     "symbol": "Br",
     "atomic number": 35,
-    "mass": 79.904
+    "mass": 79.904,
+    "radius_bondi": 1.85,
+    "radius_alvarez": 1.86
   },
   "krypton": {
     "name": "krypton",
     "symbol": "Kr",
     "atomic number": 36,
-    "mass": 83.798
+    "mass": 83.798,
+    "radius_bondi": 2.02,
+    "radius_alvarez": 2.25
   },
   "rubidium": {
     "name": "rubidium",
     "symbol": "Rb",
     "atomic number": 37,
-    "mass": 85.468
+    "mass": 85.468,
+    "radius_bondi": null,
+    "radius_alvarez": 3.21
   },
   "strontium": {
     "name": "strontium",
     "symbol": "Sr",
     "atomic number": 38,
-    "mass": 87.62
+    "mass": 87.62,
+    "radius_bondi": null,
+    "radius_alvarez": 2.84
   },
   "yttrium": {
     "name": "yttrium",
     "symbol": "Y",
     "atomic number": 39,
-    "mass": 88.906
+    "mass": 88.906,
+    "radius_bondi": null,
+    "radius_alvarez": 2.75
   },
   "zirconium": {
     "name": "zirconium",
     "symbol": "Zr",
     "atomic number": 40,
-    "mass": 91.224
+    "mass": 91.224,
+    "radius_bondi": null,
+    "radius_alvarez": 2.52
   },
   "niobium": {
     "name": "niobium",
     "symbol": "Nb",
     "atomic number": 41,
-    "mass": 92.906
+    "mass": 92.906,
+    "radius_bondi": null,
+    "radius_alvarez": 2.56
   },
   "molybdenum": {
     "name": "molybdenum",
     "symbol": "Mo",
     "atomic number": 42,
-    "mass": 95.95
+    "mass": 95.95,
+    "radius_bondi": null,
+    "radius_alvarez": 2.45
   },
   "technetium": {
     "name": "technetium",
     "symbol": "Tc",
     "atomic number": 43,
-    "mass": 97.0
+    "mass": 97.0,
+    "radius_bondi": null,
+    "radius_alvarez": 2.44
   },
   "ruthenium": {
     "name": "ruthenium",
     "symbol": "Ru",
     "atomic number": 44,
-    "mass": 101.07
+    "mass": 101.07,
+    "radius_bondi": null,
+    "radius_alvarez": 2.46
   },
   "rhodium": {
     "name": "rhodium",
     "symbol": "Rh",
     "atomic number": 45,
-    "mass": 102.91
+    "mass": 102.91,
+    "radius_bondi":  null,
+    "radius_alvarez": 2.44
   },
   "palladium": {
     "name": "palladium",
     "symbol": "Pd",
     "atomic number": 46,
-    "mass": 106.42
+    "mass": 106.42,
+    "radius_bondi": 1.63,
+    "radius_alvarez": 2.15
   },
   "silver": {
     "name": "silver",
     "symbol": "Ag",
     "atomic number": 47,
-    "mass": 107.87
+    "mass": 107.87,
+    "radius_bondi": 1.72,
+    "radius_alvarez": 2.53
   },
   "cadmium": {
     "name": "cadmium",
     "symbol": "Cd",
     "atomic number": 48,
-    "mass": 112.41
+    "mass": 112.41,
+    "radius_bondi": 1.62,
+    "radius_alvarez": 2.49
   },
   "indium": {
     "name": "indium",
     "symbol": "In",
     "atomic number": 49,
-    "mass": 114.82
+    "mass": 114.82,
+    "radius_bondi": 1.93,
+    "radius_alvarez": 2.43
   },
   "tin": {
     "name": "tin",
     "symbol": "Sn",
     "atomic number": 50,
-    "mass": 118.71
+    "mass": 118.71,
+    "radius_bondi": 2.17,
+    "radius_alvarez": 2.42
   },
   "antimony": {
     "name": "antimony",
     "symbol": "Sb",
     "atomic number": 51,
-    "mass": 121.76
+    "mass": 121.76,
+    "radius_bondi": null,
+    "radius_alvarez": 2.47
   },
   "tellurium": {
     "name": "tellurium",
     "symbol": "Te",
     "atomic number": 52,
-    "mass": 127.60
+    "mass": 127.60,
+    "radius_bondi": 2.06,
+    "radius_alvarez": 1.99
   },
   "iodine": {
     "name": "iodine",
     "symbol": "I",
     "atomic number": 53,
-    "mass": 126.90
+    "mass": 126.90,
+    "radius_bondi": 1.98,
+    "radius_alvarez": 2.04
   },
   "xenon": {
     "name": "xenon",
     "symbol": "Xe",
     "atomic number": 54,
-    "mass": 131.29
+    "mass": 131.29,
+    "radius_bondi": 2.16,
+    "radius_alvarez": 2.06
   },
   "cesium": {
     "name": "cesium",
     "symbol": "Cs",
     "atomic number": 55,
-    "mass": 132.91
+    "mass": 132.91,
+    "radius_bondi": null,
+    "radius_alvarez": 3.48
   },
   "barium": {
     "name": "barium",
     "symbol": "Ba",
     "atomic number": 56,
-    "mass": 137.33
+    "mass": 137.33,
+    "radius_bondi": null,
+    "radius_alvarez": 3.03
   },
   "lanthanum": {
     "name": "lanthanum",
     "symbol": "La",
     "atomic number": 57,
-    "mass": 138.91
+    "mass": 138.91,
+    "radius_bondi": null,
+    "radius_alvarez": 2.98
   },
   "cerium": {
     "name": "cerium",
     "symbol": "Ce",
     "atomic number": 58,
-    "mass": 140.12
+    "mass": 140.12,
+    "radius_bondi": null,
+    "radius_alvarez": 2.88
   },
   "praseodymium": {
     "name": "praseodymium",
     "symbol": "Pr",
     "atomic number": 59,
-    "mass": 140.91
+    "mass": 140.91,
+    "radius_bondi": null,
+    "radius_alvarez": 2.92
   },
   "neodymium": {
     "name": "neodymium",
     "symbol": "Nd",
     "atomic number": 60,
-    "mass": 144.24
+    "mass": 144.24,
+    "radius_bondi": null,
+    "radius_alvarez": 2.95
   },
   "promethium": {
     "name": "promethium",
     "symbol": "Pm",
     "atomic number": 61,
-    "mass": 145.0
+    "mass": 145.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "samarium": {
     "name": "samarium",
     "symbol": "Sm",
     "atomic number": 62,
-    "mass": 150.36
+    "mass": 150.36,
+    "radius_bondi": null,
+    "radius_alvarez": 2.90
   },
   "europium": {
     "name": "europium",
     "symbol": "Eu",
     "atomic number": 63,
-    "mass": 151.96
+    "mass": 151.96,
+    "radius_bondi": null,
+    "radius_alvarez": 2.87
   },
   "gadolinium": {
     "name": "gadolinium",
     "symbol": "Gd",
     "atomic number": 64,
-    "mass": 157.25
+    "mass": 157.25,
+    "radius_bondi": null,
+    "radius_alvarez": 2.83
   },
   "terbium": {
     "name": "terbium",
     "symbol": "Tb",
     "atomic number": 65,
-    "mass": 158.93
+    "mass": 158.93,
+    "radius_bondi": null,
+    "radius_alvarez": 2.79
   },
   "dysprosium": {
     "name": "dysprosium",
     "symbol": "Dy",
     "atomic number": 66,
-    "mass": 162.50
+    "mass": 162.50,
+    "radius_bondi": null,
+    "radius_alvarez": 2.87
   },
   "holmium": {
     "name": "holmium",
     "symbol": "Ho",
     "atomic number": 67,
-    "mass": 164.93
+    "mass": 164.93,
+    "radius_bondi": null,
+    "radius_alvarez": 2.81
   },
   "erbium": {
     "name": "erbium",
     "symbol": "Er",
     "atomic number": 68,
-    "mass": 167.26
+    "mass": 167.26,
+    "radius_bondi": null,
+    "radius_alvarez": 2.83
   },
   "thulium": {
     "name": "thulium",
     "symbol": "Tm",
     "atomic number": 69,
-    "mass": 168.93
+    "mass": 168.93,
+    "radius_bondi": null,
+    "radius_alvarez": 2.79
   },
   "ytterbium": {
     "name": "ytterbium",
     "symbol": "Yb",
     "atomic number": 70,
-    "mass": 173.05
+    "mass": 173.05,
+    "radius_bondi": null,
+    "radius_alvarez": 2.80
   },
   "lutetium": {
     "name": "lutetium",
     "symbol": "Lu",
     "atomic number": 71,
-    "mass": 174.97
+    "mass": 174.97,
+    "radius_bondi": null,
+    "radius_alvarez": 2.74
   },
   "hafnium": {
     "name": "hafnium",
     "symbol": "Hf",
     "atomic number": 72,
-    "mass": 178.49
+    "mass": 178.49,
+    "radius_bondi": null,
+    "radius_alvarez": 2.63
   },
   "tantalum": {
     "name": "tantalum",
     "symbol": "Ta",
     "atomic number": 73,
-    "mass": 180.95
+    "mass": 180.95,
+    "radius_bondi": null,
+    "radius_alvarez": 2.53
   },
   "tungsten": {
     "name": "tungsten",
     "symbol": "W",
     "atomic number": 74,
-    "mass": 183.84
+    "mass": 183.84,
+    "radius_bondi": null,
+    "radius_alvarez": 2.57
   },
   "rhenium": {
     "name": "rhenium",
     "symbol": "Re",
     "atomic number": 75,
-    "mass": 186.21
+    "mass": 186.21,
+    "radius_bondi": null,
+    "radius_alvarez": 2.49
   },
   "osmium": {
     "name": "osmium",
     "symbol": "Os",
     "atomic number": 76,
-    "mass": 190.23
+    "mass": 190.23,
+    "radius_bondi": null,
+    "radius_alvarez": 2.48
   },
   "iridium": {
     "name": "iridium",
     "symbol": "Ir",
     "atomic number": 77,
-    "mass": 192.22
+    "mass": 192.22,
+    "radius_bondi": null,
+    "radius_alvarez": 2.41
   },
   "platinum": {
     "name": "platinum",
     "symbol": "Pt",
     "atomic number": 78,
-    "mass": 195.08
+    "mass": 195.08,
+    "radius_bondi": 1.72,
+    "radius_alvarez": 2.29
   },
   "gold": {
     "name": "gold",
     "symbol": "Au",
     "atomic number": 79,
-    "mass": 196.97
+    "mass": 196.97,
+    "radius_bondi": 1.66,
+    "radius_alvarez": 2.32
   },
   "mercury": {
     "name": "mercury",
     "symbol": "Hg",
     "atomic number": 80,
-    "mass": 200.59
+    "mass": 200.59,
+    "radius_bondi": 1.70,
+    "radius_alvarez": 2.45
   },
   "thallium": {
     "name": "thallium",
     "symbol": "Tl",
     "atomic number": 81,
-    "mass": 204.38
+    "mass": 204.38,
+    "radius_bondi": 1.96,
+    "radius_alvarez": 2.47
   },
   "lead": {
     "name": "lead",
     "symbol": "Pb",
     "atomic number": 82,
-    "mass": 207.2
+    "mass": 207.2,
+    "radius_bondi": 2.02,
+    "radius_alvarez": 2.60
   },
   "bismuth": {
     "name": "bismuth",
     "symbol": "Bi",
     "atomic number": 83,
-    "mass": 208.98
+    "mass": 208.98,
+    "radius_bondi": null,
+    "radius_alvarez": 2.54
   },
   "polonium": {
     "name": "polonium",
     "symbol": "Po",
     "atomic number": 84,
-    "mass": 209.0
+    "mass": 209.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "astatine": {
     "name": "astatine",
     "symbol": "At",
     "atomic number": 85,
-    "mass": 210.0
+    "mass": 210.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "radon": {
     "name": "radon",
     "symbol": "Rn",
     "atomic number": 86,
-    "mass": 222.0
+    "mass": 222.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "francium": {
     "name": "francium",
     "symbol": "Fr",
     "atomic number": 87,
-    "mass": 223.0
+    "mass": 223.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "radium": {
     "name": "radium",
     "symbol": "Ra",
     "atomic number": 88,
-    "mass": 226.0
+    "mass": 226.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "actinium": {
     "name": "actinium",
     "symbol": "Ac",
     "atomic number": 89,
-    "mass": 227.0
+    "mass": 227.0,
+    "radius_bondi": null,
+    "radius_alvarez": 2.8
   },
   "thorium": {
     "name": "thorium",
     "symbol": "Th",
     "atomic number": 90,
-    "mass": 232.04
+    "mass": 232.04,
+    "radius_bondi": null,
+    "radius_alvarez": 2.93
   },
   "proactinium": {
     "name": "proactinium",
     "symbol": "Pa",
     "atomic number": 91,
-    "mass": 231.04
+    "mass": 231.04,
+    "radius_bondi": null,
+    "radius_alvarez": 2.88
   },
   "uranium": {
     "name": "uranium",
     "symbol": "U",
     "atomic number": 92,
-    "mass": 238.03
+    "mass": 238.03,
+    "radius_bondi": 1.86,
+    "radius_alvarez": 2.71
   },
   "neptunium": {
     "name": "neptunium",
     "symbol": "Np",
     "atomic number": 93,
-    "mass": 237.0
+    "mass": 237.0,
+    "radius_bondi": null,
+    "radius_alvarez": 2.82
   },
   "plutonium": {
     "name": "plutonium",
     "symbol": "Pu",
     "atomic number": 94,
-    "mass": 244.0
+    "mass": 244.0,
+    "radius_bondi": null,
+    "radius_alvarez": 2.81
   },
   "americium": {
     "name": "americium",
     "symbol": "Am",
     "atomic number": 95,
-    "mass": 243.0
+    "mass": 243.0,
+    "radius_bondi": null,
+    "radius_alvarez": 2.83
   },
   "curium": {
     "name": "curium",
     "symbol": "Cm",
     "atomic number": 96,
-    "mass": 247.0
+    "mass": 247.0,
+    "radius_bondi": null,
+    "radius_alvarez": 3.05
   },
   "berkelium": {
     "name": "berkelium",
     "symbol": "Bk",
     "atomic number": 97,
-    "mass": 247.0
+    "mass": 247.0,
+    "radius_bondi": null,
+    "radius_alvarez": 3.4
   },
   "californium": {
     "name": "californium",
     "symbol": "Cf",
     "atomic number": 98,
-    "mass": 251.0
+    "mass": 251.0,
+    "radius_bondi": null,
+    "radius_alvarez": 3.05
   },
   "einsteinium": {
     "name": "einsteinium",
     "symbol": "Es",
     "atomic number": 99,
-    "mass": 252.0
+    "mass": 252.0,
+    "radius_bondi": null,
+    "radius_alvarez": 2.7
   },
   "fermium": {
     "name": "fermium",
     "symbol": "Fm",
     "atomic number": 100,
-    "mass": 257.0
+    "mass": 257.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "mendelevium": {
     "name": "mendelevium",
     "symbol": "Md",
     "atomic number": 101,
-    "mass": 258.0
+    "mass": 258.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "nobelium": {
     "name": "nobelium",
     "symbol": "No",
     "atomic number": 102,
-    "mass": 259.0
+    "mass": 259.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "lawrencium": {
     "name": "lawrencium",
     "symbol": "Lr",
     "atomic number": 103,
-    "mass": 262.0
+    "mass": 262.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "rutherfordium": {
     "name": "rutherfordium",
     "symbol": "Rf",
     "atomic number": 104,
-    "mass": 267.0
+    "mass": 267.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "dubnium": {
     "name": "dubnium",
     "symbol": "Db",
     "atomic number": 105,
-    "mass": 270.0
+    "mass": 270.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "seaborgium": {
     "name": "seaborgium",
     "symbol": "Sg",
     "atomic number": 106,
-    "mass": 269.0
+    "mass": 269.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "bohrium": {
     "name": "bohrium",
     "symbol": "Bh",
     "atomic number": 107,
-    "mass": 270.0
+    "mass": 270.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "hassium": {
     "name": "hassium",
     "symbol": "Hs",
     "atomic number": 108,
-    "mass": 270.0
+    "mass": 270.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "meitnerium": {
     "name": "meitnerium",
     "symbol": "Mt",
     "atomic number": 109,
-    "mass": 278.0
+    "mass": 278.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "darmstadtium": {
     "name": "darmstadtium",
     "symbol": "Ds",
     "atomic number": 110,
-    "mass": 281.0
+    "mass": 281.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "roentgenium": {
     "name": "roentgenium",
     "symbol": "Rg",
     "atomic number": 111,
-    "mass": 281.0
+    "mass": 281.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "copernicium": {
     "name": "copernicium",
     "symbol": "Cn",
     "atomic number": 112,
-    "mass": 285.0
+    "mass": 285.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "ununtrium": {
     "name": "ununtrium",
     "symbol": "Uut",
     "atomic number": 113,
-    "mass": 286.0
+    "mass": 286.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "flerovium": {
     "name": "flerovium",
     "symbol": "Fl",
     "atomic number": 114,
-    "mass": 289.0
+    "mass": 289.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "ununpentium": {
     "name": "ununpentium",
     "symbol": "Uup",
     "atomic number": 115,
-    "mass": 289.0
+    "mass": 289.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "livermorium": {
     "name": "livermorium",
     "symbol": "Lv",
     "atomic number": 116,
-    "mass": 291.0
+    "mass": 291.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "ununseptium": {
     "name": "ununseptium",
     "symbol": "Uus",
     "atomic number": 117,
-    "mass": 293.0
+    "mass": 293.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   },
   "ununoctium": {
     "name": "ununoctium",
     "symbol": "Uuo",
     "atomic number": 118,
-    "mass": 294.0
+    "mass": 294.0,
+    "radius_bondi": null,
+    "radius_alvarez": null
   }
 }
diff --git a/ele/lib/refs.bib b/ele/lib/refs.bib
index 8f0e92c..f1bc59d 100644
--- a/ele/lib/refs.bib
+++ b/ele/lib/refs.bib
@@ -11,3 +11,37 @@ @article { Atomicweightsoftheelements2013IUPACTechnicalReport
       pages= "265 - 291",
       url = "https://www.degruyter.com/view/journals/pac/88/3/article-p265.xml"
 }
+
+@article{Alvarez:2013:Dalton,
+author ="Alvarez, Santiago",
+title  ="A cartography of the van der Waals territories",
+journal  ="Dalton Trans.",
+year  ="2013",
+volume  ="42",
+issue  ="24",
+pages  ="8617-8636",
+publisher  ="The Royal Society of Chemistry",
+doi  ="10.1039/C3DT50599E",
+url  ="http://dx.doi.org/10.1039/C3DT50599E",
+}
+
+@article{Bondi:1964:JPhysChem,
+  title={van der Waals volumes and radii},
+  author={Bondi, A van},
+  journal={The Journal of physical chemistry},
+  volume={68},
+  number={3},
+  pages={441--451},
+  year={1964},
+  publisher={ACS Publications}
+}
+@article{Bondi:1966:JPhysChem,
+  title={Van der Waals volumes and radii of metals in covalent compounds},
+  author={Bondi, A},
+  journal={The Journal of Physical Chemistry},
+  volume={70},
+  number={9},
+  pages={3006--3007},
+  year={1966},
+  publisher={ACS Publications}
+}
\ No newline at end of file


Test patch:
diff --git a/ele/tests/test_element.py b/ele/tests/test_element.py
index 8ed061b..aa2b2a5 100644
--- a/ele/tests/test_element.py
+++ b/ele/tests/test_element.py
@@ -112,6 +112,13 @@ def test_element_attributes(self):
         assert na.atomic_number == 11
         assert na.name == "sodium"
         assert na.symbol == "Na"
+        assert na.radius_bondi == 2.27
+        assert na.radius_alvarez == 2.50
+
+    def test_missing_attribute(self):
+        uuo = element_from_atomic_number(118)
+        assert uuo.radius_bondi is None
+        assert uuo.radius_alvarez is None
 
     def test_repr(self):
         na = element_from_mass(22.98)