Data

To find out how to fetch data in bulk, check out the documentation about data access.

Elements

The following data are currently available:

Name

Type

Comment

Unit

Data Source

abundance_crust

float

Abundance in the Earth’s crust

mg/kg

[23]

abundance_sea

float

Abundance in the seas

mg/L

[23]

annotation

str

Annotations regarding the data

atomic_number

int

Atomic number

atomic_radius

float

Atomic radius

pm

[53]

atomic_radius_rahm

float

Atomic radius by Rahm et al.

pm

[45, 46]

atomic_volume

float

Atomic volume

cm3/mol

atomic_weight

float

Atomic weight(1)

[35, 63]

atomic_weight_uncertainty

float

Atomic weight uncertainty(1)

[35, 63]

block

str

Block in periodic table

boiling_point

float

Boiling temperature

K

[22]

c6

float

C_6 dispersion coefficient in a.u.

a.u.

[13, 56]

c6_gb

float

C_6 dispersion coefficient in a.u. (Gould & Bučko)

a.u.

[21]

cas

str

Chemical Abstracts Serice identifier

covalent_radius_bragg

float

Covalent radius by Bragg

pm

[10]

covalent_radius_cordero

float

Covalent radius by Cerdero et al.(2)

pm

[16]

covalent_radius_pyykko

float

Single bond covalent radius by Pyykko et al.

pm

[43]

covalent_radius_pyykko_double

float

Double bond covalent radius by Pyykko et al.

pm

[42]

covalent_radius_pyykko_triple

float

Triple bond covalent radius by Pyykko et al.

pm

[44]

cpk_color

str

Element color in CPK convention

HEX

[61]

critical_pressure

float

Critical pressure

MPa

[22]

critical_temperature

float

Critical temperature

K

[22]

density

float

Density at 295K(9)

g/cm3

[23, 66]

description

str

Short description of the element

dipole_polarizability

float

Dipole polarizability

a.u.

[51]

dipole_polarizability_unc

float

Dipole polarizability uncertainty

a.u.

[51]

discoverers

str

The discoverers of the element

discovery_location

str

The location where the element was discovered

discovery_year

int

The year the element was discovered

electron_affinity

float

Electron affinity(3)

eV

[6, 23]

electrons

int

Number of electrons

electrophilicity

float

Electrophilicity index

eV

[39]

en_allen

float

Allen’s scale of electronegativity(4)

eV

[31, 32]

en_ghosh

float

Ghosh’s scale of electronegativity

[18]

en_mulliken

float

Mulliken’s scale of electronegativity

eV

[36]

en_pauling

float

Pauling’s scale of electronegativity

[23]

econf

str

Ground state electron configuration

evaporation_heat

float

Evaporation heat

kJ/mol

fusion_heat

float

Fusion heat

kJ/mol

gas_basicity

float

Gas basicity

kJ/mol

[23]

geochemical_class

str

Geochemical classification

[59]

glawe_number

int

Glawe’s number (scale)

[19]

goldschmidt_class

str

Goldschmidt classification

[59, 60]

group

int

Group in periodic table

heat_of_formation

float

Heat of formation

kJ/mol

[23]

inchi

str

International Chemical Identifier

[24]

ionenergy

tuple

Ionization energies

eV

[26]

ionic_radii

list

Ionic and crystal radii in pm(8)

pm

[29, 52]

is_monoisotopic

bool

Is the element monoisotopic

is_radioactive

bool

Is the element radioactive

isotopes

list

Isotopes

jmol_color

str

Element color in Jmol convention

HEX

[64]

lattice_constant

float

Lattice constant

Angstrom

lattice_structure

str

Lattice structure code

mass_number

int

Mass number (most abundant isotope)

melting_point

float

Melting temperature

K

[22]

mendeleev_number

int

Mendeleev’s number(5)

[41, 57]

metallic_radius

float

Single-bond metallic radius

pm

[1]

metallic_radius_c12

float

Metallic radius with 12 nearest neighbors

pm

[1]

molar_heat_capacity

float

Molar heat capacity @ 25 C, 1 bar

J/(mol K)

[23]

molcas_gv_color

str

Element color in MOCAS GV convention

HEX

[65]

name

str

Name in English

name_origin

str

Origin of the name

neutrons

int

Number of neutrons (most abundant isotope)

oxistates

list

Commonly occurring oxidation states

[67]

nist_webbook_url

str

URL for the NIST Chemistry WebBook

[38]

oxistates

list

Oxidation states

period

int

Period in periodic table

pettifor_number

float

Pettifor scale

[41]

proton_affinity

float

Proton affinity

kJ/mol

[23]

protons

int

Number of protons

sconst

float

Nuclear charge screening constants(6)

[14, 15]

series

int

Index to chemical series

sources

str

Sources of the element

specific_heat_capacity

float

Specific heat capacity @ 25 C, 1 bar

J/(g K)

[23]

symbol

str

Chemical symbol

thermal_conductivity

float

Thermal conductivity @25 C

W/(m K)

triple_point_pressure

float

Triple point pressure

kPa

[22]

triple_point_temperature

float

Triple point temperature

K

[22]

uses

str

Applications of the element

vdw_radius

float

Van der Waals radius

pm

[23]

vdw_radius_alvarez

float

Van der Waals radius according to Alvarez(7)

pm

[5, 58]

vdw_radius_batsanov

float

Van der Waals radius according to Batsanov

pm

[8]

vdw_radius_bondi

float

Van der Waals radius according to Bondi

pm

[9]

vdw_radius_dreiding

float

Van der Waals radius from the DREIDING FF

pm

[34]

vdw_radius_mm3

float

Van der Waals radius from the MM3 FF

pm

[3]

vdw_radius_rt

float

Van der Waals radius according to Rowland and Taylor

pm

[48]

vdw_radius_truhlar

float

Van der Waals radius according to Truhlar

pm

[33]

vdw_radius_uff

float

Van der Waals radius from the UFF

pm

[47]

Isotopes

Name

Type

Comment

Unit

Data Source

abundance

float

Relative Abundance

[25]

abundance_uncertainty

float

Uncertainty of relative abundance

[25]

atomic_number

int

Atomic number

decay_modes

obj

Decay modes with intensities

[25]

discovery_year

int

Year the isotope was discovered

[25]

g_factor

float

Nuclear g-factor

[55]

g_factor_uncertainty

float

Uncertainty of the nuclear g-factor

[55]

half_life

float

Half life of the isotope

[25]

half_life_uncertainty

float

Uncertainty of the half life

[25]

half_life_unit

str

Unit in which the half life is given

[25]

is_radioactive

bool

Is the isotope radioactive

[62]

mass

float

Atomic mass

Da

[62]

mass_number

int

Mass number of the isotope

[62]

mass_uncertainty

float

Uncertainty of the atomic mass

Da

[62]

parity

str

Parity, if present, it can be either + or -

[25]

quadrupole_moment

float

Nuclear electric quadrupole moment

b [100 fm2]

[54]

quadrupole_moment_uncertainty

float

Nuclear electric quadrupole moment

b [100 fm2]

[54]

spin

str

Nuclear spin quantum number

[25]

Isotope Decay Modes

Name

Type

Comment

Unit

Data Source

isotope_id

int

ID of the isotope

mode

str

ASCII symbol of the decay mode

[25]

relation

str

Uncertainty of relative abundance

[25]

intensity

float

Intensity of the decay mode

%

[25]

is_allowed_not_observed

bool

If True decay mode is energetically allowed, but not experimentally observed

[25]

is_observed_intensity_unknown

bool

If True decay mode is observed, but its intensity is not experimentally known

[25]

The different modes in the table are stores as ASCII representations for compatibility. The table below provides explanations of the symbols.

ASCII

Unicode

Description

A

\(\alpha\)

\(\alpha\) emission

p

p

proton emission

2p

2p

2-proton emission

n

n

neutron emission

2n

2n

2-neutron emission

EC

\(\epsilon\)

electron capture

e+

\(e^{+}\)

positron emission

B+

\(\beta^{+}\)

\(\beta^{+}\) decay (\(\beta^{+}=\epsilon+e^{+}\))

B-

\(\beta^{-}\)

\(\beta^{-}\) decay

2B-

2\(\beta^{-}\)

double \(\beta^{-}\) decay

2B+

2\(\beta^{+}\)

double \(\beta^{+}\) decay

B-n

\(\beta^{-}\) n

\(\beta^{-}\)-delayed neutron emission

B-2n

\(\beta^{-}\) 2n

\(\beta^{-}\)-delayed 2-neutron emission

B-3n

\(\beta^{-}\) 3n

\(\beta^{-}\)-delayed 3-neutron emission

B+p

\(\beta^{+}\) p

\(\beta^{+}\)-delayed proton emission

B+2p

\(\beta^{+}\) 2p

\(\beta^{+}\)-delayed 2-proton emission

B+3p

\(\beta^{+}\) 3p

\(\beta^{+}\)-delayed 3-proton emission

B-A

\(\beta^{-}\alpha\)

\(\beta^{-}\)-delayed \(\alpha\) emission

B+A

\(\beta^{+}\alpha\)

\(\beta^{+}\)-delayed \(\alpha\) emission

B-d

\(\beta^{-}\) d

\(\beta^{-}\)-delayed deuteron emission

B-t

\(\beta^{-}\) t

\(\beta^{-}\)-delayed triton emission

IT

IT

internal transition

SF

SF

spontaneous fission

B+SF

\(\beta^{+}\) SF

\(\beta^{+}\)-delayed fission

B-SF

\(\beta^{-}\) SF

\(\beta^{-}\)-delayed fission

24Ne

24Ne

heavy cluster emission

Data Footnotes

1(1,2)

Atomic Weights

Atomic weights and their uncertainties were retrieved mainly from ref. [63]. For elements whose values were given as ranges the conventional atomic weights from Table 3 in ref. [35] were taken. For radioactive elements the standard approach was adopted where the weight is taken as the mass number of the most stable isotope. The data was obtained from CIAAW page on radioactive elements. In cases where two isotopes were specified the one with the smaller standard deviation was chosen. In case of Tc and Pm relative weights of their isotopes were used, for Tc isotope 98, and for Pm isotope 145 were taken from CIAAW.

2

Covalent Radius by Cordero et al.

In order to have a more homogeneous data for covalent radii taken from ref. [16] the values for 3 different valences for C, also the low and high spin values for Mn, Fe Co, were respectively averaged.

3

Electron affinity

Electron affinities were taken from [23] for the elements for which the data was available. For He, Be, N, Ar and Xe affinities were taken from [6] where they were specified for metastable ions and therefore the values are negative.

Updates

  • Electron affinity of niobium was taken from [30].

  • Electron affinity of cobalt was taken from [11].

  • Electron affinity of lead was taken from [12].

4

Allen’s configuration energies

The values of configurational energies from refs. [31] and [32] were taken as reported in eV without converting to Pauling units.

5

Mendeleev numbers

Mendeleev numbers were mostly taken from [57] but the range was extended to cover the whole periodic table following the prescription in the article of increasing the numbers going from top to bottom in each group and group by group from left to right in the periodic table.

6

Nuclear charge screening constants

The screening constants were calculated according to the following formula

\[\sigma_{n,l,m} = Z - n\cdot\zeta_{n,l,m}\]

where \(n\) is the principal quantum number, \(Z\) is the atomic number, \(\sigma_{n,l,m}\) is the screening constant, \(\zeta_{n,l,m}\) is the optimized exponent from [14, 15].

For elements Nb, Mo, Ru, Rh, Pd and Ag the exponent values corresponding to the ground state electronic configuration were taken (entries with superscript a in Table II in [15]).

For elements La, Pr, Nd and Pm two exponent were reported for 4f shell denoted 4f and 4f’ in [15]. The value corresponding to 4f were used since according to the authors these are the dominant ones.

7

van der Waals radii according to Alvarez

The bulk of the radii data was taken from Ref. [5], but the radii for noble gasses were update according to the values in Ref. [58].

8

Ionic radii for Actinoid (III) ions

Ionic radii values for 3+ Actinoids were with coordination number 9 were taken from [29]. In addition crystal_radius values were computed by adding 14 pm to the ionic_radius values according to [52].

9

Densities

Density values for solids and liquids are always in units of grams per cubic centimeter and can be assumed to refer to temperatures near room temperature unless otherwise stated. Values for gases are the calculated ideal gas densities at 25°C and 101.325 kPa.

Original values for gasses are converted from g/L to g/cm3.

For elements where several allotropes exist, the density corresponding to the most abundand are reported (for full list refer to [23]), namely:

  • Antimony (gray)

  • Berkelium (α form)

  • Carbon (graphite)

  • Phosphorus (white)

  • Selenium (gray)

  • Sulfur (rhombic)

  • Tin (white)

For elements where experimental data is not available, theoretical estimates taken from [66] are used, namely for:

  • Astatine

  • Francium

  • Einsteinium

  • Fermium

  • Mendelevium

  • Nobelium

  • Lawrencium

  • Rutherfordium

  • Dubnium

  • Seaborgium

  • Bohrium

  • Hassium

  • Meitnerium

  • Darmstadtium

  • Roentgenium

  • Copernicium

  • Nihonium

  • Flerovium

  • Moscovium

  • Livermorium

  • Tennessine

  • Oganesson