The simplest way of accessing the elements is importing them directly from mendeleev by symbols
from mendeleev import Si, Fe, O
print("Si's name: ", Si.name)
print("Fe's atomic number:", Fe.atomic_number)
print("O's atomic weight: ", O.atomic_weight)
An alternative interface to the data is through the element function that returns a single Element object or a list of Element object depending on the arguments.
The function can be imported directly from the mendeleev package
from mendeleev import element
The element method accepts unique identifiers: atomic number, atomic symbol or element’s name in English. To retrieve the entries on Silicon by symbol type
si = element('Si')
si
Similarly to access the data by atomic number or element names type
al = element(13)
print(al.name)
o = element('Oxygen')
print(o.atomic_number)
The element method also accepts list or tuple of identifiers and then returns a list of Element objects
c, h, o = element(['C', 'Hydrogen', 8])
print(c.name, h.name, o.name)
Next to simple attributes returning str, int or float, there are extended attributes
oxistates, returns a list of oxidation statesionenergies, returns a dictionary of ionization energiesisotopes, returns a list of Isotope objectsionic_radii returns a list of IonicRadius objectsec, electronic configuration objectoxistates returns a list of most common oxidation states for a given element
fe = element('Fe')
print(fe.oxistates)
The ionenergies returns a dictionary with ionization energies in eV as values and degrees of ionization as keys
o = element('O')
o.ionenergies
The isotopes attribute returns a list of Isotope objects with the following attributes per isotope
print("{0:^4s} {1:^4s} {2:^10s} {3:8s} {4:6s} {5:5s}\n{6}".format("AN", "MN", "Mass", "Unc.", "Abu.", "Rad.", "-" * 42))
for iso in fe.isotopes:
print('{0:4d} {1:4d} {2:10.5f} {3:8.2e} {4:} {5:}'.format(
iso.atomic_number, iso.mass_number, iso.mass, iso.mass_uncertainty, iso.abundance, iso.is_radioactive))
Similarly to element function that can be used to fetch specific isotopes by:
atomic_number and mass_number orsymbol and mass_numberfrom mendeleev import isotope
isotope("Fe", mass_number=57)
# tritium
isotope(1, 3)
Radioactive isotopes can have multiple decay modes and that data is available as decay_modes attrobute for each Isotope
isotope("Li", 11).decay_modes
Another composite attribute is ionic_radii which returns a list of IonicRadius object with the following attributes
atomic_number, atomic number of the ioncharge, charge of the ioneconf, electronic configuration of the ioncoordination, coordination type of the ionspin, spin state of the ion (HS or LS)crystal_radius, crystal radius in pmionic_radius, ionic radius in pmorigin, source of the datamost_reliable, recommended value, (see the original paper for more information)for ir in fe.ionic_radii:
print(ir)
Next to stored attributes there is a number of useful functions
si = element('Si')
# get the number of valence electrons
si.nvalence()
# calculate softness for an ion
si.softness(charge=2)
# calcualte hardness for an ion
si.hardness(charge=4)
# calculate the effective nuclear charge for a subshell using Slater's rules
si.zeff(n=3, o='s')
# calculate the effective nuclear charge for a subshell using Clemneti's and Raimondi's exponents
si.zeff(n=3, o='s', method='clementi')
Currently there are 9 electronagativity scales implemented that can me accessed though the common electronegativity method, the scales are:
allenallred-rochowcottrell-suttonghoshgordyli-xuemartynov-batsanovmullikennaglepaulingsandersonMore information can be found in the documentation.
si.electronegativity(scale='pauling')
si.electronegativity(scale='allen')
# calculate mulliken electronegativity for a neutral atom or ion
si.electronegativity(scale="mulliken", charge=1)
For those who work in the terminal there is a simple command line interface (CLI) for printing the information about a given element. The script name is element.py and it accepts either the symbol or name of the element as an argument and prints the data about it. For example, to print the properties of silicon type
!element.py Si