"""
Minimal periodic table for httk-atomistic.
Provides the IUPAC element symbols in atomic-number order and helpers to convert
between a chemical symbol and its atomic number. The pseudo-symbols ``"X"``
(unknown element) and ``"vacancy"`` are deliberately not elements here; they are
handled at the ``Species`` level.
"""
SYMBOLS: tuple[str, ...] = (
"H",
"He",
"Li",
"Be",
"B",
"C",
"N",
"O",
"F",
"Ne",
"Na",
"Mg",
"Al",
"Si",
"P",
"S",
"Cl",
"Ar",
"K",
"Ca",
"Sc",
"Ti",
"V",
"Cr",
"Mn",
"Fe",
"Co",
"Ni",
"Cu",
"Zn",
"Ga",
"Ge",
"As",
"Se",
"Br",
"Kr",
"Rb",
"Sr",
"Y",
"Zr",
"Nb",
"Mo",
"Tc",
"Ru",
"Rh",
"Pd",
"Ag",
"Cd",
"In",
"Sn",
"Sb",
"Te",
"I",
"Xe",
"Cs",
"Ba",
"La",
"Ce",
"Pr",
"Nd",
"Pm",
"Sm",
"Eu",
"Gd",
"Tb",
"Dy",
"Ho",
"Er",
"Tm",
"Yb",
"Lu",
"Hf",
"Ta",
"W",
"Re",
"Os",
"Ir",
"Pt",
"Au",
"Hg",
"Tl",
"Pb",
"Bi",
"Po",
"At",
"Rn",
"Fr",
"Ra",
"Ac",
"Th",
"Pa",
"U",
"Np",
"Pu",
"Am",
"Cm",
"Bk",
"Cf",
"Es",
"Fm",
"Md",
"No",
"Lr",
"Rf",
"Db",
"Sg",
"Bh",
"Hs",
"Mt",
"Ds",
"Rg",
"Cn",
"Nh",
"Fl",
"Mc",
"Lv",
"Ts",
"Og",
)
"""The 118 IUPAC element symbols in atomic-number order (``SYMBOLS[0]`` is hydrogen)."""
_NUMBER_OF: dict[str, int] = {symbol: z for z, symbol in enumerate(SYMBOLS, start=1)}
[docs]
def atomic_number(symbol: str) -> int:
"""Return the atomic number of an element symbol.
The pseudo-symbols ``"X"`` and ``"vacancy"`` are not elements here.
:param symbol: The IUPAC element symbol.
:return: The element's atomic number.
:raises ValueError: If ``symbol`` is not one of the 118 element symbols.
"""
try:
return _NUMBER_OF[symbol]
except KeyError:
raise ValueError(f"Unknown element symbol: {symbol!r}") from None
[docs]
def symbol_of(z: int) -> str:
"""Return the element symbol for an atomic number.
:param z: The atomic number in the range 1 through 118.
:return: The corresponding IUPAC element symbol.
:raises ValueError: If ``z`` is outside the range 1 through 118.
"""
if not 1 <= z <= len(SYMBOLS):
raise ValueError(f"Unknown atomic number: {z!r}")
return SYMBOLS[z - 1]