Default: H⁺

Molecules:

• Neutral atoms:1 bond is accepted

• Charged atoms: Not allowed in molecules.

• Radical: Not allowed in molecules.

Ions: H⁺, H^-

Radical:

• H· is accepted

• H without radical and charge or bond is not accepted.

Default: Li, Na, K, Rb, Cs, Fr respectively.

Molecules:

• Neutral atoms:1 bond is accepted.

• Charged atoms: Not allowed in molecules.

• Radical: Not allowed in molecules.

Ions: Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Fr⁺ are accepted.

Radical: Me· is accepted