Final answer:
The molecule formed between an atom of astatine and an atom of hydrogen is held together by a covalent bond and should be named hydrogen astatide according to IUPAC nomenclature.
Step-by-step explanation:
The molecule formed between an atom of astatine and an atom of hydrogen would have a covalent bond. Astatine is a halogen, and like other halogens, it tends to form single covalent bonds with hydrogen. The IUPAC name of this molecule would be hydrogen astatide. This is because, according to IUPAC nomenclature for binary compounds (compounds consisting of two different elements), the hydrogen is named first followed by the halogen with its ending changed to -ide. Therefore, combining hydrogen and astatine, we get hydrogen astatide.
A single covalent bond is created when the hydrogen atom shares its sole electron with one of the valence electrons of astatine, enabling both to achieve a more stable electronic configuration. Covalent bonding often occurs between nonmetals, as they have comparable tendencies to attract electrons to themselves. This shared pair of electrons constitutes the covalent bond that holds the two atoms together. Such bonds are a balance between the attractions of electrons to the nuclei and the repulsions between like-charges within the molecule.