What is the only element in group 1 on the periodic table that forms covalent bonds?

Hydrogen.

Explanation:

The position of hydrogen was always controversial. It resembles both alkali metals and halogens.

However, it is placed with alkali metals in the periodic table in group 1.

The other elements are all metals and are able to give electrons easily so they form ionic bonds only.

While hydrogen can from covalent bond as it can share electrons.

Example : water.

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.