How many valence electrons does selenium have?

six electrons

Explanation:

The six electrons in the outermost shell allow selenium to have a variety of valence numbers. Selenium compounds have been found that have valences of -2, 4, and 6. Speaking of the number six, selenium is found to have six naturally occurring isotopes.

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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.