Valence electrons are the outermost electrons of an atom, located in the highest energy level or valence shell. They are responsible for determining the chemical properties of an element and are involved in chemical reactions and bonding.The number of valence electrons an atom has is determined by the element's position on the periodic table. The elements in the first two rows of the periodic table, the s-block and p-block, have valence electrons in their outermost energy level. The s-block elements have valence electrons in the s-orbital, which can hold a maximum of 2 electrons, while the p-block elements have valence electrons in the p-orbital, which can hold a maximum of 6 electrons.Valence electrons play a crucial role in chemical reactions and bonding. They are involved in the formation of chemical bonds, which occur when atoms share or transfer valence electrons to achieve a stable electron configuration. When two or more atoms share valence electrons, it is called a covalent bond. When one atom loses or gains valence electrons, it is called an ionic bond.Valence electrons also play a key role in determining the reactivity of an element. Elements with a full valence shell, also known as a noble gas configuration, are generally less reactive because they have a stable electron configuration. On the other hand, elements with an incomplete valence shell are more reactive, as they are seeking to achieve a stable electron configuration.In conclusion, valence electrons are the outermost electrons of an atom, located in the highest energy level or valence shell. They determine the chemical properties of an element and are involved in chemical reactions and bonding. The number of valence electrons an atom has is determined by the element's position on the periodic table. Valence electrons play a crucial role in chemical reactions and bonding, they also determine the reactivity of an element. They are responsible for the formation of chemical bonds, which occur when atoms share or transfer valence electrons to achieve a stable electron configuration.