Electrons are one of the fundamental particles that make up atoms, and they play a critical role in determining the properties of an atom. Electrons are negatively charged subatomic particles that are located outside the nucleus of an atom.Electrons are located in regions surrounding the nucleus of an atom called electron shells. The electrons in an atom are arranged in these shells in a specific way, known as the electron configuration. The first shell, also known as the K-shell, can hold a maximum of 2 electrons. The second shell, or L-shell, can hold a maximum of 8 electrons, and so on. The outermost shell of an atom is known as the valence shell, and the electrons in this shell are known as valence electrons.The number of electrons in the valence shell determines the chemical properties of an atom. Atoms with a full valence shell are less likely to participate in chemical reactions and are considered to be chemically stable. Atoms with less than a full valence shell, on the other hand, are more likely to participate in chemical reactions and are considered to be chemically reactive.The electrons in an atom are also arranged in specific energy levels or orbitals. The electrons in an atom occupy these orbitals in a specific order, known as the Pauli Exclusion Principle. This principle states that no two electrons in an atom can have the same set of quantum numbers.In addition, the electrons in an atom can be in different energy levels, known as energy levels or energy shells. The electrons in the lower energy levels are said to be in a ground state and electrons in higher energy levels are said to be in an excited state.In conclusion, Electrons are negatively charged subatomic particles that are located outside the nucleus of an atom. They are arranged in regions surrounding the nucleus of an atom called electron shells and have a specific electron configuration. The number of electrons in the valence shell determines the chemical properties of an atom, and the electrons are also arranged in specific energy levels or orbitals and have different energy levels known as energy shells. Electrons play a critical role in determining the properties of an atom, and a better understanding of their behavior and location can help us understand the chemical and physical properties of atoms and molecules.