In an atom, electrons ____.

a. are located in the nucleus
b. travel outside the nucleus
c. are paired with neutrons
d. are always in the same place in an atom

I suspect your teacher wants you to regurgitate answer b. Truth is, it is much more complicated than that, and when you get to quantum physics in college, you will realize that. Look up on google schrodinger's cat http://www.telegraph.co.uk/technology/google/google-doodle/10237347/Schrodingers-Cat-explained.html

The same principle applies to looking to see where the electron is.

In an atom, electrons (b) travel outside the nucleus.

To understand this, let's explore the structure of an atom. Atoms are composed of three main subatomic particles: protons, neutrons, and electrons. Protons and neutrons are located in the nucleus at the center of the atom, while electrons orbit around the nucleus in specific energy levels or shells.

The electrons are negatively charged particles that are much smaller and lighter than protons and neutrons. They have a negligible mass compared to the other subatomic particles. Electrons are distributed in different energy levels, also known as electron shells or orbitals, which are located at various distances from the nucleus.

The arrangement of electrons in an atom is often depicted using electron configuration, which is based on principles such as the Aufbau principle, Pauli exclusion principle, and Hund's rule. According to the electron configuration, electrons occupy the available energy levels starting from the one closest to the nucleus, filling up each level before moving to the next.

The outermost energy level of an atom is called the valence shell. Electrons in the valence shell are responsible for the atom's chemical properties, as they participate in bonding with other atoms. These valence electrons are the ones that "travel outside the nucleus" and are involved in forming chemical bonds or being transferred between atoms during chemical reactions.

Hence, the correct option is (b) – electrons travel outside the nucleus.