Which particles are located in the nucleus of an atom? Choose 2 answers.

The modern atomic model describes an atom as consisting of a small, dense, positively charged nucleus surrounded by a cloud of negatively charged electrons. The nucleus itself is composed of two types of subatomic particles: protons, which carry a positive electric charge, and neutrons, which have no electric charge. These two particles, collectively known as nucleons, are bound together by the strong nuclear force and contain nearly all of the atom's mass.

B. Electrons: Electrons are fundamental particles that orbit the atomic nucleus in specific energy levels or shells; they are not located within the nucleus.

D. Positrons: A positron is the antimatter counterpart of an electron. It is not a constituent particle of a stable atom's nucleus.

1. OpenStax, Chemistry 2e. (2019). Rice University. In Section 2.3, "Atomic Structure and Symbolism," it is stated, "An atom is composed of a small, positively charged nucleus surrounded by electrons. The nucleus contains most of the atom’s mass and is composed of protons and neutrons." (Available at openstax.org)

2. MIT OpenCourseWare, 3.091SC Introduction to Solid State Chemistry, Fall 2010. Lecture 2: The Periodic Table. The lecture notes explicitly describe the Rutherford model of the atom, identifying the nucleus as the central core containing protons and neutrons, with electrons orbiting it. (See Lecture 2 Notes, pp. 2-3).

3. Krane, K. S. (2012). Introductory Nuclear Physics. John Wiley & Sons. In Chapter 1, "Basic Concepts," Section 1.1, it is defined that "The nucleus is composed of protons and neutrons... The proton and neutron are the two members of a family of particles called nucleons." (p. 4).