Atomic Structure Basics

Atomic Structure

Subatomic Particles

• Protons: positively charged, reside in the nucleus, determine atomic number (identity of element)
• Neutrons: no charge, reside in the nucleus, contribute to atomic mass
• Electrons: negatively charged, orbit the nucleus, determine chemical properties

Atomic Nucleus

• Nucleus: central region of the atom containing protons and neutrons
• Atomic number (Z): number of protons in the nucleus, unique to each element
• Atomic mass (A): total number of protons and neutrons in the nucleus

Electron Configuration

• Electron shells: energy levels around the nucleus where electrons orbit
• Valence shell: outermost energy level, determines chemical reactivity
• Electron spin: intrinsic property of electrons, can be +1/2 or -1/2

Electron Orbitals

• S orbitals: spherical shape, can hold up to 2 electrons
• P orbitals: dumbbell shape, can hold up to 6 electrons
• D orbitals: complex shape, can hold up to 10 electrons
• F orbitals: complex shape, can hold up to 14 electrons

Energy Levels

• Ground state: lowest energy state of an atom
• Excited state: higher energy state of an atom, electrons jump to higher orbitals
• Ionization energy: energy required to remove an electron from the atom
• Electron affinity: energy released when an electron is added to the atom

Atomic Structure

Subatomic Particles

• Protons have a positive charge and reside in the nucleus, determining the atomic number which identifies an element.
• Neutrons have no charge, reside in the nucleus, and contribute to the atomic mass.
• Electrons have a negative charge, orbit the nucleus, and determine the chemical properties of an element.

Atomic Nucleus

• The nucleus is the central region of the atom containing protons and neutrons, which make up the atom's core.
• Atomic number (Z) is the number of protons in the nucleus, unique to each element.
• Atomic mass (A) is the total number of protons and neutrons in the nucleus, which determines the mass of an atom.

Electron Configuration

• Electron shells are energy levels around the nucleus where electrons orbit, with each shell having a specific energy level.
• The valence shell is the outermost energy level, which determines an element's chemical reactivity.
• Electron spin is an intrinsic property of electrons, which can be either +1/2 or -1/2.

Electron Orbitals

• S orbitals are spherical in shape and can hold up to 2 electrons.
• P orbitals are dumbbell-shaped and can hold up to 6 electrons.
• D orbitals are complex in shape and can hold up to 10 electrons.
• F orbitals are complex in shape and can hold up to 14 electrons.

Energy Levels

• The ground state is the lowest energy state of an atom, where electrons are in their lowest energy orbitals.
• Excited states are higher energy states of an atom, where electrons jump to higher orbitals, releasing energy.
• Ionization energy is the energy required to remove an electron from an atom, resulting in a positive ion.
• Electron affinity is the energy released when an electron is added to an atom, resulting in a negative ion.

Learn about the subatomic particles, atomic nucleus, and atomic number in this quiz on atomic structure. Understand the roles of protons, neutrons, and electrons in an atom.