AP Chemistry: Atomic Structure

Atomic Structure

• Atomic structure consists of protons, neutrons, and electrons
• Protons and neutrons are found in the nucleus, while electrons orbit around it
• Electrons are arranged in energy levels or shells, with each shell having a specific capacity

Effective Nuclear Charge

• Effective nuclear charge (Zeff) is the net positive charge experienced by an electron in an atom
• Zeff is the result of the attractive force between the nucleus and electrons, and the repulsive force between electrons
• Zeff increases from left to right across a period, and decreases down a group

Atomic Radius Trends

• Atomic radius decreases from left to right across a period, and increases down a group
• This is due to the increase in Zeff, which pulls electrons closer to the nucleus
• Atomic radius is measured in picometers (pm)

Ionization Energy

• Ionization energy (IE) is the energy required to remove an electron from an atom
• IE increases from left to right across a period, and decreases down a group
• This is due to the increase in Zeff, which makes it harder to remove an electron

Periodic Table Blocks

• The periodic table is divided into blocks based on the last orbital filled
• The blocks are:
  • s-block (alkali metals and alkaline earth metals)
  • p-block (nonmetals and metalloids)
  • d-block (transition metals)
  • f-block (lanthanides and actinides)

Electronegativity

• Electronegativity is the ability of an atom to attract electrons in a covalent bond
• Electronegativity increases from left to right across a period, and decreases down a group
• Electronegativity is measured using the Pauling scale, with higher values indicating greater electronegativity

Force of Energy

• Not a specific topic in AP Chemistry, but energy is a fundamental concept in chemistry
• Energy is the ability to do work, and is measured in units such as joules (J)

Photoelectron Spectroscopy

• Photoelectron spectroscopy (PES) is a technique used to measure the energy of electrons emitted from an atom
• PES involves bombarding atoms with high-energy radiation, causing electrons to be emitted
• The energy of the emitted electrons is measured, providing information about the atomic orbitals and electron binding energies