AP Chemistry: Introduction to the Atom

Atomic Structure Fundamentals

• Atomic Number: Represents the number of protons in the nucleus and equals the number of electrons in a neutral atom.
• Isotopes: Variants of a single element that possess the same atomic number but have different numbers of neutrons, resulting in different masses.

Hydrogen Isotopes

• Protium: The most prevalent isotope of hydrogen, designated as Hydrogen-1.
• Deuterium: Also known as Hydrogen-2, contains one neutron in its nucleus, distinguishing it from Protium.
• Tritium: Known as Hydrogen-3, features two neutrons in its nucleus.

Basic Atomic Concepts

• Elements: Composed of atoms that are all of the same type, defining the chemical properties of the matter.
• Atoms: The fundamental building blocks of elements, incredibly small, with about one million atoms fitting across a hair's width.

Subatomic Particles

• Proton: A positively charged particle located in the nucleus, its number corresponds to the atomic number, with a mass of one atomic mass unit (amu).
• Electron: A negatively charged particle that orbits the nucleus, contributing to an atom's charge balance.
• Neutron: A neutral particle found in the nucleus. Neutrons can vary among isotopes while still identifying as the same element.

Measurement and Constants in Chemistry

• Average Atomic Mass: The weighted average of the atomic masses of an element's naturally occurring isotopes, commonly found in the periodic table beneath the element symbol.
• Atomic Mass Unit (amu): A standard unit for measuring atomic mass, equivalent to approximately 1.660540 x 10^-27 kg.
• Avogadro's Number: A fundamental constant in chemistry representing the quantity 6.02214076 x 10^23, which quantifies the number of particles in one mole.
• Mole: The amount of substance that contains exactly Avogadro's number of specified entities, typically atoms or molecules.