Atomic Structure Overview

Study Notes

Atomic Structure Overview

Atoms are the fundamental building blocks of matter, composed of protons, neutrons, and electrons.
Protons and neutrons are located in the nucleus, the atom's positively charged core.
Electrons orbit the nucleus in specific energy levels or shells.
The number of protons in an atom defines its atomic number and identifies the element.
Atoms of the same element with differing neutron counts are called isotopes.
Atomic mass is the sum of protons and neutrons in an atom's nucleus.
Atoms typically strive for a stable electron configuration by gaining, losing, or sharing electrons with other atoms to form chemical bonds.

Subatomic Particles

Protons: Positively charged particles within the nucleus; mass approximately 1 atomic mass unit (amu).
The number of protons defines the element.
Neutrons: Neutrally charged particles within the nucleus; mass approximately 1 amu, slightly greater than a proton's.
The number of neutrons varies among isotopes of the same element.
Electrons: Negatively charged particles orbiting the nucleus in specific energy levels (shells); mass is much less than protons or neutrons.
Electrons dictate an atom's chemical properties.
Electron shells are labeled with principal quantum numbers (e.g., n=1, n=2, n=3...).

Atomic Number and Mass Number

Atomic Number (Z): Number of protons in an atom's nucleus; uniquely identifies each element.
Example: Carbon has an atomic number of 6, meaning 6 protons.
Mass Number (A): Sum of protons and neutrons in an atom's nucleus; approximate atomic mass. Note: approximation due to presence of electrons.
Example: A carbon-12 atom has atomic number 6 and mass number 12 (meaning 6 neutrons).

Isotopes

Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.
They possess identical chemical behavior (react similarly) but exhibit slight variations in physical properties (mass, reactivity).
Example: Carbon isotopes include carbon-12, carbon-13, and carbon-14.

Electronic Structure

Electrons occupy specific energy levels (shells) surrounding the nucleus.
Shells have increasing energy levels.
Each shell can hold a maximum number of electrons (2n^2, where n = shell number).
Electron arrangement critically affects chemical behavior.

Shells and Subshells

The shell model shows electrons orbiting in discrete shells.
Reality also has subshells (s, p, d, f) within each shell where electrons reside.
Each subshell has a specific shape and energy level.
This substructure is essential for understanding chemical bonding.

Description

Explore the fundamental concepts of atomic structure, including the roles of protons, neutrons, and electrons. Understand how atomic number, mass, and isotopes define elements and their behaviors. This quiz will enhance your knowledge of the building blocks of matter.