Atom

An atom is the basic unit of matter, consisting of a nucleus containing protons and neutrons, surrounded by electrons in shells. Atoms are the building blocks of all substances and are incredibly small, with a diameter of about 0.1 to 0.5 nanometers.

Structure of an Atom

The structure of an atom consists of:

1. Nucleus: The central part of an atom, composed of protons and neutrons. Protons carry a positive charge and neutrons carry no charge.
2. Electrons: Negatively charged particles that orbit the nucleus in energy shells or levels.

Subatomic Particles

Atoms are made up of three subatomic particles:

• Protons: Positively charged particles found in the nucleus of an atom.
• Neutrons: Neutral particles found in the nucleus of an atom.
• Electrons: Negatively charged particles that orbit the nucleus in specific energy levels.

Atomic Number and Mass Number

The atomic number of an atom is equal to the number of protons in its nucleus. The mass number is the sum of the number of protons and neutrons in the nucleus.

Study Guide

1. What is an atom?
2. Describe the structure of an atom.
3. What are the three subatomic particles that make up an atom?
4. Explain the concept of atomic number and mass number.

Understanding the structure and components of an atom is fundamental to understanding the behavior and properties of matter. It forms the basis of chemistry and is crucial to various scientific disciplines.

[Atom] Related Worksheets and Study Guides:

• MatterScience • Fourth Grade
• Properties of atomsScience • Eighth Grade
• Atomic Structure - Set IIChemistry • High School