What Is an Atom?

Atoms are the tiny building blocks of all matter. Every object you see, touch, or even breathe is made up of atoms! Each atom contains a nucleus, made of protons and neutrons, surrounded by a cloud of electrons zipping around in different energy levels.

Parts of an Atom

• Protons: Positively charged particles found in the nucleus.
• Neutrons: Neutral particles (no charge), also in the nucleus.
• Electrons: Negatively charged particles, found in shells or orbitals outside the nucleus.

The number of protons defines the element (for example, all hydrogen atoms have 1 proton).

The Periodic Table Connection

The atomic number (Z) is the number of protons in the nucleus. The mass number (A) is the sum of protons and neutrons.

• Isotopes are atoms of the same element with different numbers of neutrons.

Why Does It Matter?

Understanding atomic structure helps us predict how elements will behave in chemical reactions, and even why certain materials conduct electricity or react explosively!

Real-World Impact

• Medicine: Isotopes are used in medical imaging.
• Energy: Nuclear reactors rely on manipulating atomic nuclei.