Understanding Atoms

Atoms are the fundamental building blocks of matter, composed of protons, neutrons, and electrons. The arrangement of these subatomic particles determines the properties of each element.

• Protons carry a positive charge and define the atomic number.
• Neutrons are neutral and contribute to atomic mass.
• Electrons orbit the nucleus and are involved in chemical bonding.

The Periodic Table

The periodic table organizes elements by increasing atomic number and groups them based on similar chemical properties. The table reveals periodic trends, such as atomic radius, ionization energy, and electronegativity.

• Groups are columns with similar valence electron configurations.
• Periods are rows indicating energy levels.

Periodic Trends

• Atomic Radius: Decreases across a period, increases down a group.
• Ionization Energy: Increases across a period, decreases down a group.
• Electronegativity: Tendency to attract electrons; increases across a period.

Why It Matters

Understanding atomic structure and periodicity is key to predicting how elements interact, their reactivity, and their role in compounds.

Real-World Relevance

• Explains why sodium (Na) reacts explosively with water, while neon (Ne) is inert.
• Essential for understanding how materials like semiconductors are designed.