Introduction to Atoms, Elements, and Molecules

Periodic Table Overview

• The Periodic Table is a systematic arrangement of all known chemical elements, organized by atomic number, electron configuration, and recurring chemical properties.

• Focus on five fundamental elements: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), and Phosphorus (P), which are essential for all known forms of life. Each of these elements plays a critical role in biological processes, such as energy transfer and the building of molecules.

• The table is not static; new elements are discovered or synthesized, and the organization reflects our evolving understanding of atomic structure and chemistry.

Atoms, Elements, and Molecules

• Atom: The smallest stable unit of matter, containing a nucleus made of protons (positively charged) and neutrons (neutral), surrounded by a cloud of electrons (negatively charged). Atoms are the basic building blocks of matter and determine the chemical properties of elements.

• Element: A pure substance consisting of only one type of atom, defined by its atomic number, which indicates the number of protons in its nucleus. Elements cannot be broken down into simpler substances by chemical means. Each element has unique properties and is represented by a one- or two-letter symbol.

• Molecule: A group of two or more atoms bonded together through chemical bonds. Molecules can consist of the same or different elements and can vary in complexity; for example, oxygen (O₂) is a diatomic molecule while glucose (C₆H₁₂O₆) is a larger, more complex molecule.

Chemical Bonds

• Types of Bonds: The main types of chemical bonds are Ionic, Covalent, and Metallic, each with distinct characteristics and behaviors.

• Ionic Bonds: Formed through the transfer of electrons from one atom to another, leading to the creation of charged ions. Example: Sodium (Na) transfers an electron to Chlorine (Cl), resulting in a stable ionic compound NaCl (table salt).

• Covalent Bonds: Involve the sharing of electron pairs between atoms, which helps to achieve stability. Example: In water (H₂O), each hydrogen atom shares electrons with one oxygen atom, resulting in a bent molecular shape which is crucial for its unique properties.

• Metallic Bonds: Occur between metal atoms where electrons are shared in a ‘sea’ of electrons, allowing for electrical conductivity and malleability.

• Understanding chemical bonds is essential for grasping how substances interact in chemical reactions and the formation of new compounds, influencing properties such as boiling points, solubility, and reactivity.

Notes on Learning Materials

• The learning materials include various visual aids such as images and diagrams that illustrate concepts like atomic structure and the arrangement of the periodic table. These visuals are intended to enhance comprehension and retention of complex topics.

• Non-examinable slides are marked with the ME icon, indicating content that is supplementary and not required for assessments, allowing students to focus on crucial information while fostering broader understanding.