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3. Atoms and Molecules

Learn about 3. Atoms and Molecules and discover its key concepts through interactive lessons and practical exercises.

Sections

ATOMS AND MOLECULES

The section discusses the foundational concepts of atoms and molecules, including the laws of conservation of mass and constant proportions, and introduces Dalton's atomic theory.

3 Section Overview

Start current section content and materials

3.1 Laws of Chemical Combination

The section discusses the fundamental laws governing chemical combinations, namely the Law of Conservation of Mass and the Law of Constant Proportions.

3.1.1 LAW OF CONSERVATION OF MASS

The Law of Conservation of Mass states that mass is neither created nor destroyed in a chemical reaction.

3.1.2 LAW OF CONSTANT PROPORTIONS

The Law of Constant Proportions states that in a chemical compound, elements combine in fixed ratios by mass.

3.2 What is an Atom?

This section introduces the concept of atoms as the fundamental building blocks of matter, detailing their properties, symbols, and significance in chemical reactions.

3.2.1 WHAT ARE THE MODERN DAY SYMBOLS OF ATOMS OF DIFFERENT ELEMENTS

This section discusses the historical development and modern representation of atomic symbols for different elements.

3.2.2 ATOMIC MASS

This section discusses the concept of atomic mass and highlights its significance in atomic theory.

3.2.3 HOW DO ATOMS EXIST

Atoms of most elements cannot exist independently; they form molecules or ions that aggregate to create matter.

3.3 What is a Molecule?

A molecule is defined as a group of two or more atoms that are chemically bonded together, representing the smallest particle of an element or compound capable of independent existence.

3.3.1 MOLECULES OF ELEMENTS

This section explains the concept of molecules, particularly focusing on how elements are composed of molecules formed from the same type of atoms.

3.3.2 MOLECULES OF COMPOUNDS

Compounds are formed when atoms of different elements combine in fixed proportions, resulting in unique chemical structures and properties.

3.3.3 WHAT IS AN ION?

This section discusses the concept of ions in compounds formed from metals and non-metals, expounding on the terms anions, cations, and polyatomic ions.

3.4 Writing Chemical Formulae

This section introduces the rules for writing chemical formulae of compounds based on the valencies and combinations of elements.

3.4.1 FORMULAE OF SIMPLE COMPOUNDS

This section explains the concept of binary compounds, their valency, and how to write chemical formulae for simple compounds.

3.5 Molecular Mass

Molecular Mass refers to the sum of the atomic masses of all atoms in a molecule, expressed in atomic mass units (u).

3.5.1 MOLECULAR MASS

This section introduces the concept of molecular mass, explaining how it can be calculated by summing the atomic masses of the atoms present in a molecule.

3.5.2 FORMULA UNIT MASS

This section introduces the concept of formula unit mass, explaining how to calculate it and its relationship with molecular mass.

Learning Objectives

  • Master the fundamentals of 3. Atoms and Molecules

  • Apply learned concepts in practical scenarios

  • Successfully complete all chapter exercises