Introduction of Elements, Compounds, and Mixtures | Chemistry for EmSAT Achieve PDF Download

Introduction

• All the matter in our knowledge can be broken down into pure substances and mixtures. Pure substances can be further broken down into elements and compounds. Elements and compounds have a constant chemical composition, and thus they have uniform chemical properties.
• Pure water extracted from a plant and obtained by purifying tap water will be made up of a combination of hydrogen and oxygen that is constant irrespective of the source. But mixtures are not so. They are substances formed by physically mixing other substances. The components of a mixture do not form chemical bonds like they do in a compound. It is essential to introduce elements, compounds, and mixtures since these form the basis of studying matter and its properties.

Elements

In chemistry, an element is a pure substance made up of only one type of atom. All the atoms of an element will have the same number of protons in their nucleus. This number of protons represents the atomic number of the element. Elements are placed in the periodic table according to their atomic number.

Elements can be categorized into metals, non-metals, and metalloids in the periodic table.

Metals

Metallic elements are usually found on the left side of the periodic table. These elements share some common characteristics:

• Can act as conductors of electricity.
• Are typically ductile (can be drawn into wires).
• Are malleable (can be beaten into sheets).
• Have a shiny surface.
• Can sometimes be magnetic.
• Are usually electropositive.

Examples: Iron (Fe), Aluminium (Al), Copper (Cu), Mercury (Hg), and Lead (Pb).

Non-Metals

These elements are placed on the right side of the periodic table. They share specific properties that categorize them as non-metals:

• Do not have a shiny appearance.
• Usually do not conduct electricity.
• Are not malleable.
• Are not ductile.
• Are generally electronegative.
• Are not magnetic.

Examples: Fluorine (F), Chlorine (Cl), Iodine (I), etc.

Metalloids

These are elements that have properties that are a mixture of both metals and non-metals. There is no universally recognized definition of metalloids. However, the most agreed-upon metalloids are:

• Boron
• Silicon
• Germanium
• Arsenic
• Antimony
• Tellurium

Compounds

A chemical compound results from two or more elements combining through a chemical process. When elements combine through chemical processes, bonds are formed between their atoms by sharing or transferring electrons. This process is known as chemical bonding. Most elements on Earth combine to form compounds. These compounds play an essential part in the life of our planet, as they form the building blocks of all organic matter and salts necessary for the survival of organisms.

Chemical compounds are made up of atoms that combine in a fixed ratio, and the molecules thus formed occupy a defined space. These atoms are held together by chemical bonds, based on which compounds can be classified as:

• Molecular compounds: Compounds with covalent bonds.
• Salts: Compounds with ionic bonding.
• Intermetallic compounds: Compounds with metallic bonding.
• Complexes: Compounds with coordinate covalent bonds.

Mixtures

When two or more substances are mixed but are not combined by a chemical process, the result is a mixture. This means that the components retain their natural and chemical properties. In compounds, the electrons realign to form a substance with its own properties, often different from the parent components.

Examples of mixtures: Alloys, suspensions, colloids, and solutions.

Types of Mixtures
Heterogeneous mixtures:

• In these mixtures, the substances combined can be easily seen and separated.
• Examples: Conglomerate rock, sand and iron filing powder, sand and water, a salad, etc.

Homogeneous mixtures:

• In these mixtures, the components cannot be distinguished and require special procedures to separate them.
• Examples: Mayonnaise, air, saline solution, most alloys, etc.

Chemistry is the study of how matter behaves and the factors that influence this behavior. An introduction to elements, compounds, and mixtures is crucial because it is a part of chemistry fundamentals. Understanding the concepts that form the classification of matter makes it easier to progress to more complex concepts of the subject. These complex concepts are often rooted in simpler but fundamental ideas.