What Are Elements, Compounds, and Mixtures? Key Differences and Examples - CBSE Class Notes Online

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Mixtures, Compounds and Elements- The Fundamental Building Blocks of Matter

Matter is the substance that makes up everything around us, from the air we breathe to the water we drink and the materials we use every day.

Classification of Matter- Elements, Compounds and Mixtures

Chemistry is the study of the structures, physical properties and chemical properties of material substances. To understand the diversity of matter, we classify it into three main categories-

Elements
Compounds
Mixtures

Elements are pure substances made up of only one type of atom, while compounds are pure substances formed by chemically combining two or more different elements in a fixed ratio. Mixtures, on the other hand, are physical combinations of two or more substances that retain their original properties and can be separated by physical methods.

These three forms of matter are fundamental to chemistry, as they form the basis for studying chemical reactions, material properties and the behavior of substances in various environments. This article provides a comprehensive overview of elements, compounds and mixtures, including their definitions, properties, examples and methods of separation.

Also Check – Properties of Matter: Physical, Chemical, and Functional Explained With Examples

What are Elements?

Element Definition-

Elements are the simplest chemical substances, made up of only one type of atom and cannot be broken down into simpler substances by physical or chemical means. Each element is defined by its atomic number, which represents the number of protons in its atomic nucleus. This atomic number is unique to each element and forms the basis for its position in the Periodic Table of Elements.

Key Characteristics of Elements-

Pure substances with only one type of atom
Cannot be broken down into simpler substances by ordinary chemical reactions
Exhibit unique physical and chemical properties
Exist as atoms, molecules, or ions depending on their bonding and state

Isotopes-

Atoms of the same element can have different numbers of neutrons, leading to isotopes. For example, Carbon has three naturally occurring isotopes-

Carbon-12 (¹²C) – Stable, most common form
Carbon-13 (¹³C) – Stable, used in chemical tracing
Carbon-14 (¹⁴C) – Radioactive, used in radiocarbon dating

Also Check – Nuclear Transmutation: How Elements Change in Nature and Science

Types of Elements-

Elements can be broadly classified into three categories-

Metals- Typically lustrous, conductive, malleable and ductile (e.g., Iron (Fe), Gold (Au), Copper (Cu)).
Non-Metals- Generally poor conductors, brittle and non-lustrous (e.g., Oxygen (O), Carbon (C), Sulfur (S)).
Metalloids- Exhibit properties of both metals and non-metals (e.g., Silicon (Si), Boron (B), Arsenic (As)).

Also Check- The Periodic Table of Elements: What It Is and How It Works

Examples of Elements-

Element Name	Symbol	Atomic Number	Category
Hydrogen	H	1	Non-Metal
Carbon	C	6	Non-Metal
Sodium	Na	11	Metal
Lead	Pb	82	Metal
Platinum	Pt	78	Metal
Silicon	Si	14	Metalloid

Examples of Elements

Elemental Forms-

Elements can exist in different forms depending on their bonding and physical state-

Atoms- Single, independent particles (e.g., Helium (He))
Molecules- Two or more atoms of the same element bonded together (e.g., Oxygen gas (O₂), Nitrogen gas (N₂))
Ions- Charged particles formed by gaining or losing electrons (e.g., Sodium ion (Na⁺), Chloride ion (Cl⁻))

Interesting Fact-
As of now, there are 118 known elements, of which the first 94 are naturally occurring, while the remaining 24 are synthetic, created in laboratories through nuclear reactions.

Chart of Elements -Names, Symbols and Atomic Numbers

Names, symbols, and atomic numbers identify chemical elements. Each element has a unique name, a one- or two-letter symbol (e.g., H for hydrogen) and an atomic number representing the number of protons in its nucleus. These identifiers help classify elements in the periodic table and predict chemical behavior in reactions and compounds.

Also Check – What Are Chemical Elements? A Complete Guide for Students

What are Compounds?

Compound Definition-

A compound is a pure chemical substance formed when two or more elements chemically combine in a fixed ratio by mass. Compounds are characterized by a specific chemical formula and distinct physical and chemical properties that differ from the elements that form them. Unlike mixtures, the components of a compound are chemically bonded, meaning they can only be separated through chemical reactions.

Chemical Formulas-

Compounds are represented by their chemical formulas, which show the exact ratio of their constituent atoms. For example-

Water (H₂O) – Two atoms of hydrogen chemically bonded with one atom of oxygen.
Carbon Dioxide (CO₂) – One atom of carbon chemically bonded with two atoms of oxygen.
Sodium Chloride (NaCl) – One atom of sodium chemically bonded with one atom of chlorine.

Types of Compounds-

Compounds can be broadly classified into two main types based on their bonding-

Molecular Compounds- Atoms are bonded through covalent bonds, where they share electrons. Examples include-
- Water (H₂O)
- Methane (CH₄)
- Carbon Dioxide (CO₂)
Ionic Compounds (Salts)- Atoms are bonded through ionic bonds, where one atom donates an electron to another, creating positively and negatively charged ions. Examples include-
- Sodium Chloride (NaCl)
- Magnesium Oxide (MgO)
- Calcium Chloride (CaCl₂)

Examples of Common Compounds-

Compound Name	Chemical Formula	Type
Water	H₂O	Molecular
Carbon Dioxide	CO₂	Molecular
Sodium Chloride	NaCl	Ionic
Sulfuric Acid	H₂SO₄	Molecular
Methane	CH₄	Molecular
Ammonia	NH₃	Molecular
Acetic Acid	C₂H₄O₂	Molecular

Examples of Common Compounds-

Key Properties of Compounds-

Fixed chemical composition by mass
Different physical and chemical properties from their constituent elements
Chemically bonded elements
Can only be separated through chemical reactions

Interesting Fact-
The properties of a compound are often completely different from the properties of the elements that form it. For example, water (H₂O) is a liquid essential for life, while its constituent elements, hydrogen and oxygen, are both highly flammable gases.

What are Mixtures?

Mixture Definition-

A mixture is a physical combination of two or more substances-whether elements, compounds, or both-in which each component retains its own chemical identity. The substances in a mixture are not chemically bonded and their proportions can vary, meaning the composition is not fixed. As a result mixtures display the properties of their individual constituents and can be separated through physical processes.

Key Characteristics of Mixtures-

Variable Composition- The proportion of each component can differ without altering the nature of the mixture.
No Chemical Bonds- Components are physically combined without the formation of chemical bonds.
Retained Properties- Each substance maintains its original physical and chemical characteristics.
Separable by Physical Means- Components can be separated using techniques such as filtration, distillation, or evaporation.
No Definite Formula- Mixtures do not possess a fixed chemical formula, as the combination ratio is not constant.

TYpes of Mixtures

Mixtures are broadly classified into two main categories based on the uniformity of their composition and the size of their particles-

1. Homogeneous Mixtures (Solutions)

A homogeneous mixture has a uniform composition throughout, meaning its components are distributed evenly at the molecular level. The particles in a homogeneous mixture are so small that they are not visible to the naked eye and the mixture appears as a single phase.

Characteristics of Homogeneous Mixtures-

Uniform composition throughout
Particles are typically less than 1 nanometer in size
Do not scatter light (no Tyndall effect)
Cannot be separated by simple filtration
Stable over time (particles do not settle)

Examples of Homogeneous Mixtures-

Saltwater (NaCl in H₂O)- A mixture of salt dissolved in water
Air- A mixture of gases like oxygen, nitrogen, carbon dioxide and argon
Alloys- Metallic mixtures like brass (copper and zinc) and stainless steel (iron, chromium and carbon)
Vinegar- A mixture of acetic acid in water

2. Heterogeneous Mixtures

A heterogeneous mixture has a non-uniform composition, where the individual components remain physically separate and can often be identified by the naked eye or under a microscope. These mixtures have more than one phase, with distinct boundaries between the different substances.

Characteristics of Heterogeneous Mixtures-

Non-uniform composition
Particles are typically larger than 1 nanometer, often visible
Exhibit the Tyndall effect (light scattering) if the particles are small enough
Components can be easily separated by physical methods
Often unstable, with particles settling over time

Examples of Heterogeneous Mixtures-

Sand and Iron Filings- Physically distinct particles that can be separated by a magnet
Oil and Water- Immiscible liquids with distinct layers
Granite- A rock composed of different minerals like quartz, feldspar and mica
Salad- A mixture of vegetables with varying textures and flavors

Special Types of Mixtures

Within the broad categories of homogeneous and heterogeneous mixtures, there are several special types, including solutions, colloids and suspensions–

a. Solutions (Homogeneous Mixtures)

Particle size- < 1 nanometer
Do not scatter light
Completely dissolved particles
Examples- Sugar in water, salt in water, tincture of iodine (iodine in alcohol)

b. Colloids (Heterogeneous Mixtures)

Particle size- 1 to 1000 nanometers
Exhibit the Tyndall effect (scatter light)
Particles do not settle over time
Examples- Milk, fog, blood, jelly, mayonnaise

c. Suspensions (Heterogeneous Mixtures)

Particle size- > 1000 nanometers
Particles settle over time
Can be separated by filtration
Exhibit the Tyndall effect when freshly mixed
Examples- Muddy water, sand in water, paint, flour in water

Difference Between Solutions, Colloids and Suspensions

Property	Solutions	Colloids	Suspensions
Particle Size	< 1 nm	1 – 1000 nm	> 1000 nm
Visibility	Invisible	Not visible	Visible
Tyndall Effect	No	Yes	Yes (if fresh)
Stability	Stable	Stable	Unstable
Separation	Not possible	Not possible	Possible by filtration
Examples	Saltwater, Vinegar	Milk, Fog, Jelly	Muddy Water, Sand in Water

Difference Between Solutions, Colloids and Suspensions – Tabular Format

Separation Techniques for Mixtures

Mixtures can be separated into their individual components through various physical methods depending on the type and properties of the mixture-

Filtration- Separates insoluble solids from liquids (e.g., sand from water)
Distillation- Separates liquids based on boiling points (e.g., alcohol from water)
Centrifugation- Separates particles based on density (e.g., blood components)
Magnetic Separation- Uses magnets to separate magnetic materials (e.g., iron filings from sand)
Chromatography- Separates substances based on their different rates of movement through a medium (e.g., separating plant pigments)
Decantation- Separates liquids from insoluble solids by pouring (e.g., water from sand)

Differences Between Mixtures, Compounds and Elements

Differences between mixtures, compounds and elements is crucial in chemistry, as each represents a distinct form of matter with unique properties and behaviors. Let’s explore these differences in detail.

1. Difference Between Mixtures, Compounds and Elements

Property	Elements	Compounds	Mixtures
Definition	Pure substances made up of only one type of atom.	Pure substances formed by the chemical combination of two or more elements in a fixed ratio.	Physical combinations of two or more substances that retain their original properties.
Composition	Consists of only one kind of atom.	Consists of two or more different elements chemically bonded.	Consists of two or more elements or compounds physically mixed.
Chemical Bonds	No chemical bonds present.	Elements are chemically bonded (ionic, covalent, or metallic bonds).	No chemical bonding; components are physically combined.
Separation	Cannot be broken down into simpler substances by chemical or physical methods.	Can only be separated into elements by chemical reactions.	Can be separated by physical methods like filtration, distillation, or centrifugation.
Properties	Unique set of physical and chemical properties.	Has distinct properties different from the elements that form it.	Retains the properties of its individual components.
Representation	Represented by chemical symbols (e.g., O, Na, Fe).	Represented by chemical formulas (e.g., H₂O, CO₂, NaCl).	Not represented by fixed chemical formulas.
Energy Changes	No energy changes when atoms form.	Involves energy changes during bond formation or breaking.	No significant energy changes when mixed.
Examples	Oxygen (O₂), Gold (Au), Sodium (Na)	Water (H₂O), Carbon Dioxide (CO₂), Sodium Chloride (NaCl)	Air, Salad, Sea Water, Alloy (e.g., brass)

Difference Between Mixtures, Compounds and Elements – Tabular Format

2. Difference Between Compounds and Mixtures

While both compounds and mixtures consist of two or more substances, the way they combine and the resulting properties differ significantly-

Property	Compound	Mixture
Definition	Pure substances formed by the chemical combination of two or more elements in a fixed ratio.	Physical combinations of two or more substances that retain their original properties.
Chemical Bonds	Components are chemically bonded (ionic or covalent bonds).	No chemical bonding; components are physically combined.
Composition	Fixed, with elements in a definite ratio by mass.	Variable, with no fixed composition.
Properties	Has distinct physical and chemical properties different from its constituent elements.	Retains the physical and chemical properties of its components.
Separation	Can only be separated into elements by chemical reactions.	Can be separated by physical methods like filtration, evaporation, or centrifugation.
Energy Changes	Involves energy changes during bond formation and breaking.	Usually does not involve significant energy changes.
Homogeneity	Always homogeneous at the molecular level.	Can be homogeneous (solution) or heterogeneous (suspension, colloid).
Examples	Water (H₂O), Carbon Dioxide (CO₂), Sodium Chloride (NaCl)	Air, Salad, Saltwater, Concrete

Difference Between Compounds and Mixtures – Tabular Format

3. Difference Between Elements and Compounds

Property	Element	Compound
Definition	Pure substances made up of only one type of atom.	Pure substances formed by the chemical combination of two or more elements in a fixed ratio.
Basic Unit	Atom	Molecule or ion
Chemical Bonds	No chemical bonds (only single type of atoms).	Atoms are chemically bonded (ionic, covalent, or metallic bonds).
Composition	Consists of a single type of atom.	Consists of two or more different types of atoms chemically combined.
Separation	Cannot be broken down into simpler substances by chemical or physical means.	Can be broken down into simpler substances by chemical reactions.
Representation	Represented by chemical symbols (e.g., O, Na, Fe).	Represented by chemical formulas (e.g., H₂O, NaCl, CO₂).
Properties	Unique physical and chemical properties.	Has distinct properties different from the elements that form it.
Examples	Oxygen (O₂), Gold (Au), Sodium (Na)	Water (H₂O), Sodium Chloride (NaCl), Carbon Dioxide (CO₂)

Difference Between Elements and Compounds – Tabular Format

FAQs on Mixtures, Compounds and Elements

General FAQs

What is an element in chemistry?
An element is a pure substance consisting of only one type of atom. It cannot be broken down into simpler substances by chemical or physical means. Examples include oxygen (O), gold (Au) and iron (Fe).
What are compounds and how are they formed?
A compound is a pure substance formed when two or more elements chemically combine in a fixed ratio. For example, water (H₂O) is formed by the combination of hydrogen and oxygen.
What is a mixture?
A mixture is a physical combination of two or more substances (elements or compounds) that retain their original properties and can be separated by physical methods. Examples include air, salad and saltwater.
How are elements, compounds and mixtures different from each other?
Elements consist of only one type of atom, compounds are chemically bonded combinations of elements and mixtures are physical combinations of different substances without chemical bonding.
What is the periodic table and why is it important?
The Periodic Table is a systematic arrangement of all known elements, organized by their atomic numbers and chemical properties. It helps predict the behavior of elements in chemical reactions.
What is the difference between atoms, molecules and ions?
- Atoms are the smallest units of an element.
- Molecules are groups of atoms bonded together.
- Ions are charged particles formed when atoms gain or lose electrons.
How do elements differ from compounds?
Elements consist of a single type of atom, while compounds are made up of two or more different elements chemically bonded in a fixed ratio.
Can an element be a mixture?
No, an element is a pure substance and cannot be a mixture.
How many elements are there in the periodic table?
There are 118 known elements, of which 94 are naturally occurring, while the rest are synthetic.
What is the significance of the atomic number of an element?
The atomic number represents the number of protons in an atom’s nucleus, defining the element’s identity.

Element-Specific FAQs

What are the basic properties of elements?
Elements have unique physical and chemical properties, such as melting point, boiling point, density and atomic mass.
How are elements classified?
Elements are classified into metals, non-metals and metalloids based on their physical and chemical properties.
What are metals, non-metals and metalloids?
- Metals are shiny, conductive and malleable (e.g., iron, gold).
- Non-metals are brittle and poor conductors (e.g., oxygen, sulfur).
- Metalloids have properties of both metals and non-metals (e.g., silicon, boron).
Why is hydrogen considered a non-metal?
Hydrogen behaves like a non-metal in its physical state and chemical behavior, forming covalent bonds.
What is the difference between metals and non-metals?
Metals are good conductors, malleable and ductile, while non-metals are poor conductors, brittle and lack metallic luster.
What are some common examples of elements?
- Metals- Iron (Fe), Copper (Cu), Silver (Ag)
- Non-Metals- Oxygen (O), Carbon (C), Nitrogen (N)
- Metalloids- Silicon (Si), Arsenic (As), Boron (B)
What are isotopes?
Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons. For example, Carbon-12, Carbon-13 and Carbon-14.
Are all elements naturally occurring?
No, only 94 elements are naturally occurring, while the remaining 24 are synthetic, created in laboratories.
What are noble gases and why are they inert?
Noble gases (e.g., helium, neon, argon) are inert because they have a full valence electron shell, making them chemically stable.

Compound-Specific FAQs

What is a compound in chemistry?
A compound is a pure substance formed by chemically combining two or more different elements in a fixed ratio.
What are the main types of chemical bonds?
- Ionic Bonds- Transfer of electrons (e.g., NaCl)
- Covalent Bonds- Sharing of electrons (e.g., H₂O)
- Metallic Bonds- Free movement of electrons in a lattice of metal atoms (e.g., Fe, Cu)
What is the difference between ionic and covalent compounds?
- Ionic Compounds- Formed by the transfer of electrons (e.g., NaCl)
- Covalent Compounds- Formed by sharing electrons (e.g., H₂O)
Can compounds be broken down into simpler substances?
Yes, compounds can be broken down into elements through chemical reactions.
How are the properties of compounds different from their elements?
Compounds have unique properties that are different from the elements that form them. For example, water (H₂O) is a liquid, while hydrogen and oxygen are gases.

Mixture-Specific FAQs

What is the difference between homogeneous and heterogeneous mixtures?
- Homogeneous Mixtures- Uniform composition (e.g., saltwater, air).
- Heterogeneous Mixtures- Non-uniform composition (e.g., salad, sand in water).
What is a solution?
A homogeneous mixture where the solute is completely dissolved in the solvent.
What is a colloid?
A mixture where small particles are dispersed in a medium, exhibiting the Tyndall effect (e.g., milk, fog).
What is a suspension?
A heterogeneous mixture where large particles settle over time (e.g., muddy water).
Why are mixtures not considered pure substances?
Mixtures contain multiple substances that retain their original properties and can be physically separated.

Comparison FAQs

30. What is the difference between elements and compounds?
Elements are pure substances made up of only one type of atom, while compounds are pure substances formed by the chemical bonding of two or more different elements in a fixed ratio. For example, oxygen (O₂) is an element, while water (H₂O) is a compound.

31. What is the difference between compounds and mixtures?
Compounds have a fixed composition, with elements chemically bonded together, resulting in new physical and chemical properties. Mixtures, on the other hand, consist of two or more substances that are physically combined without any chemical bonding, retaining their original properties. For example, sodium chloride (NaCl) is a compound, while saltwater is a mixture.

32. What is the difference between homogeneous and heterogeneous mixtures?

Homogeneous Mixtures- Have a uniform composition throughout, like saltwater or air.
Heterogeneous Mixtures- Have a non-uniform composition with distinct phases, like salad or sand in water.

33. How do solutions differ from colloids and suspensions?

Property	Solutions	Colloids	Suspensions
Particle Size	< 1 nm	1-1000 nm	> 1000 nm
Visibility	Invisible	Not visible	Visible
Tyndall Effect	No	Yes	Yes (if fresh)
Stability	Stable	Stable	Unstable
Separation	Not possible	Not possible	Possible by filtration
Examples	Saltwater, Vinegar	Milk, Fog, Jelly	Muddy Water, Sand in Water

34. Why are compounds considered pure substances while mixtures are not?
Compounds have a fixed chemical composition and are formed by chemical bonding, resulting in a single, pure substance with distinct properties. Mixtures, on the other hand, retain the properties of their individual components and can vary in composition.

35. What is the difference between atoms and molecules?

Atoms- The smallest unit of an element, consisting of protons, neutrons and electrons.
Molecules- Groups of two or more atoms chemically bonded together, which can be the same or different elements. For example, O₂ (oxygen molecule) and H₂O (water molecule).

36. Why are the properties of mixtures different from those of compounds?
In mixtures, the individual components retain their original physical and chemical properties, while in compounds, the elements chemically combine to form a new substance with completely different properties. For instance, hydrogen and oxygen gases form liquid water when chemically combined.

Application FAQs

37. Why are alloys considered mixtures?
Alloys are mixtures because they consist of two or more metals (or a metal and a nonmetal) physically combined without forming chemical bonds. For example, brass is a mixture of copper and zinc.

38. What are some real-world examples of elements, compounds and mixtures?

Elements- Oxygen (O₂), Gold (Au), Iron (Fe)
Compounds- Water (H₂O), Carbon Dioxide (CO₂), Sodium Chloride (NaCl)
Mixtures- Air (mixture of gases), Salad (mixture of vegetables), Seawater (mixture of salts and water)

39. How are mixtures used in the food industry?
Mixtures are used in food processing to create flavors, textures and nutritional content. For example, salad dressings (emulsions), soups (suspensions) and carbonated drinks (gas-liquid solutions).

40. Why are compounds important in medicine?
Compounds form the basis of many pharmaceuticals, such as aspirin (C₉H₈O₄), penicillin and paracetamol, which have specific chemical structures that allow them to interact with the body in targeted ways.

41. How are elements, compounds and mixtures used in construction?

Elements- Steel (Fe), used for structural support
Compounds- Cement (CaO), used in concrete
Mixtures- Concrete, a mixture of cement, sand, gravel and water

42. What is the role of chemistry in environmental science?
Chemistry helps understand pollutants, analyze water quality and develop solutions for reducing carbon emissions, recycling and waste management.

43. How do chemical compounds help in industrial processes?
Chemical compounds are essential for manufacturing, energy production and materials science. For example, ammonia (NH₃) is used in fertilizers and sulfuric acid (H₂SO₄) is used in battery production.

44. What is the importance of separating mixtures in daily life?
Separation processes like filtration, distillation and centrifugation are crucial for purifying water, refining petroleum and processing food.