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Class 9 Science NCERT Notes – Chapter 2: Is Matter Around Us Pure? (PDF, MindMap, Q&A, Quizzes)
ByAKS
Chapter 2 (Chemistry): Is Matter Around Us Pure? – Class 9 NCERT Science Detailed Study Notes.
1. Understanding Purity and Mixtures
1.1 Pure Substances vs. Mixtures
In everyday language, “pure” often means having no adulteration. However, in a scientific context, the definition is more precise.
- Scientific Definition of Pure: A substance is considered pure if all of its constituent particles are the same in their chemical nature. A pure substance consists of a single type of particle and is a single form of matter.
- Examples: Sodium chloride (salt) and sugar are pure substances. They cannot be broken down into their chemical constituents by physical processes.
- Definition of a Mixture: A mixture is constituted by more than one kind of pure substance (elements or compounds) mixed in any proportion. Most matter around us, such as sea water, minerals, and soil, exists as mixtures.
- Examples: Milk is a mixture of water, fat, and proteins. Soft drinks and soil are also mixtures.
1.2 Types of Mixtures
Mixtures are classified based on the uniformity of their composition.
- Homogeneous Mixtures (Solutions): These mixtures have a uniform composition throughout. The particles are evenly distributed at a microscopic level.
- Properties: Uniform composition, can have variable composition (e.g., different shades of copper sulphate solution).
- Examples: Salt dissolved in water, sugar dissolved in water, lemonade, soda water, air, and alloys.
- Heterogeneous Mixtures: These mixtures contain physically distinct parts and have a non-uniform composition. The different components are often visible.
- Properties: Non-uniform composition, physically distinct parts.
- Examples: A mixture of sodium chloride and iron filings, salt and sulphur, oil and water, and soil.
2. Solutions, Suspensions, and Colloids
2.1 Solutions (True Solutions)
A solution is a homogeneous mixture of two or more substances.
- Components:
- Solvent: The component that dissolves the other component, usually present in the larger amount. (e.g., water in a sugar solution).
- Solute: The component that is dissolved in the solvent, usually present in a lesser quantity. (e.g., sugar in a sugar solution).
- Types and Examples:
- Solid in Liquid: Sugar in water; Tincture of iodine (iodine solid in alcohol liquid).
- Gas in Liquid: Aerated drinks like soda water (carbon dioxide gas in water liquid).
- Gas in Gas: Air (a mixture of gases, primarily 78% nitrogen and 21% oxygen).
- Solid in Solid: Alloys (e.g., Brass, which is approximately 30% zinc and 70% copper). Alloys are considered mixtures because they show the properties of their constituents and can have a variable composition.
- Properties of a Solution:
- It is a homogeneous mixture.
- Particles are smaller than 1 nm (10⁻⁹ m) in diameter and cannot be seen by the naked eye.
- Does not scatter a beam of light, so the path of light is not visible (no Tyndall effect).
- It is stable; solute particles do not settle down when left undisturbed.
- Solute particles cannot be separated by filtration.
- Concentration of a Solution:
- Saturated Solution: A solution that has dissolved the maximum amount of solute it is capable of dissolving at a given temperature.
- Unsaturated Solution: A solution where the amount of solute is less than the saturation level.
- Solubility: The amount of solute present in a saturated solution at a specific temperature. Different substances have different solubilities at the same temperature.
- Methods of Expressing Concentration:
- Mass by mass percentage:
(Mass of solute / Mass of solution) × 100 - Mass by volume percentage:
(Mass of solute / Volume of solution) × 100 - Volume by volume percentage:
(Volume of solute / Volume of solution) × 100
- Mass by mass percentage:
2.2 Suspensions
A suspension is a heterogeneous mixture in which solute particles do not dissolve but remain suspended throughout the medium.
- Properties of a Suspension:
- It is a heterogeneous mixture.
- Particles are large enough to be seen by the naked eye.
- Scatters a beam of light, making its path visible.
- It is unstable; solute particles settle down when left undisturbed.
- Components can be separated by the process of filtration.
2.3 Colloidal Solutions (Colloids)
A colloidal solution is a mixture where the particles are uniformly spread. It appears homogeneous but is actually a heterogeneous mixture.
- Components:
- Dispersed Phase: The solute-like component or dispersed particles.
- Dispersing Medium: The component in which the dispersed phase is suspended.
- Properties of a Colloid:
- It is a heterogeneous mixture.
- Particle size is too small to be seen individually by the naked eye.
- Particles are large enough to scatter a beam of light (Tyndall effect). This effect is seen when sunlight passes through the canopy of a dense forest (mist acts as a colloid).
- It is quite stable; particles do not settle down.
- Components cannot be separated by filtration but can be separated by a special technique called centrifugation.
- Common Examples of Colloids:
| Dispersed Phase | Dispersing Medium | Type | Example(s) |
| Liquid | Gas | Aerosol | Fog, clouds, mist |
| Solid | Gas | Aerosol | Smoke, automobile exhaust |
| Gas | Liquid | Foam | Shaving cream |
| Liquid | Liquid | Emulsion | Milk, face cream |
| Solid | Liquid | Sol | Milk of magnesia, mud |
| Gas | Solid | Foam | Foam, rubber, sponge, pumice |
| Liquid | Solid | Gel | Jelly, cheese, butter |
| Solid | Solid | Solid Sol | Coloured gemstone, milky glass |
3. Physical vs. Chemical Changes
- Physical Properties: Characteristics that can be observed and specified without changing the substance’s chemical identity, such as colour, hardness, rigidity, density, melting point, and boiling point.
- Physical Change: A change that occurs without altering the chemical composition of the substance. A new substance is not formed.
- Examples: Interconversion of states (ice to water to steam), cutting trees, melting butter, boiling water, dissolving salt in water, and making a fruit salad.
- Chemical Change (Chemical Reaction): A process where one substance reacts with another, resulting in a change in chemical composition and the formation of new substances with new chemical properties.
- Examples: Burning (combustion), rusting of an almirah, passing an electric current through water to break it down into hydrogen and oxygen, and burning of paper and wood.
- Dual Changes: Some processes involve both. For example, during the burning of a candle, the melting of wax is a physical change, while the burning of the wax vapour is a chemical change.
4. Types of Pure Substances
Pure substances are classified into elements and compounds based on their chemical composition.
4.1 Elements
An element is a basic form of matter that cannot be broken down into simpler substances by chemical reactions. Robert Boyle first used the term in 1661, and Antoine Laurent Lavoisier provided the first experimentally useful definition.
- Facts about Elements:
- More than 100 elements are known; 92 are naturally occurring.
- The majority are solid at room temperature.
- Eleven are gases at room temperature.
- Two are liquids at room temperature: mercury and bromine.
- Classification of Elements:
- Metals: Have lustre (shine), are silvery-grey or golden-yellow, conduct heat and electricity, are ductile (can be drawn into wires), malleable (can be hammered into sheets), and sonorous (make a ringing sound). Examples: gold, silver, copper, iron. Mercury is the only metal that is liquid at room temperature.
- Non-metals: Display a variety of colours, are poor conductors of heat and electricity, and are not lustrous, sonorous, or malleable. Examples: hydrogen, oxygen, iodine, carbon, bromine, chlorine.
- Metalloids: Have intermediate properties between metals and non-metals. Examples: boron, silicon, germanium.
4.2 Compounds
A compound is a substance composed of two or more elements chemically combined in a fixed proportion.
- Properties of Compounds:
- Elements react to form new compounds.
- The composition is always fixed.
- The new substance has properties that are totally different from its constituent elements.
- Constituents can only be separated by chemical or electrochemical reactions, not by physical methods.
4.3 Comparing Mixtures and Compounds
| Feature | Mixtures | Compounds |
| Formation | Elements or compounds just mix; no new compound is formed. | Elements react chemically to form new compounds. |
| Composition | Has a variable composition. | The composition of the new substance is always fixed. |
| Properties | Shows the properties of its constituent substances. | The new substance has totally different properties from its constituents. |
| Separation | Constituents can be separated fairly easily by physical methods. | Constituents can only be separated by chemical or electrochemical reactions. |
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Q&A Section
Short-Answer Questions (25 Questions)
Answer each question in 2-3 sentences.
- What is the difference between the common person’s definition of “pure” and a scientist’s definition?
- Based on the scientific definition, why is milk considered a mixture and not a pure substance?
- Define a homogeneous mixture and provide two examples.
- What are the key characteristics of a heterogeneous mixture?
- What are the two main components of a solution called? Describe each.
- What is an alloy? Why is it considered a mixture and not a compound?
- List three key properties of a true solution.
- Explain the difference between a saturated and an unsaturated solution.
- What is meant by the “solubility” of a substance?
- A solution contains 40 g of salt in 320 g of water. What is the mass of the solution?
- Define a suspension and state whether it is stable or unstable.
- How can the components of a suspension be separated?
- What is a colloidal solution? Why does it appear homogeneous?
- Explain the Tyndall effect and give a real-world example of where it can be observed.
- What are the “dispersed phase” and “dispersing medium” in a colloid?
- Can colloids be separated by filtration? If not, what technique can be used?
- What is a physical change? Provide an example.
- Define a chemical change and explain how it differs from a physical change.
- The burning of a candle involves both physical and chemical changes. Identify one of each.
- Who was the first scientist to provide an experimentally useful definition of an element? What was the definition?
- List three characteristic properties of metals.
- Name two elements that are liquid at room temperature.
- What is a metalloid? Give one example.
- Define a compound, highlighting its key characteristics regarding composition and properties.
- According to the text, what is the fundamental difference in how mixtures and compounds are formed?
Multiple-Choice Questions (20 Questions)
- Which of the following is considered a pure substance by a scientist?
- a) Milk b) Sea water c) Sugar d) Soil
- Brass, an alloy of zinc and copper, is an example of a:
- a) Compound b) Solid solution c) Heterogeneous mixture d) Suspension
- In a sugar-water solution, water is the:
- a) Solute b) Solvent c) Dispersed phase d) Suspension medium
- Which of the following has particles smaller than 1 nm in diameter?
- a) A solution b) A suspension c) A colloid d) Muddy water
- The scattering of a beam of light by colloidal particles is known as:
- a) Filtration b) Centrifugation c) The Tyndall effect d) Evaporation
- Which of the following is a heterogeneous mixture?
- a) Air b) Soda water c) Oil and water d) Tincture of iodine
- A solution that has dissolved as much solute as it is capable of dissolving at a given temperature is called:
- a) Unsaturated b) Concentrated c) Saturated d) Dilute
- Which of the following is an example of a chemical change?
- a) Melting of butter b) Boiling water c) Dissolving salt in water d) Rusting of iron
- Which property is NOT characteristic of metals?
- a) They are sonorous b) They are poor conductors of electricity c) They are ductile d) They have lustre
- According to the text, a substance composed of two or more elements chemically combined in a fixed proportion is a:
- a) Mixture b) Colloid c) Compound d) Solution
- What is the type of colloid where a solid is dispersed in a liquid?
- a) Emulsion b) Foam c) Aerosol d) Sol
- In the mixture of iron filings and sulphur powder (Group I experiment), the components can be separated by:
- a) A chemical reaction b) Centrifugation c) A physical method (like using a magnet) d) Heating
- Which of the following is NOT a pure substance?
- a) Iron b) Calcium oxide c) Air d) Mercury
- The particles of a suspension will:
- a) Pass through a filter paper b) Settle down when left undisturbed c) Be smaller than 1 nm d) Remain stable indefinitely
- Fog is an example of which type of colloid?
- a) Sol (solid in liquid) b) Emulsion (liquid in liquid) c) Aerosol (liquid in gas) d) Foam (gas in liquid)
- The interconversion of states (e.g., ice to water) is an example of a:
- a) Chemical change b) Physical change c) Chemical reaction d) Compound formation
- Elements with intermediate properties between metals and non-metals are called:
- a) Alloys b) Colloids c) Metalloids d) Compounds
- Which statement about compounds is TRUE?
- a) They have a variable composition. b) They show the properties of their constituent elements. c) They can be separated by physical methods. d) They have properties entirely different from their constituents.
- Air is a homogeneous mixture with its two main constituents being:
- a) Oxygen (78%) and Nitrogen (21%) b) Nitrogen (78%) and Oxygen (21%) c) Carbon Dioxide (78%) and Oxygen (21%) d) Oxygen (50%) and Nitrogen (50%)
- A mixture of milk and water will:
- a) Not scatter light b) Show the Tyndall effect c) Settle down after a few minutes d) Be separable by simple filtration
Essay Questions (10 Questions)
- Compare and contrast the properties of solutions, suspensions, and colloids. Discuss their appearance, particle size, stability, effect on a beam of light, and filterability.
- Explain the difference between a mixture and a compound using the experiment involving iron filings and sulphur powder as a detailed example.
- Describe the three methods for expressing the concentration of a solution mentioned in the text. Then, solve the following problem: A solution is prepared by dissolving 40 g of common salt in 320 g of water. Calculate its concentration in terms of mass by mass percentage.
- Define and differentiate between physical and chemical changes. Provide at least three distinct examples for each, as listed in the text, and explain why each example fits its category.
- What is an element? Describe the classification of elements into metals, non-metals, and metalloids, listing at least four characteristic properties for both metals and non-metals.
- Explain the concept of solubility and its relation to saturated solutions. Using the data provided for potassium nitrate, describe how a change in temperature affects its solubility.
- What is the Tyndall effect? Describe the conditions under which it is observed and explain the phenomenon using the examples of a beam of light entering a room and sunlight passing through a forest canopy.
- Classify the following as elements, compounds, or mixtures, and justify your answer for each: (a) Sodium, (b) Soil, (c) Sugar solution, (d) Calcium carbonate, (e) Air, (f) Methane.
- An alloy like brass is considered a mixture, even though it is a solid. Explain why, based on the definition and properties of mixtures provided in the text.
- Describe the different types of colloids based on the state of the dispersed phase and the dispersing medium. Provide one example for each of the following types: aerosol, emulsion, foam, and sol.
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Answer Keys
Key for Short-Answer Questions
- A common person considers a substance “pure” if it has no adulteration. A scientist defines a pure substance as one where all constituent particles have the same chemical nature.
- Milk is a mixture because it is composed of different substances like water, fat, and proteins that are not chemically combined. A pure substance, by contrast, consists of only a single type of particle.
- A homogeneous mixture is one that has a uniform composition throughout its bulk. Examples include salt dissolved in water and air.
- A heterogeneous mixture has a non-uniform composition and contains physically distinct parts. Its different components can often be seen separately, like in a mixture of oil and water.
- The two components are the solvent and the solute. The solvent is the component present in the larger amount that does the dissolving, while the solute is the component in the lesser quantity that gets dissolved.
- An alloy is a mixture of two or more metals, or a metal and a non-metal. It is considered a mixture because it exhibits the properties of its constituents and can have a variable composition.
- Three key properties of a solution are that it is a homogeneous mixture, its particles are smaller than 1 nm and cannot be seen, and it is stable, meaning the solute does not settle out.
- A saturated solution contains the maximum possible amount of dissolved solute at a given temperature. An unsaturated solution contains less solute than the saturation level and can still dissolve more.
- Solubility is the amount of solute present in a saturated solution at a specific temperature. It represents the maximum amount of a substance that can dissolve in a given solvent at that temperature.
- The mass of the solution is the sum of the mass of the solute and the mass of the solvent. Therefore, the mass of the solution is 40 g + 320 g = 360 g.
- A suspension is a heterogeneous mixture in which solid particles are dispersed in a liquid but do not dissolve. It is unstable because the particles settle down when left undisturbed.
- The components of a suspension can be separated by the physical process of filtration. This is possible because the suspended particles are large enough to be caught by the filter paper.
- A colloidal solution is a heterogeneous mixture where particles are uniformly spread, making it appear homogeneous. It appears this way because the particle size is relatively small compared to a suspension.
- The Tyndall effect is the scattering of a beam of visible light by the particles of a colloid. It can be observed when a fine beam of light enters a dark room through a small hole, illuminating dust particles in the air.
- The “dispersed phase” is the solute-like component consisting of the colloidal particles. The “dispersing medium” is the solvent-like component in which the dispersed phase is suspended.
- No, colloids cannot be separated by filtration because their particles are too small. A special technique called centrifugation can be used to separate the colloidal particles.
- A physical change is a change in the physical properties of a substance without any change in its chemical composition. An example is the melting of butter in a pan.
- A chemical change involves a change in the chemical composition of matter, leading to the formation of new substances. Unlike a physical change, it is not just a change of state or form.
- In a burning candle, the melting of the solid wax into liquid wax is a physical change. The combustion of the wax vapour, which produces new substances like carbon dioxide and water, is a chemical change.
- Antoine Laurent Lavoisier was the first scientist to establish an experimentally useful definition. He defined an element as a basic form of matter that cannot be broken down into simpler substances by chemical reactions.
- Three characteristic properties of metals are that they have lustre (shine), they are good conductors of heat and electricity, and they are ductile (can be drawn into wires).
- The two elements that are liquid at room temperature are mercury and bromine.
- A metalloid is an element that has intermediate properties between those of metals and non-metals. An example is silicon.
- A compound is a pure substance made of two or more elements chemically combined in a fixed proportion. A key characteristic is that the resulting compound has properties totally different from its constituent elements.
- Mixtures are formed when elements or compounds just mix together without any chemical reaction or formation of a new substance. Compounds are formed when elements react chemically with one another.
Key for Multiple-Choice Questions
- c) Sugar
- b) Solid solution
- b) Solvent
- a) A solution
- c) The Tyndall effect
- c) Oil and water
- c) Saturated
- d) Rusting of iron
- b) They are poor conductors of electricity
- c) Compound
- d) Sol
- c) A physical method (like using a magnet)
- c) Air
- b) Settle down when left undisturbed
- c) Aerosol (liquid in gas)
- b) Physical change
- c) Metalloids
- d) They have properties entirely different from their constituents.
- b) Nitrogen (78%) and Oxygen (21%)
- b) Show the Tyndall effect
Key for Essay Questions
- Comparison of Solutions, Suspensions, and Colloids:
- Solutions are homogeneous mixtures with particles smaller than 1 nm. They appear clear and do not scatter light (no Tyndall effect). They are stable, meaning the solute does not settle, and cannot be separated by filtration.
- Suspensions are heterogeneous mixtures with large particles visible to the naked eye. They appear cloudy or opaque and scatter light, making its path visible. They are unstable as the particles settle down upon standing and can be easily separated by filtration.
- Colloids are heterogeneous mixtures that appear homogeneous. Their particle size is intermediate between solutions and suspensions. They are stable and exhibit the Tyndall effect. They cannot be separated by filtration but can be by centrifugation.
- Mixture vs. Compound (Iron and Sulphur Experiment): A mixture is formed by physically combining substances without a chemical reaction. In the experiment, Group I mixed iron filings and sulphur powder. The result was a mixture that retained the properties of its constituents; for example, the iron was still attracted to a magnet. The components could be separated by physical means. A compound is formed when elements react chemically in a fixed proportion. Group II heated the iron and sulphur mixture, causing a chemical reaction. The result was a new substance, iron sulphide, which is a compound. This compound had entirely new properties—it was not magnetic and did not behave like iron or sulphur—and could not be separated by physical means.
- Concentration of a Solution: The three methods mentioned are:
- Mass by mass percentage:
(Mass of solute / Mass of solution) × 100 - Mass by volume percentage:
(Mass of solute / Volume of solution) × 100 - Volume by volume percentage:
(Volume of solute / Volume of solution) × 100Problem Solution: Mass of solute (salt) = 40 g Mass of solvent (water) = 320 g Mass of solution = Mass of solute + Mass of solvent = 40 g + 320 g = 360 g Mass percentage = (Mass of solute / Mass of solution) × 100 = (40 / 360) × 100 = 11.1%.
- Mass by mass percentage:
- Physical vs. Chemical Changes: A physical change is one that alters the physical properties of a substance (like state, shape, or size) but does not change its chemical identity. No new substance is formed. Examples from the text include: cutting of trees, melting of butter in a pan, and boiling of water to form steam. A chemical change, or chemical reaction, results in the formation of one or more new substances with different chemical properties and compositions. The original substance is permanently altered. Examples from the text include: rusting of almirah, passing electric current through water to break it down, and burning of paper and wood.
- Elements and their Classification: An element is a basic form of matter that cannot be broken down into simpler substances by chemical reactions.
- Metals have lustre (shine), are good conductors of heat and electricity, are ductile, and are malleable. They are also sonorous, making a ringing sound when hit.
- Non-metals are poor conductors of heat and electricity, are not lustrous, sonorous, or malleable, and they display a variety of colours.
- Metalloids are elements that exhibit properties intermediate between those of metals and non-metals, such as boron and silicon.
- Solubility and Saturated Solutions: A saturated solution is one that cannot dissolve any more solute at a given temperature. The amount of solute required to create this saturated solution is called its solubility at that temperature. The data for potassium nitrate shows that as temperature increases, its solubility increases significantly. At 283 K, its solubility is 21 g per 100 g of water, while at 353 K, its solubility rises to 167 g per 100 g of water. This demonstrates a direct relationship between temperature and the solubility of this salt.
- The Tyndall Effect: The Tyndall effect is the phenomenon of light scattering by particles in a colloid, which makes the path of a light beam visible. This occurs because the colloidal particles are large enough to interfere with and scatter the light waves. The effect is not seen in true solutions because their particles are too small. Real-world examples include the visible path of sunlight entering a room through a small opening, where the light is scattered by dust particles (a colloid of solid in gas), and the visible sunbeams in a dense forest, where light is scattered by tiny water droplets in mist (a colloid of liquid in gas).
- Classification of Substances:
- (a) Sodium: Element. It is a basic form of matter that cannot be broken down further by chemical reactions.
- (b) Soil: Mixture. It is a heterogeneous mixture of various minerals, organic matter, and other substances with a non-uniform composition.
- (c) Sugar solution: Mixture. It is a homogeneous mixture (a solution) of sugar (solute) dissolved in water (solvent).
- (d) Calcium carbonate: Compound. It is a substance composed of the elements calcium, carbon, and oxygen chemically combined in a fixed ratio.
- (e) Air: Mixture. It is a homogeneous mixture of gases like nitrogen, oxygen, etc., in variable proportions.
- (f) Methane: Compound. It is a substance composed of carbon and hydrogen atoms chemically bonded in a fixed ratio (CH₄).
- Why Alloys are Mixtures: An alloy like brass is considered a mixture for two key reasons based on the text. First, it shows the properties of its constituents (zinc and copper), which is a characteristic of mixtures. Second, it can have a variable composition; for example, brass is approximately 30% zinc and 70% copper, but this ratio can be varied, which is another defining property of a mixture, unlike compounds which have a fixed composition.
- Types of Colloids and Examples:
- Aerosol: A colloid with a gas as the dispersing medium. An example is fog, where liquid water droplets are dispersed in gas (air).
- Emulsion: A colloid where a liquid is dispersed in another liquid. An example is milk, where liquid fat globules are dispersed in water.
- Foam: A colloid where a gas is dispersed in a liquid. An example is shaving cream.
- Sol: A colloid where a solid is dispersed in a liquid. An example is mud or milk of magnesia.
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Glossary of Key Terms
- Aerosol: A colloid in which the dispersing medium is a gas and the dispersed phase is either a solid or a liquid.
- Alloys: Homogeneous mixtures of two or more metals or a metal and a non-metal, which cannot be separated by physical methods.
- Centrifugation: A special separation technique used to separate colloidal particles from a mixture.
- Chemical Change: A change that brings about a change in the chemical properties of matter, resulting in the formation of new substances. Also called a chemical reaction.
- Colloid: A heterogeneous mixture where particles are too small to be seen with the naked eye but large enough to scatter light. The particles are uniformly spread and do not settle.
- Compound: A pure substance composed of two or more elements chemically combined in a fixed proportion.
- Concentrated Solution: A comparative term for a solution that has a relatively large amount of solute dissolved in it.
- Concentration: The amount of solute present in a given amount (mass or volume) of a solution.
- Dispersed Phase: The solute-like component or particles in a colloid.
- Dispersing Medium: The solvent-like component in which the dispersed phase is suspended in a colloid.
- Ductile: The property of metals that allows them to be drawn into thin wires.
- Element: A basic form of matter that cannot be broken down into simpler substances by chemical reactions.
- Emulsion: A type of colloid in which a liquid is dispersed in another liquid.
- Filtration: A process used to separate insoluble particles from a liquid, such as separating the components of a suspension.
- Foam: A type of colloid in which a gas is dispersed in a liquid or a solid.
- Gel: A type of colloid in which a liquid is dispersed in a solid.
- Heterogeneous Mixture: A mixture that has a non-uniform composition and contains physically distinct parts.
- Homogeneous Mixture: A mixture that has a uniform composition throughout.
- Malleable: The property of metals that allows them to be hammered into thin sheets.
- Metalloids: Elements that have properties intermediate between those of metals and non-metals.
- Metals: A class of elements that are typically lustrous, ductile, malleable, sonorous, and good conductors of heat and electricity.
- Mixture: A substance constituted by more than one kind of pure form of matter (elements or compounds).
- Non-metals: A class of elements that are typically poor conductors of heat and electricity and are not lustrous, ductile, or malleable.
- Physical Change: A change in the physical properties of a substance without a change in its chemical composition.
- Pure Substance: A substance consisting of a single type of particle, where all constituent particles have the same chemical nature.
- Saturated Solution: A solution that has dissolved the maximum amount of solute it can at a given temperature.
- Sol: A type of colloid in which a solid is dispersed in a liquid.
- Solubility: The amount of solute present in a saturated solution at a given temperature.
- Solute: The component of a solution that is dissolved, usually present in a lesser quantity.
- Solution: A homogeneous mixture of two or more substances.
- Solvent: The component of a solution that dissolves the other component, usually present in a larger amount.
- Sonorous: The property of metals that causes them to make a ringing sound when hit.
- Suspension: A heterogeneous mixture in which solute particles do not dissolve but remain suspended and eventually settle down.
- Tyndall Effect: The scattering of a beam of light by colloidal particles, which makes the path of light visible.
- Unsaturated Solution: A solution in which the amount of solute is less than the saturation level.