Pure Substances and mixtures
Page 1: Introduction to Matter
Pure Substances: Defined as materials made up of only one type of particle.
Mixtures: Combinations of two or more pure substances that retain their individual properties.
Page 2: Variety of Materials
The world contains a variety of materials encountered daily, influencing our understanding of matter.
Page 3: Pure Materials
Examples of Pure Materials: Water is a quintessential example of a pure substance.
Page 4: Combinations of Substances
Some materials are mixtures, like the atmosphere, composed of various gases.
Page 5: Learning Targets
Students will learn to:
Identify and differentiate between pure substances and mixtures.
Recognize different types of mixtures.
Utilize properties of matter to identify substances.
Page 6: Classification by State
Matter can be categorized by its state:
Solid
Liquid
Gas
Page 7: Classification by Properties
Matter may also be classified by their properties:
Physical Properties: Observable without altering the substance.
Chemical Properties: Characteristics that determine how a substance interacts with other substances.
Page 8: Classification by Composition
Pure Substance: Matter with a fixed or definite composition.
Mixtures: Combinations of two or more substances without fixed compositions.
Page 9: Characteristics of Pure Substances
Defined by a specific composition, with distinct physical and chemical properties.
Made up of specific numbers of atoms or groups of atoms through chemical reactions.
Page 10: Types of Pure Substances
Elements: Simplest form of matter made of one kind of atom.
Molecules of Elements: Comprised of atoms from the same element.
Compounds: Composed of molecules containing different elements.
Page 11: Characteristics of Elements
Elements cannot be broken down by physical or chemical means.
React with each other to form new substances.
Total of 118 elements known, with 94 naturally occurring and 24 synthetic.
Page 12: The Periodic Table
The periodic table arranges all known elements according to their chemical properties, presenting a framework for understanding element relationships.
Page 13: Element Classification
Elements classified into three categories:
Metals: Left side of the periodic table, generally good conductors.
Nonmetals: Right side, typically poor conductors.
Metalloids: Elements exhibiting properties of both metals and nonmetals.
Page 14: Properties of Metals
General properties include:
Solid at room temperature (except mercury).
Lustrous appearance, malleable, ductile, good conductors of heat/electricity.
Examples: Silver, tungsten, platinum, gold.
Page 15: Unique Metal Properties
Mercury is the only metal that is liquid at room temperature, forming beads due to high surface tension.
Page 16: Properties of Nonmetals
General features:
Typically gaseous or dull solids.
Poor conductors of heat and electricity.
Examples: Sulfur, oxygen.
Page 17: Unique Nonmetal Properties
Bromine is the only liquid nonmetal at room temperature.
Page 18: Characteristics of Metalloids
Properties include:
Exhibiting both metal and nonmetal characteristics.
Moderate conductors of heat and electricity.
Commonly used in semiconductors (e.g., silicon, germanium).
Page 19: Understanding Compounds
Compounds: Mixtures of two or more different elements combined in fixed ratios through chemical reactions.
Example: Water (H2O) formed from two hydrogen atoms and one oxygen atom.
Page 20: Environmental Compounds
Many compounds occur in the environment, being produced from elemental reactions or chemical reactions among compounds.
Page 21: Stability of Compounds
Chemical bonds in compounds are stable and harder to break compared to elements.
Example: Water electrolysis separates it into oxygen and hydrogen.
Page 22: Properties vs. Composition
The properties of a compound differ significantly from those of its constituent elements.
Example: Sodium chloride (NaCl)āsodium and chlorine are harmful, yet together they form safe table salt.
Page 23: Classification of Compounds
Can be classified into:
Organic Compounds: Contain carbon and hydrogen (e.g., carbohydrates, proteins).
Inorganic Compounds: Lack carbon-hydrogen bonds (e.g., CO2, H2O, NaCl).
Page 24: Mixtures Defined
Mixtures are combinations of two or more pure substances with variable composition.
Page 25: Properties of Mixtures
Mixtures consist of pure substances combined physically without any chemical reactions.
Components maintain their individual properties when mixed (e.g., seawater).
Page 26: Classifying Mixtures
Mixtures can be classified based on component distribution:
Homogeneous Mixtures
Heterogeneous Mixtures
Page 27: Examples of Mixtures
Mixtures can include everyday items such as:
A cup of coffee
Rubbing alcohol
A puddle of mud.
Page 28: Composition of Coffee
Ingredients typically include water, coffee extract, sugar, and optionally, milk.
Page 29: Components of Wine
Wine consists primarily of alcohol and water, products from fermentation.
Page 30: Composition of Mud
A puddle consists of dirt, water, and possibly additional substances.
Page 31: Characteristics of Homogeneous Mixtures
Defined as solutions where components are indistinguishable from one another and have uniform properties.
Page 32: Examples of Homogeneous Mixtures
Include:
Saltwater
Alloys (e.g., brass)
Clean air.
Page 33: Distinguishing Mixture Types
Homogeneous Mixtures: Have a uniform composition.
Heterogeneous Mixtures: Composition is not uniform.
Page 34: Characteristics of Solutions
In solutions, one component (solute) is fully dissolved in another (solvent), creating a homogeneous mixture.
Page 35: Components of Solutions
Solutions consist of:
Solvent: Majority component, dissolving medium.
Solute: Minority component, the substance being dissolved.
Page 36: Distribution of Solute
When dissolved, solute particles disperse and become evenly distributed within the solvent, rendering them invisible to the naked eye.
Page 37: Salt Solutions
Example: In salt solutions, salt dissolves in water, becoming part of the solution.
Page 38: Solubility Concepts
Definitions:
Soluble: When substances dissolve in a solvent.
Miscible: When two liquids dissolve in each other completely.
Page 39: Dissolution Process
Solute particles are separated and spread out by solvent particles, resulting in a uniform mixture.
Page 40: Types of Solutions
Varieties based on phases:
Solid-liquid: Saltwater.
Liquid-liquid: Vinegar in water.
Gas-liquid: Carbonated drinks.
Page 41: Solid Solutions
Examples include:
Solid-solid: Brass (zinc and copper).
Liquid-solid: Amalgam (mercury and silver).
Page 42: Properties of Solutions
Solutions may be solid, liquid, or gas, exhibiting homogeneous characteristics.
Page 43: Gaseous Solutions
Illustrated by air, a mixture of gases, which is uniform when free of particles.
Page 44: Summary of Homogeneous Mixtures
Homogeneous mixtures exhibit uniform distribution and are commonly referred to as solutions.
Page 45: Heterogeneous Mixtures Definition
Composed of two or more substances whose components can be visually distinguished, with varying compositions and properties.
Page 46: Examples of Heterogeneous Mixtures
Include items such as:
Candies
Oil and water
Soup.
Page 47: Features of Heterogeneous Mixtures
Components are visually distinct and can be separated physically.
Examples include mixtures like salt and pepper or foggy air.
Page 48: Types of Heterogeneous Mixtures
Compositions may vary in appearance: two or more phases are present.
Page 49: Suspensions Explained
Suspensions: Heterogeneous mixtures with particles that do not completely dissolve and settle over time.
Page 50: Properties of Suspensions
When left undisturbed, particles of a suspension form distinct layers due to gravity.
Page 51: Colloids Explained
Colloids: Mixtures where small particles are dispersed within a medium, not settling like those in suspensions.
Page 52: Properties of Colloids
Colloid particles remain suspended for longer due to their size compared to those in suspensions.
Page 53: Classification of Colloids
Based on the physical state of the dispersing medium:
Gaseous colloids (e.g., smoke).
Liquid colloids (e.g., milk).
Solid colloids (e.g., gel).
Page 54: Examples of Gaseous Colloids
Smoke is a solid aerosol formed of very fine particles dispersed in the air.
Page 55: Examples of Liquid Colloids
Liquid aerosol: Deodorant spray, where the liquid is dispersed in air.
Page 56: Examples of Solid Colloids
Shaving foam: A foam created by air suspended in liquid soap.
Page 57: Understanding Gel and Solid foams
Gel: Liquid suspended in solid (example: Jell-O).
Solid foam: Example is styrofoam, made of gas in polymer matrix.
Page 58: Colloids Summary
Colloids not only stay suspended but also can exhibit the Tyndall effect (scattering of light).
Page 59: Characteristics of Milk
Milk as a colloid demonstrates its ability to resist settling while also scattering light.
Page 60: Heterogeneous Mixtures Overview
Composed of two or more visually distinct phases.
Can be classified further into suspensions or colloids.
Page 61: Summary of Mixing Properties
Solutions: Invisible particles easily mixed.
Suspensions: Larger particles settled out.
Colloids: Intermediate sizes, visible but remain suspended.
Page 62: Tyndall Effect Explained
Demonstrates how light behaves differently through solutions, suspensions, and colloidsāimportant for differentiating mixture types.
Page 63: Classifying Mixture Types
Define based on appearanceāuniform (homogeneous) versus non-uniform (heterogeneous) appearance.
Page 64: Review Exercise
Classify materials:
Mossy zinc
Mayonnaise
Baking soda.
Page 65: Understanding Terminology
Identify specific types from clues:
Homogeneous mixture with constant appearance.
Mixture of solute and solvent.
Mixture with varying phases and properties.
Page 66: Summary Recap
Mixtures consist of physical combinations of substances, highlighting the distinctions between homogeneous and heterogeneous types, as well as the intricacies of solutions, suspensions, and colloids.