Table of Contents 15 The Nature of Matter Chapter 15: Classification of Matter 15.1: Composition of Matter 15.2: Properties of Matter 15.3: Physical vs. Chemical Changes 15.4:
Composition of Matter 15.1 Pure Substances • Materials are made of a • pure substance or a • mixture of substances. • A puresubstance, or simply a substance, is a type of matter with a fixed composition. • A substance can be either an • element or a compound.
Composition of Matter 15.1 Elements • All substances are built from atoms. If all the atoms in a substance have the same identity, that substance is an element. • The graphite in your pencil point and the copper coating of most pennies are examples of elements.
Elements Substances • Compounds H O K He N B Na S P Li Cu Be C Au Ar H2O NaCl CO2 HCl
ELEMENTS- SIMPLEST FORM OF A PURE SUBSTANCE Elements CAN NOTBE CHANGED INTO SIMPLER SUBSTANCES BY HEATING OR BY ANY CHEMICAL PROCESS - SMALLEST PART IS CALLED AN _____ *Which means – Uncutable or Indivisible Elements ATOM
- ALL ATOMS OF THE SAME ELEMENT ARE ALIKE - ATOMS OF DIFFERENT ELEMENTS ARE DIFFERENT - EACH ELEMENT IS REPRESENTED BY A CHEMICAL SYMBOL Atoms
ARE A SHORTHAND WAY OF REPRESENTING AN ELEMENT CHEMICAL SYMBOLS Symbols are always written with first letter capitalized and if there is a second letter is will always be lower case C : CARBON H : HYDROGEN Na : SODIUM O : OXYGEN Cl : CHLORINE Au : GOLD He : HELIUM N : NITROGEN Ne : NEON Pu : PLUTONIUM Es : EINSTEINIUM Eu : EUORPIUM LATIN NAMES, FAMEOUS SCIENTIST, PLACES, PLANETS, AND COUNTRIES ARE OFTEN USED TO CREATE AN ELEMENT SYMBOL
Elements • More than 20 others have been made in laboratories, but most of these are unstable and exist only for short periods of time. About 92 elements are found on Earth.
Compounds COMPOUNDS - PURE SUBSTANCES MADE UP OF MORE THAN ONE ELEMENT Joined in the same RATIO Exp: Water (H2O),Carbon Dioxide (CO2),
CAN BE BROKEN DOWN INTO SIMPLER SUB.S’ !!! PROPERTIES OF COMPOUNDS ARE DIFFERENT THAN THE PROPERTIES OF THE ELEMENTS IN THEM: NaCl Table Salt Compounds *MOLECULES - MAKE UP MOST COMPOUNDS - TWO OR MORE ATOMS CHEMICALLY BONDED TOGETHER
- IS THE SMALLEST PART OF A COMPOUND WITH ALL THE PROPERTIES OF THAT COMPOUND -ALL MOLECULES OF THE SAME COMPOUND ARE ALIKE Molecules cont.
Composition of Matter 15.1 Compounds • Can you imagine yourself putting something made from a slivery metaland a greenish-yellow, poisonous gas on your food?
Composition of Matter 15.1 Compounds • Table salt is a chemical compound that fits this description. Even though it looks like white crystals and adds flavor to food, its components—sodium and chlorine—are neither white nor salty.
Mixtures MATTER THAT CONSIST OF TWO OR MORE SUBSTANCES MIXED TOGETHER BUT NOT CHEMICALLY COMBINED !!!
Which is Which ?Substance or Mixture When you see distilled water, it's a pure substance. That fact means that there are just water molecules in the liquid.
The tap water is the mixtureand Distilled water is a Substance which is a type of Compound
There are an infinite number of mixtures. Anything you cancombineis a mixture. (even the above sentence is a mixture.) Don’t copy the statement below in yellow just read it. Think of everything you eat. Just think about how many cakes there are. Each of those cakes is made up of a different mixture of ingredients. Even the wood in your pencil is considered a chemical mixture. There is the basic cellulose of the wood, but there are also other compounds in that pencil. Mixtures – Background Info
15.1 Mixture • A Mixture, such as the pizza or soft drink shown, is a material made up of two or more substances that can be easily separated by physical means.
Composition of Matter 15.1 Heterogeneous Mixtures • Unlikecompounds, mixtures do not always contain the same proportions of the substances that make them up. • A mixture in which different materials can be distinguished easily is called a heterogeneous (he tuh ruh JEE nee us) mixture. HETEROGENEOUS MIXTURE - DOES NOT APPEAR TO BE THE SAME THROUGHOUT
Composition of Matter 15.1 Heterogeneous Mixtures • Most of the substances you come in contact with every day are heterogeneous mixtures. Some components are easy to see, like the ingredients in pizza, but others are not. • For example, the cheese in pizza is also a mixture, but you cannot see the individual components.
Composition of Matter 15.1 Homogeneous Mixtures • Soft drinks contain water, sugar, flavoring, coloring, and carbon dioxide gas. • Soft drinks in sealed bottles are examples of homogeneous mixtures. Steel is a homogeneous mixture
Homogeneous Mixtures • A homogeneous(hoh muh JEE nee us)mixturecontains two or more gaseous, liquid, or solid substances blended evenly throughout. oil or vineagar is an example of a homogeneous mixture wherein the composition is uniform throughout the entire thing
Composition of Matter 15.1 Homogeneous Mixtures • Another name for homogeneous mixtures like a cold soft drink is solution. • A solution is a homogeneous mixture of particles so small that they cannot be seen with a microscope and will never settle to the bottom of their container.
Composition of Matter 15.1 Colloids • Milk is an example of a specific kind of mixture called a colloid. • A colloid(KAH loyd) is a type of mixture with particles that are larger than those in solutions but not heavy enough to settle out.
Examples of colloids • These are just a few of the many examples of colloids, both man-made and naturally occuring. • Aerosols: • Man-made: Aerosol sprays, insecticide spray, smog. Natural: Fog, clouds. • Solid aerosol: • Natural: Smoke, dust. • Foam: • Man-made: Shaving lather, whipped cream. • Emulsions: • Man-made: Mayonnaise, cosmetic lotion, lubricants. Natural: Milk. • Sols: • Man-made: Paint, ink, detergents, rubber (a latex - also occur naturally). • Solid foams: • Man-made: Marshmallow, styrofoam, insulation, cushioning. • Gels: • Man-made: Butter, jelly. • Solid sols: • Man-made: Certain alloys. Natural: Pearl, opal
Detecting Colloids • One way to distinguish a colloid from a solution is by its appearance. • Fog appears white because its particles are large enough to scatter light. • Sometimes it is not so obvious that a liquid is a colloid. • You can tell for certain if a liquid is a colloid by passing a beam of light through it.
Composition of Matter 15.1 Detecting Colloids • A light beam is invisible as it passes through a solution, but can be seen readily as it passes through a colloid. This occurs because the particles in the colloid are large enough to scatter light, but those in the solution are not. • This scattering of light by colloidal particles is called the Tyndall effect.
Guess what this is and get a sticker! You must raise your hand.
Suspensions • Some mixtures are neither solutions nor colloids. One example is muddy pond water. • Pond water is a suspension, which is a heterogeneous mixture containing a liquid in which visible particles settle. • Fine sand in water • Paint • Dust in air • droplets of oil in air • oil and waterfine • Italian Dressing Some examples:
Composition of Matter 15.1 Suspensions • The table summarizes the properties of different types of mixtures.
Composition of Matter 15.1 Homogeneous Mixtures • Solutions remain constantly and uniformly mixed.
Section Check 15.1 Question 1 A _______ is a type of matter with a fixed composition. A. colloid B. mixture C. substance D. solution
Section Check 15.1 Answer The answer is C. A substance can be either an element or a compound.
Section Check 15.1 Question 2 How many elements are found on Earth? A. 5 B. 10 C. 30 D. 90
Section Check 15.1 Answer The answer is D. About 92 elements are found on Earth, and more than 20 have been made in laboratories.
Section Check 15.1 Question 3 How are compounds different from mixtures?
Section Check 15.1 Answer The atoms in compounds are combined in fixed proportions and cannot be separated by physical means. A mixture is made of two or more substances that can be easily separated by physical means.
Properties of Matter Part 2
Properties of Matter 15.2 Physical Properties • Any characteristic of a material that you can observe without changing the identity of the substances that make up the material is a physicalproperty. • Examples of physical properties are color, shape, size, density, melting point, and boiling point. Viscosity – The tendency of a liquid to keep from flowing.
The Greater the Viscosity = the S L O W E R the liquid moves. Viscosity usually decreases when the liquid is ______________. Viscosity heated
Which spoon would you leave in a pot of boiling water? Wooden or Metal ? Conductivity A material’s ability to allow heat (or electricity) to flow is known as Conductivity.
The ancient gold objects found in tombs in Greece were made by tapping GOLD with a hammer and punch. Gold can be shaped because it is malleable. Malleability - is the ability of a solid to be hammered without shattering. Most metals are malleable. Malleability
Properties of Matter 15.2 Appearance • How would you describe a tennis ball? You could begin by describing its shape, color, and state of matter. • You can measure some physical properties, too. For instance, you could measure the diameter of the ball.
Properties of Matter 15.2 Behavior • Some physical properties describe the behavior of a material or a substance. • Attraction to a magnet is a physical property of the substance iron. • Every substance has a specific combination of physical properties that make it useful for certain tasks.
Properties of Matter 15.2 Using Physical Properties to Separate • The best way to separate substances depends on their physical properties. • Size is one physical property often used to separate substances.
Properties of Matter 15.2 Using Physical Properties to Separate • Look at the mixture of iron filings and sand shown. • You probably won’t be able to sift out the iron filings because they are similar in size to the sand particles. What you can do is pass a magnet through the mixture.
Properties of Matter 15.2 Using Physical Properties to Separate • The magnet attracts only the iron filings and pulls them from the sand. This is an example of how a physical property, such as magnetic attraction, can be used to separate substances in a mixture.