Matter and Change Chapter 2

1. Matter and ChangeChapter 2 Objectives: You WILL be able to… ID properties of matter Define physical property and list several Differentiate 3 states of matter Describe physical change Categorize a sample of matter as a substance or a mixture Distinguish between homogeneous and heterogonous samples of matter Describe two ways that components of mixtures can be separated Explain the difference between element and compound Distinguish between a substance and a mixture ID the chemical symbols of elements and name elements given their symbols Describe what happens during a chemical change ID four possible clues a chemical change has occurred Apply the Law of Conservation of Mass to chemical reactions

2. "More than 300 years ago, in 1669, Hennig Brand, a Hamburg alchemist, like most chemists of his day, was trying to make gold. He let urine stand for days in a tub until it putrefied. Then he boiled it down to a paste, heated this paste to a high temperature, and drew the vapors into water where they could condense - to gold. To his surprise and disappointment, however, he obtained instead a white, waxy substance that glowed in the dark. Brand had discovered phosphorus, the first element isolated other than the metals and non-metals, such as gold, lead and sulphur, that were known to the ancient civilizations. The word phosphorus comes from the Greek and means light bearer."A.D.F. Toy and E.N. Walsh, Phosphorus chemistry in everyday living, 2nd. ed. (Washington: ACS, 1987)

3. 2.1 Properties of Matter • Describing Matter Characteristic Property -a specific set of observable, measurable traits which distinguish one substance from another ExtensiveProperties – Depends on the amount of matter in a sample -Volume is a measure of space occupied by an object -Mass is the amount of matter an object contains

4. Intensive Property – depends on the type of matter in a sample, NOT the amount of matter (ie. Density, color, structure, melting, boiling) • Identifying Substances Matter that has a uniform and definite composition is called a substance Physical Property – a quality or condition of a substance that can be observed or measured without changing the substances composition. • Physical Property? • 35.4 kg • Easily broken • Highly Combustible

5. States of Matter • The three states of matter we will discuss are solid, liquid, and gas. Each have their own characteristics. Solids - Have a definite shape and volume. Particles are tightly packed together Liquids – have a definite volume but no definite shape. Particles are packed more loosely. Gasses – Indefinite shape and volume. Can be compressed! Particles move around freely.

6. Gas and Vapor. Difference? • The term gas is used for substances such as oxygen which are in the gaseous state at room temperature. • Vapor describes the gaseous state of a substance that is generally a solid or a liquid at room temperature. • Plasma is a fourth state of matter which encompasses gasses under certain conditions

7. Physical Changes • Properties of the material change, but composition stays the same. • Can be classified as reversible or irreversible. Examples? • Ice melting • Tearing paper

8. 2.2 Mixtures • A mixture is a physical blend of two or more components. • Heterogeneous mixture - the composition is NOT uniform throughout. (ie. Chicken Soup) • Homogeneous mixture – the composition is uniform. Also called a Solution. (ie. Ink, air, stainless steel) NO SPECIFIC DEFINITION OR RECIPE • Phase – any part of a sample with uniform composition and properties. A well settled mixture of oil and vinegar would have how many phases? Any homogenous mixture? Interface – where two phases meet

9. Separating Mixtures • Differences in physical properties can be used to separate mixtures. -Filtration is the process that separates a solid form a liquid in a heterogeneous mixture. -Distillation is used to separate a liquid mixture of multiple liquids with different boiling points

10. Distillation

11. -Flotation separates mixtures of insoluble solids with varying densities -Fractional Crystallization separates mixtures of soluble solids which form different crystal shapes -Chromatography separates mixtures of dissolved substances based on polarity

12. 2.3 Elements and Compounds • An element is the simplest form of matter that has a unique set of properties. HAS A DEFINITION (symbol) • A compound is two or more elements chemically combined in a fixed proportion. HAS A DEFINITION (formula)

13. Breaking Down Compounds • Compounds can be broken down into its constituent substances by chemical means. • Elements can NOT be broken down by ordinary chemical means. In order to break down compounds a Chemical Change, or a change that produces matter with a different composition than the original matter, must occur.

14. Sugar  Carbon + WaterCompound Element Compound Δ • Properties of compounds are completely different than the components that make them up. • NaCl • C6H12O6 • H2O

15. Distinguishing Substances and Mixtures • If the composition of a material is fixed the material is a substance. • If the composition of a material varies the material is a mixture. Matter Substance Mixture Heterogeneous Mixture Element Homogeneous Mixture Compound

16. Symbols and Formulas • Chemical Symbols are used by the scientific community to represent each element. Each symbol may be one or two letters • Jons Jacob Berzelius created the system we use today, based on Latin names of elements. • The first letter is always capitalized (W) • The second, when used is always lowercase (Na) • Chemical Formulas are used to represent compounds (NaCl)

17. 2.4 Chemical Reactions • Chemical Changes -Words that usually indicate chemical change; produce, burn, rot, rust, decompose, ferment, explode, corrode, and sometimes bubble The ability of a substance to undergo chemical change is called a Chemical Property. During a chemical change the composition of matter ALWAYS changes. (not the case for physical change)

18. A chemical change is also called a Chemical Reaction • During a chemical reaction one or more substances change into one or more new substances. • A Reactant is a substance present at the start of a reaction. • A Product is a substance that is produced in the reaction.

19. How do I know if a chemical reaction is taking place? • There are several possible indicators of a chemical reaction. • Change in color • Evolution of a gas • Formation of a precipitate, a solid settling from a liquid • Emission of energy (heat, cold, or light) *Energy is always involved in chemical reactions*

20. The Law of Conservation of Mass • During any chemical reaction, the mass of the products is always equal to the mass of the reactants. • Therefore, mass cannot be created or destroyed.

21. What is Energy? • Energy is the ability to do work or cause change. Types of energy include • Heat- Measured by changes in temperature, released by burning • Mechanical - KINETIC = energy of motion, and POTENTIAL = energy of position (stored energy) • Electrical - based on a flow of electrons (e-'s) • Chemical - a kind of potential energy, used in bonding, etc. • Radiant - all of the "waves": X-ray, radio, TV, microwave, solar, light, UV, IR… • Nuclear - energy stored in the nucleus of the atom, fission/fusion

22. Law of Conservation of Energy • Energy can be converted from one form to another but cannot be created or destroyed. • The terms matter and energy are interchangeable as theorized by Einstein • E=mc2 The amount of energy is directly proportional to the mass of body