2.1 Properties of Matter

2. 2.1 Properties of Matter • _____________________ – a change during which some properties of the substance changes but the composition doesn’t • May change the shape, but the identity of the substance stays the same • Are reversible or irreversible • _________________________- a change that produces matter with a different composition than the original matter • Are irreversible

3. 2.2 Mixtures • _______________________ – a physical blend of two or more substances. • _______________________ – particles are not evenly distributed throughout the mixture • Ex: chicken noodle soup • _______________________ – particles are evenly distributed throughout • Also called a SOLUTION • They occur in PHASES

4. 2.2 Mixtures • _______________________________ – separated by differences in physical properties • ______________________ – separated by a difference in boiling points of substances in a mixture • Homogeneous mixture • ______________________ – separation of a mixture along a stationary substance • Homogeneous mixture • _________________ – separates a solid from a liquid • Heterogeneous mixture • ________________________ – partial evaporation of a liquid produces crystals of high quality • Homogeneous mixture

5. 2.3 Elements and Compounds • Substances are classified as either elements or compounds • ________________ – simplest form of matter that has a unique set of properties • _________________ – substance that contains two or more elements chemically combined in a fixed proportion. • Compounds can be broken down into simpler substances, but elements cannot

6. 2.3 Elements and Compounds • In order to break down compounds, a chemical reaction must take place. • This produces matter with a different composition than the original matter. • Distinguishing between substances & mixtures • If the composition of the substance is fixed, the material is a substance. If the composition of a material may vary, the material is a mixture.

7. 2.3 Elements and Compounds Matter SubstanceMixture Element CompoundHomogenous Heterogenous mixture mixture Can be separated physically

8. 2.3 Elements and Compounds • Symbols and formulas • Chemists use symbols to represent elements, and chemical formulas to represent compounds • Element symbols are either one or two letters, with the first letter always being capitalized, and the second letter, when present, always lower case. • Many element names come from their Latin roots

9. 2.4 Chemical Reactions • ________________________ – the ability of a substance to undergo a specific chemical change. • During a chemical change (chemical reaction), the composition of matter always changes. • ________________________ – when one or more substances changes into one or more new substances • A substance that enters into a chemical reaction is a ______________________________. • A substance the is produced as a result of a chemical reaction is a ___________________________.

10. 2.4 Chemical Reactions • Clues a chemical reaction has taken place • Transfer of energy • ________________________________ – when energy is given off to the surroundings • _________________________________ – when energy is absorbed from the surroundings • Color change • Production of a gas • Formation of a _______________________ • _______________________ – when a solid forms when to liquids combine

11. 2.4 Chemical Reactions • Conservation Laws • Law of Conservation of _________ –energy cannot be created nor destroyed, but can change forms • Law of Conservation of __________– mass cannot be created nor destroyed, but can change forms • The total amount of mass and energy present before the rxn must be the equal to the amount present after the rxn • In all reactions mass and energy are conserved.