What is KMT?: What is KMT? Based on the research of Robert Boyle (1627 – 1691) A theory that envisions molecules in motion Best describes properties and behaviors of gases * Imagines particles of a gas like billiard balls, moving and crashing into each and the walls of a container in a three-dimensional space.


Kinetic Molecular Theory*: Kinetic Molecular Theory* All matter consists of extremely tiny particles (atoms and molecules) that are in constant motion The different states of matter are due to the different spacing and energy of the particles An additional aspect of the kinetic-molecular theory is the dependence on temperature - Increasing temperature corresponds to faster and faster motions of atoms and molecules and increased spacing. The basic principles of KMT are theoretical and begin to break down under certain circumstances? KMT is better at describing matter in higher energy states (gases, for example)


Slide4: The Three States of Matter Based upon particle arrangement Based upon energy of particles Based upon distance between particles Matter - anything that occupies space and has mass


Classifying Matter: Classifying Matter States of Matter Solid - has a rigid shape and a fixed volume that changes very little with temperature and pressure Liquid - like solids have a fixed volume but no definite shape (take on the shape of the container) Gas - no fixed volume - volume determined by the size of the container - the volume of a gas varies greatly with temperature and pressure


Solid: Solid definite volume definite shape atoms are packed together in fixed positions strong attractive forces between atoms only vibrate in place


Liquid: Liquid definite volume indefinite shape atoms are close together atoms can overcome attractive forces to flow


Gases: Gases indefinite volume indefinite shape atoms move very quickly atoms are far apart pretty weak attractive forces


Slide9: States of Matter Solid Liquid Gas Definite Volume? YES YES NO Definite Shape? YES NO NO Temp. increase Small Expans. Small Expans. Large Expans. Com-pressible? NO NO YES


Changes of State: Changes of State


Slide11: Solid Liquid Gas


Matter: Matter All matter is composed of 100 or so __ELEMENTS_____ A substance that cannot be separated into simpler substances by a chemical change; simplest type of pure substance. The building block of matter is the __ATOM_____ The smallest particle of an element that retains the chemical identity of the element. Atoms can combine to form COMPOUNDS


Elements and Compounds = Pure Substances: Elements and Compounds = Pure Substances Element = Matter that is composed of only one type of atom Currently 116 elements are known to exist Only about 90 of these are found in nature - the remainder were synthesized by scientist The elements are listed in the Periodic Table Compound= Compounds are composed of molecules with more than 1 type of atom Molecules are defined combinations of atoms that are chemically attached (“chemically bonded”):


Pure Substances: Pure Substances Elements- simplest kind of matter Cannot be broken down into simpler All one kind of atom. Compounds are substances that can be broken down by chemical methods When they are broken down, the pieces have completely different properties than the compound. Made of molecules- two or more atoms stuck together


Mixtures? Made up of two substances. Variable composition.Mixtures can be;: Mixtures? Made up of two substances. Variable composition. Mixtures can be; Homogeneous= same composition throughout. Every part keeps its properties Kool-aid, air, salt water Heterogeneous= mixture is not the same from place to place. Chocolate chip cookie, gravel, soil.


Solutions: Solutions Homogeneous mixture Mixed molecule by molecule Can occur between any state of matter. Solid in liquid- Kool-aid Liquid in liquid- antifreeze Gas in gas- air Solid in solid - brass Liquid in gas- water vapor


Solutions : Solutions solvent what does the dissolving larger volume solute what is being dissolved smaller volume


Examples of Mixtures: Examples of Mixtures


Classification of Matter: Classification of Matter Matter can be classified as either Pure or Mixture: Pure Element: composed of only one type of atom Composed of either individual atoms or molecules (e.g. O2) Compound: composed of more than one type of atom Consists of molecules Mixture Homogeneous: uniform throughout, appears to be one thing pure substances solutions (single phase homogeneous mixtures) Suspensions (multi-phase homogeneous mixtures) Heterogeneous: non-uniform, contains regions with different properties than other regions


Compound or Mixture: Compound or Mixture Compound Mixture One kind of piece- Molecules More than one kind - Molecule or atoms Making is a chemical change Making is a physical change Only one kind Variable composition


Which is it?: Which is it?


Separation Techniques: Separation Techniques Filtration- solid part is trapped by filter paper and the liquid part runs through the paper Vaporization- where the liquid portion is evaporated off to leave solid


Separation Techniques: Separation Techniques Decanting- when liquid is poured off after solid has settled to bottom Centrifuge- machine that spins a sample very quickly so that components with different densities will separate


Separation Techniques: Separation Techniques Paper Chromatography- used to separate mixtures because different parts move quicker on paper than other


Properties of Matter: Properties of Matter Physical Characteristics can be observed without altering the identity of the substance Volume Mass Maleability, ductility, conductivity etc… Chemical Characteristics cannot be observed without altering the identity of the substance Flammability Tendency to corrode Reactivity Etc…


Physical Properties (continued): Physical Properties (continued) Extensive and Intensive Properties Extensive properties depend on the amount of a substance present. Examples are mass and volume. Intensive properties are those that do not depend on the amount of substance (e.g., melting point, boiling point, and density) Ice melts at 0oC no matter whether you have an ice cube or an iceberg


Changes Matter Can Undergo:: Changes Matter Can Undergo: Physical Change: Solid ? Liquid Melting Liquid ? Gas Boiling or Evaporating Gas ? Liquid Condensation Solid ? Gas Sublimation Gas ? Solid Sublimation Liquid ? Solid Freezing, solidifying


Changes Matter Can Undergo:: Changes Matter Can Undergo: Chemical Change: Rusting, rotting, burning, chemical reaction…


Physical Changes & Chemical Changes: Physical Changes & Chemical Changes Physical Changes : A change that changes appearances, without changing the composition. Examples? Chemical changes - a change where a new form of matter is formed. Also called chemical reaction. Examples? Not phase changes Ice is still water.


Physical and Chemical Change: Physical and Chemical Change Chemical changes (or chemical reactions) involve transformation of one or more substances (reactants) into one or more different substances (products)


Chemical changes often involve a transfer of energy!: Chemical changes often involve a transfer of energy!


Chemical Change: Chemical Change A symbolic representation of chemical changes is called a chemical equation.


Distinguishing Chemical from Physical Change: Distinguishing Chemical from Physical Change Did the change produce a different substance? Was there a color change? Is there a different density? Is there a melting or boiling point change? Did something precipitate ( solid formed) out of solution? Did a gas or smoke form? Was there (a lot of ) energy released or absorbed