Matter Matter n Anything that has mass and

Matter

Matter n Anything that has mass and takes up space n Extensive properties n Depend on the amount of matter considered n n Mass, volume Intensive properties n Depends on the matter considered, not the amount n Density, hardness, color, conductivity, malleability

Physical properties n Property that we see without changing the material chemically n melting point, boiling point,

States of matter n Solids n n n Definite shape and volume. Not easily compressed. Particles are tightly packed. Liquids n n Definite volume, but no definite shape. Not easily compressed.

n Gases n n No definite shape or volume. Easily compressed Vapors – gaseous form of a substance that is usually a solid or a liquid at room temp.

Physical change n A change during which some properties of a material change but the composition of the material does not. n n Cut, freeze, melt, Reversible and irreversible

Mixtures n Physical blend of two or more components n n n Heterogeneous mixture – composition is not uniform throughout n n Not made of one type of material May be heterogeneous or homogeneous Fresh milk, sand Homogeneous mixture – composition is uniform throughout n n Kool-aid, processed milk, air Solution – usually in liquids, but some are gases or solids

Mixtures n Phase – any part of a mixture that has uniform composition and properties. n Separating mixtures n n n Decant, freeze, magnetic, solubility, filtration, distillation Filtration- separate solid from a liquid in a heterogeneous mixture Distillation – liquid is boiled to produce a vapor that then condenses into a liquid. n Used to produce alcohol

Substances: elements or compounds Element – simplest form of matter that has a unique set of properties. n Compounds – a substance that contains 2 or more elements chemically bound in a fixed position n Definite composition Compounds can be broken down chemically, but elements cannot.

n Compounds cannot be broken into a simpler form through a physical change. Must go through a chemical change. n A change that produces matter with a different composition than the original matter.

Properties of compounds. n Differ greatly from the properties of the elements that make them up. n n n Na – soft grey metal, reacts violently with air Cl – yellow, green poisonous gas Na. Cl – table salt - white solid

Substance and mixtures n Substance – has a definite composition n Compounds – can broken down chemically Elements – simplest form Mixtures – varying compositions n n Homogeneous – uniform throughout mixture Heterogeneous – distinct phases

Water and salt n Names don’t tell us anything. So we use chemical symbols to represent elements and formulas to represent compounds. n Chemical symbols – one or two letter representations of elements. First letter is capital and second is always lower case.

Alchemy n Turn lead into gold n Chemical symbols based off the Latin names for elements. So they don’t always match up with the name.

Chemical reactions n Chemical properties- ability of a substance to undergo a specific chemical change. n n Can only be observed when a substance undergoes a chemical change. During a chemical change, the composition of matter always changes.

Chemical change Also called chemical reaction n The materials that start the reaction are called reactants. n The substances produced from a reaction are products. n

Recognizing a chemical change n Transfer of energy (heat, cold), change in color, the production of gas, or formation of a precipitate. n A solid that forms and settles out of a liquid mixture. n Clues don’t guarantee that a chemical reaction has taken place n Must test the composition to be sure.

Law of conservation of mass Mass is neither created nor destroyed. n In any physical or chemical change, mass is conserved n During any chemical reaction the mass of the reactants is equal to mass of products. n

Density n n Mass over volume Ratio of the mass of an object to its volume. Intensive property – depends on the composition of material not the size of the sample. Expanding due to heat causes density, in general to decrease as temperature increases.