Matter and Change

Matter Anything that has mass and takes up space

Mass The amount of matter an object contains Mass is NOT weight. Weight is the effect of gravity on mass.

Pure Substance Any matter that has a fixed composition and definite properties Elements and Compounds are pure substances Compounds cannot be separated by physical means

Physical Property Quality or condition of a substance that can be observed or measured w/o changing the substance’s composition Color Solubility Odor Hardness Density Melting pt. Freezing pt.

States of Matter

Gases High energy Free to spread in all directions Fill the area in which it is contained Collisions between atoms occurs frequently Collisions against walls creates Pressure

Liquids Take shape of container Particles are close but not as tightly connected as solids The viscosity of the liquid is determined by the attraction of the particles in the liquid. Oil is more viscous than water

Solids Low energy Have rigid structures, no room to change position Does not need a container to have a shape Particles are held closely together by strong attractions

Physical Changes Way to change matter w/o altering it chemically Grind Boil Freeze Bend Dissolve Melt

Heterogeneous Mixture Substances are not uniformly mixed Examples Flour in water Hamburger Salad

Homogeneous Mixture Substances are uniformly mixed and stay the same throughout Examples Salt water Gasoline

Distillation Way of separating liquids The liquid is vaporized and then cooled to be collected Every substance has a unique boiling pt.

Elements Simplest forms of matter that can exist under normal laboratory conditions Elements CANNOT be separated into simpler substances by chemical means Oxygen Carbon Hydrogen Sodium Nickel Sulfur

Compounds Two or more elements chemically combined Substances that can be separated only be chemical means Sodium chloride Sucrose Water Calcium carbonate

Chemical Symbol Symbols have been used to represent elements since the original four were discussed (Earth, wind, fire, water) Shorthand way to write chemical formulas First letter is ALWAYS capitalized Second letter is ALWAYS lower case Subscript numbers represent proportions of the elements

Chemical Symbol (Cont.) Sucrose Elements Carbon Hydrogen Oxygen C12H22O11 Subscripts 12 Carbon Atoms 11 Oxygen Atoms 22 Hydrogen Atoms

Chemical Reaction One or more substances change into new substances Reactant – starting substance Product – substance formed 2H2 + O2 H2O Reactant Product

Conservation of Mass Mass is neither created nor destroyed During any chemical rxn, the quantity of matter is unchanged. The mass of products always equals the mass of reactants