Chemistry Intro. Notes Chemistry – Matter – Mass – Weight – Volume - Energy – Kinetic – Potential – Study of matter and energy All of the “stuff” in the universe A quantity or amount of matter Mass with a force or attraction like gravity A measurement of the space something occupies Ability to do work Energy of motion Energy of position

Chemistry Intro. Notes cont… Observation – Quantitative – Qualitative - Hypothesis - Theory – Law – Perceiving using the 5 senses An observation using numbers AND units (measurement) An observation using the senses (hard to quantify exa..green) Educated guess made after observations Possible explanation of a law A statement about nature to which there are NO known exceptions Exa…the sun rises in the east and sets in the west Scientific Method: Observation Hypothesis Experiments Theory

Chemistry Intro. Notes cont… Matter Mixtures Pure Substances (Homogeneous) -Separated by physical means -Separated by chemical means Heterogeneous Homogeneous Element (symbol) Compound (formula) -unevenly distributed -evenly distributed (solution) every piece is the same type of atom (p.t.) Exa… Al foil -2 or more atoms chemically combined covalent ionic molecules (non-metals) Ions (metal ion + Non-metal ion) atom Protons Neutrons Electrons Quark Quark

Physical Properties Physical Property – Examples: Defines the physical nature of the substance Color * Volume * Freezing point Texture * Taste * Sublimation point Size * Boiling point Odor * Evaporation point Density * Condensation point Sound * Melting point

Example: …for water (H2O) Physical Changes Physical Changes – Example: …for water (H2O) A change without change of identity Melting Point Boiling Point Solid Liquid Gas Freezing Point Condensation Point O °C 1OO °C

Chemical Properties Chemical Properties – Examples: * flammable (combustible) – * oxidizer – * reactive – * corrosive – * explosive - Define the chemical nature of the substance will burn Will combine with oxygen (exa…rust) Will create bubbles while chemically changing (exa…with acids and bases) Will eat away by chemical action (exa..acids and bases) Will produce a rapid chemical change with a violent burst of energy

Chemical Changes Chemical change – Evidence of a Chemical change: 1. 2. 3. 4. 5. 6. 7. 8. Change with change of identity Light Odor Change Color change (careful!! This can be physical!) Heat Change Reaction, gas given off (NOT dissolving) Precipitate ie “chunky stuff” (filtration) Taste Change Appearance change

Endo/Exo Notes A symbol represents an ___________ A formula represents a ___________ __________ represents a chemical change exa… A + B  C + D exa… iron + sulfur  iron (II) sulfide Law of Conservation of Matter - Element Compound Equation Reactants  Products Fe + S  FeS Matter cannot be created nor destroyed. (It just changes places)

Exo/Endo Notes cont… There are 2 kinds of Energy Changes in a chemical reaction: Exothermic – Endothermic – Energy “exits” (goes out) Exa… X + Y  Z + Energy Energy “enters” (goes in) Exa… A + B  C Energy +

Exo/Endo Notes cont… Chemical Change * Think about Hot/Cold! Exothermic Endothermic Physical Change * Think about ENERGY! Exothermic Endothermic HOT -energy given off H2O (l)  H2O (s) + Energy or H2O (g)  H2O (l) + Energy COLD -energy absorbed Energy + H2O (l)  H2O (g) or Energy + H2O (s)  H2O (l)