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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.
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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… Perceiving using the 5 senses An observation using numbers AND units (measurement) • Observation – • Quantitative – • Qualitative - • Hypothesis- • Theory – • Law – 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
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) TasteChange Appearance change
Endo/Exo Notes Element • 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 - 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 +
Chemical Change * Think about Hot/Cold! Exothermic Endothermic Physical Change * Think about ENERGY! Exothermic Endothermic Exo/Endo Notes cont… HOT -energy given off H2O (l) H2O (s) + Energyor H2O (g) H2O (l) + Energy COLD -energy absorbed Energy + H2O (l) H2O (g) or Energy + H2O (s) H2O (l)