Ch.1 Introduction: Matter and MeasurementChemistry: The study of matter and the changes that matter undergoes1.1 The Study of ChemistryThe Atomic and Molecular Perspective of Chemistry:- Matter: Anything that has mass and occupies space- Property: Any characteristic that allows us to recognize a particular type of matter and to distinguish it from other types- Elements: About 100 substances that compose matter- Atoms: Smallest building blocks of matter- Properties of matter relate to the types of atoms (composition) and their arrangements (structure).- Molecules: Two or more atoms joined in specific shapes- Macroscopic realm and submicroscopic realm to be analyzedWhy Study Chemistry?:- Chemistry is part of health care, natural resource conservation, the environment, and energy supply1.2 Classifications of Matter- Matter characterized by physical state (solid, liquid, or gas) and composition (element, compound, or mixture)States of Matter:- States of matter: Gas, liquid or solid- Gas: (vapor) No fixed volume or shape; can be compressed or expandedo Molecules far apart and moving at high speedso When compressed, frequency of molecule collision is increased- Liquid: Distinct volume; assumes shape of container it occupieso Molecules packed together, moving rapidly, sliding over each other- Solid: Definite shape and definite volumeo Molecules tightly togetherPure Substances:- Most substances are not chemically pure, but can be separated into pure substances.- Pure substance: (or substance) Matter with distinct properties and a composition that does not vary from sample to sample (ex. Water)- All substances are elements or compounds.- Elements: Substances that cannot be decomposed into simper substanceso Each element has only one kind of atom.- Compounds: Substances composed of two or more elements- Mixtures: Combinations of two or more substances in which each substance retains its chemical identityElements:- 118 known elements, varying greatly in abundance- Symbol for each element has two letters with first capitalized- Periodic tableCompounds:- Most elements interact with other elements to form compounds.- Ex. Hydrogen gas burns in oxygen gas to form water.- Pure water consists of 11% hydrogen and 89% oxygen by mass.- H and O exist as diatomic molecules.- Law of constant composition (definite proportions): The elemental composition of a compound is always the same.o French chemist Joseph Louis Proust in 1800o Pure compounds have same composition and properties under same conditions regardless of sourceMixtures:- Each substance in mixture retains its chemical identity and properties.- Unlike pure substance (fixed composition), composition of mixtures varies- Components: Substances within a mixture- Heterogeneous: Vary in composition, properties, and appearance- Homogeneous: Uniform mixtures (also called solutions)1.3 Properties of Matter- Physical properties: Properties able to be observed without changing the identity and composition of the substance (ex. Color, odor, density, melting point, boiling point, and hardness)- Chemical properties: Describe the way a substance changes, or reacts, to form other substances (ex. flammability)- Intensive properties: Do not depend on amount of sample examined used to identify substances(ex. temp, melting point)- Extensive properties: Depend on amount of sample (ex. mass, volume)Physical and Chemical Changes:- Physical change: Substances changes physical appearance, but not composition.- All changes of state are physical changes.- Chemical change (reaction): Substance transformed into chemically diff substance.Separation of Mixtures:- Difference in properties of substances is usedo Use of magneto Filtration: Dissolve one of the substanceso Distillation: Separation by heating, then condensationo Chromatography: Depends on ability of substances to adhere to the surfaces of solids1.4 Units of Measurements- Many properties of matter are quantitative, or associated with numbers.- Units must be specified, and must be of the metric system.Scientific Method:- Theory: Model with predictive powers that accounts for all scientific observationso Always possibility of flawso An explanation of what occurs in nature- Scientific law: A statement of what repeatedly occurs in natureSI Units:- SI units: Metric unites used in scientific measurements, from French Systeme International d’Unites- Seven base units- Prefixes used to indicate decimal fractions or multiples of various unitsLength and Mass:- Mass: Measure of the amount of material in an object- SI unit of length is meter, and that of mass is kilogramTemperature:- Temperature: Measure of the hotness or coldness of an object- Physical prop that determines heat flow- Heat flows from high to low temperatures- Celsius scale: 0°C as water’s freezing point and 100°C as boiling point- Kelvin scale: SI temp scale using Kelvin, or Ko Zero on kelvin is absolute zero, the lowest attainable tempo K= °C + 273.15o °C=59(° F−32)o° F=95(° C)+32Derived SI Units:- Derived unit: Unit obtained by multiplication or division of one or more of the base units- Ex. Speed unit= m/sVolume:- Ex. length cubed, 1 L= 1 dm3, 1 mL= 1 cm3- Syringes, burettes, and pipettes have greater precision with measuring liquidsDensity:- Density: The amount of mass in a unit volume of a substanceo Density= massvolume- Expressed as g/cm3 or g/mL- Density of water= 1.00 g/mL- Density is temp dependent.Chemistry in the New:- Clean energy from fuel cells: energy of chemical reaction converted directly into electrical energy- Regulation of greenhouse gaseso Greenhouse gases: Substances with the potential to alter global climate bc of ability to trap long-wavelength radiation at Earth’s surface- Anesthesiao Injected into blood stream for medical procedureso Drugs have therapeutic index, or ration of smallest fatal dose to smallest dose that gives the desired effect1.5 Uncertainty in Measurement- Exact numbers: Values are known exactly- Inexact numbers: Values with some uncertaintyo Numbers obtained by measurement always inexactPrecision and Accuracy:- Precision: Measure of how closely individual measurements agree with each other- Accuracy: How closely individual measurements agree with the correct/true value- Standard deviation: Reflects how much individual measurements differ from averageSignificant Figures:- Significant figures: All digits of a measured quantity, including uncertain one- Greater number of sig figs= greater precision-