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CHEMISTRY. The study of the structure of matter and how that structure affects the properties and behavior of matter. magnesium hydroxide Mg(OH) 2. sucrose C 12 H 22 O 11. sulfuric acid H 2 SO 4. sodium bicarbonate NaHCO 3. ammonia NH 3 ( aq ). calcium hypochlorite Ca( OCl ) 2.
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CHEMISTRY The study of the structure of matter and how that structure affects the properties and behavior of matter.
magnesium hydroxide Mg(OH)2 sucrose C12H22O11 sulfuric acid H2SO4 sodium bicarbonate NaHCO3 ammonia NH3(aq) calcium hypochlorite Ca(OCl)2 5% acetic acid, CH3COOH
mercury, Hg diamonds, C cast iron skillet, Fe table salt, NaCl charcoal, C
Matter bromine vapor • Anything that has mass and occupies space • Has one of three physical states: • Gas (no fixed volume or shape). Gases are also called vapors. iodine vapor liquid bromine chlorine gas solid iodine
Matter – Physical States water H2O mercury Hg Liquid (fixed volume but no fixed shape)
Matter – Physical States Solid (fixed volume and fixed shape)
Matter – Changes of State Changes of state are physical changes • vaporization (liquidgas) • condensation (gasliquid)
Matter – Changes of State Changes of state are physical changes • melting (solidliquid) • freezing (liquidsolid)
Matter – Changes of State Changes of state are physical changes • sublimation (solidgas) dry ice • deposition (gassolid)
Matter • Changes of identity are called chemical changes (chemical reactions) • Matter combines with other matter to form a new substance: 2Na(s) + Cl2(g) 2NaCl(s) • Matter breaks up into new substances: 2KClO3(s) + heat (Δ) 2KCl(s) + 3O2(g)
Element The most basic form of matter that exists under ordinary conditions. An element cannot be broken down into a simpler substance. • Helium, Neon • Fluorine, Chlorine • Sodium, Potassium
Atom • The smallest particle of an element. (more on atoms later)
Chemical Symbols • Each element has a one- or two-letter abbreviation as a symbol. • Some abbreviations are obvious. • Oxygen • Carbon • Sulfur • Hydrogen • Calcium • Bromine • Fluorine • Aluminum O C S H Ca Br F Al
Chemical Symbols • Symbols and names don’t have to be similar. • Sodium • Potassium • Copper • Iron • Lead • Mercury • Gold • Tin Na natrium kalium cuprum ferrum plumbum hydrargyrum aurum stannum K Cu Fe Pb Hg Au Sn
Interesting Element Names • Bismuth (German for white mass) • Iridium (iris is Latin for rainbow) • Rubidium (rubidius is Latin for deepest red) • Chlorine (chloros is Greek for pale green) • The Ytterby mine in Sweden • Yttrium • Erbium • Terbium • Ytterbium • Famous Scientists • Bohrium • Curium • Einsteinium
Compound • A compound is a unique form of matter in which two or more elements are chemically combined in fixed proportion by mass. • Law of Constant Composition and/or the Law of Definite Proportions: the elemental composition of a pure compound is always the same. • H2O (water), NaCl (salt), FeS (iron(II) sulfide), C4H10 (butane)
Pure Substances and Mixtures • Elements and compounds are examples of pure substances. • Combinations of elements and compounds result in mixtures. • Homogeneous mixtures • also called solutions • Heterogeneous mixtures
Homogeneous Mixtures (Solutions) • A mixture consisting of a single phase. • Properties • Uniform composition throughout • Components are indistinguishable • Can be separated by physical means • Air • Diet Dr. Pepper • Coffee
Distillation Allows a Solution to be Separated into its Components
Heterogeneous Mixtures • A mixture consisting of two or more phases. • A phase is a distinct region with its own physical properties. • Properties of heterogeneous mixtures • No uniform composition throughout • Components are distinguishable • Components can be separated by ordinary physical means • Club sandwich • Diet Dr. Pepper with ice • Salad dressing
MATTER Anything that occupies space and has mass Variable composition MIXTURES PURE SUBSTANCES Constant composition Physical separation COMPOUNDS ELEMENTS Chemical reactions HOMOGENEOUS MIXTURES HETEROGENEOUS MIXTURES Uniform throughout Two or more phases, each with its own set of properties
Properties of Matter • Physical properties can be observed without changing the chemical identity or composition of a substance. • Examples: color, density, boiling point, melting point, solubility, conductivity, ductility • Chemical properties describe reactions that substances undergo. • Examples: magnesium burns in oxygen to produce magnesium oxide.
Properties of Matter • Extensive properties are properties that depend on how much of the substance you have (sample size). • Examples: mass, volume • Intensive properties are independent of sample size. • Examples: boiling point, density.
Categorizing Properties of Matter temperature density color smell conductivity melting point boiling point mass volume heat of reaction (enthalpy) 2Mg + O2 2MgO flammability
Scientific Method A general approach to problem-solving, to understanding natural phenomena • Make observations (collect data). • Make a hypothesis (guess) as to what the underlying truth is. • Test the hypothesis by performing controlled experiments. • Repeat steps 1-3, modifying the hypothesis and the experiments until there is consistency. At this point, the hypothesis becomes a theory and eventually even a law.
The Scientific Method and Measured Data • Central to the scientific method is the accumulation and study of measured data. • A measurement consists of two parts: a number and a unit. • BOTH must be reported correctly! • A systematic way to report the number measured (by using the correct number of significant figures) communicates how good you think your measurements are. • A systematic set of units (SI units and the metric prefixes) allows scientists from different areas to communicate easily.
SI Base UnitsSI = Système International d’Unités *Memorize these units and their symbols.
Metric Multipliers *Memorize these units and their symbols.
SI Derived Units The seven SI base units may be used to derive any other SI unit. Two examples are: Volume = length (SI unit = meter) x width (SI unit = meter) x height (SI unit = meter) The SI unit for volume is the cubic meter (m3). Speed = distance (SI unit = meter) / time (SI unit = second) The SI unit for speed is meters/second (m/s).