* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download (3.3 × 10!4) + (2.52 × 10!2) = (3.3 × 10!4) × (2.52 × 10!2)
Electrolysis of water wikipedia , lookup
Chemical element wikipedia , lookup
Rutherford backscattering spectrometry wikipedia , lookup
Water splitting wikipedia , lookup
Molecular Hamiltonian wikipedia , lookup
Periodic table wikipedia , lookup
Freshwater environmental quality parameters wikipedia , lookup
Condensed matter physics wikipedia , lookup
Al-Shifa pharmaceutical factory wikipedia , lookup
Biochemistry wikipedia , lookup
Stoichiometry wikipedia , lookup
Size-exclusion chromatography wikipedia , lookup
Chemical weapon proliferation wikipedia , lookup
California Green Chemistry Initiative wikipedia , lookup
Chemical weapon wikipedia , lookup
Gas chromatography–mass spectrometry wikipedia , lookup
Chemical plant wikipedia , lookup
Chemical industry wikipedia , lookup
Chemical Corps wikipedia , lookup
X-ray photoelectron spectroscopy wikipedia , lookup
Spinodal decomposition wikipedia , lookup
History of molecular theory wikipedia , lookup
Transition state theory wikipedia , lookup
Chemistry: A Volatile History wikipedia , lookup
Registration, Evaluation, Authorisation and Restriction of Chemicals wikipedia , lookup
Organic chemistry wikipedia , lookup
Inorganic chemistry wikipedia , lookup
IUPAC nomenclature of inorganic chemistry 2005 wikipedia , lookup
Chemical potential wikipedia , lookup
Safety data sheet wikipedia , lookup
Computational chemistry wikipedia , lookup
Atomic theory wikipedia , lookup
Drug discovery wikipedia , lookup
Physical organic chemistry wikipedia , lookup
VX (nerve agent) wikipedia , lookup
History of chemistry wikipedia , lookup
CHAPTER 1 Basic Concepts of Chemistry Chapter Outline 1-1 1-2 1-3 1-4 1-5 1-6 1-7 1-8 Chemistry and Its Methods Sustainability and Green Chemistry Classifying Matter Elements Compounds Physical Properties Physical and Chemical Changes Energy: Some Basic Principles Chemistry is the study of Matter Matter Anything that occupies space and has mass. Mass Measure of the amount of matter that an object contains. Chemistry and Its Methods Hypothesis: A tentative explanation or prediction based on experimental observations. Law: A concise verbal or mathematical statement of a behavior or a relation that seems always to be the same under the same conditions. Theory: a well-tested, unifying principle that explains a body of facts and the laws based on them. It is capable of suggesting new hypotheses that can be tested experimentally. Qualitative Observations No numbers involved Color, appearance, statements like “large” or “small Stating that something is hot or cold without specifying a temperature. Identifying something by smell No measurements Quantitative Observations A quantity or attribute that is measureable is specified. Numbers with units are expressed from measurements. Dimensions are given such as mass, time, distance, volume, density, temperature, color specified as a wavelength etc... Goals of Science Predict Control Understanding Explaining Dilemmas and Integrity in Science Experimental results should be reproducible. Furthermore, these results should be reported in the scientific literature in sufficient detail that they can be used or reproduced by others. Conclusions should be reasonable and unbiased. Credit should be given where it is due. Sustainability and Green Chemistry Prevent waste Synthetic methods should maximize materials Chemical synthesis should reduce toxicity Energy requirements should be minimized Raw materials should be renewable and practical Chemical products should not persist in the environment Substances should be chosen to minimize risks Classification of Matter Classify according to its physical state Gas Liquid Solid Classify according to its composition Element Compound Mixture Classifying Matter: State of Matter States of Matter Solid – Liquid – Definite Shape Definite Volume Lowest Kinetic Energy Indefinite Shape Definite Volume Intermediate Kinetic Energy Gas – Indefinite Shape Indefinite Volume Highest Kinetic Energy Classifying Matter Mixtures: Homogenous and Heterogeneous A homogeneous mixture consists of two or more substances in the same phase. No amount of optical magnification will reveal a homogeneous mixture to have different properties in different regions. A heterogeneous mixture does not have uniform composition. Its components are easily visually distinguishable. When separated, the components of both types of mixtures yields pure substances. Mixtures Heterogeneous Mixtures can be separated by filtration. Mixtures A combination of two or more pure substances. Homogeneous - Uniform composition Heterogeneous - Non-uniform composition Physical Properties Mixtures may be separated by physical properties: Physical Property Means of Separation Density Decantation, centrifugation Boiling point Distillation State of Matter Filtration Intermolecular Forces Chromatography Vapor pressure Evaporation Magnetism Magnets Solubility Filtration Are these heterogeneous or homogenous? Blood Urine “T-Bone” steak Gasoline Twinkie Colt 45 Pure Substances A pure substance has well defined physical and chemical properties. Pure substances can be classified as elements or compounds. Compounds can be further reduced into two or more elements. Elements consist of only one type of atom. They cannot be decomposed or further simplified by ordinary means. Pure Substances Element Cannot be converted to a simpler form by a chemical reaction. Example: sodium and helium Compound Combination of two or more elements in a definite, reproducible way. Example: water - H2O Elements • • • The elements are recorded on the PERIODIC TABLE. There are 117 recorded elements at this time. The Periodic Table will be discussed further in Chapter 2. Chemical Compounds Chemical compounds are composed of two or more atom. Chemical Compounds All Compounds are made up of molecules or ions. A molecule is the smallest unit of a compound that retains its chemical characteristics. Ionic compounds are described by a “formula unit”. Molecules are described by a “molecular formula”. Chemical Compounds Physical Properties Characteristics that can be evaluated without changing the composition of the material Color Odor Density Melting point Thermal conductivity Volume Hardness Physical Properties Some physical properties: − Color − State (s, g or liq) − Melting and Boiling point − Density (mass/unit volume) Extensive properties (mass) depend upon the amount of substance. Intensive properties (density) do not. Physical Properties Physical properties are a function of intermolecular forces. H Water (18 g/mol) liquid at 25oC Methane (16 g/mol) gas at 25oC H C H H O H • Water molecules are attracted to one another by “hydrogen bonds”. (Chapter 11) • Methane molecules only exhibit week “London Forces”. (Chapter 11) H Physical Properties Physical properties are affected by temperature (molecular motion). The density of water is seen to change with temperature. Chemical Properties Results in a change in the composition of a material. Explains how one substance acts in the presence of another. Chemical Reaction - how the change occurs. A chemical property of wood is it’s ability to burn - combustion. Reactants Products Wood + O2 CO2 + water + heat The reactants and products are very different. Chemical Properties Chemical properties are really chemical changes. The chemical properties of elements and compounds are related to periodic trends and molecular structure. A Scientific Model Models are commonly used to help visualize atoms and molecules. Atom The smallest unit of an element that has all of the properties of an element. Molecule The smallest unit of a pure substance that has all of the properties of that substance. It may contain more than one atom and more than one element. Molecular Formula A molecule is the smallest unit of a compound that retains the chemical characteristics of the compound. Composition of molecules is given by a molecular formula. Physical Change A change that does not entail any change in chemical composition Solid iron (Fe) melting in a blast furnace Fe(s) → Fe(l) Ice cube melting H2O(s) → H2O(l) Chemical Change Involves a change in chemical composition Results in a change in composition or structure Iron metal reacts with oxygen to form rust (iron oxide) 4Fe + 3O2 2 Fe2O3 H2 and O2 react to form Water 2H2 + O2 2 H2O Chemical vs. physical change Chromatography separated components of mixture didn’t change the components Electrolysis water was changed to hydrogen and oxygen Which are chemical or physical changes? Mulching leaves Milk turning sour Odor of Mothballs Ice melting Beer going flat Energy: Some Basic Principles Energy can be classified as Kinetic or Potential. Kinetic energy is energy associated with motion such as: • The motion at the particulate level (thermal energy). • The motion of macroscopic objects like a thrown baseball, falling water. The movement of electrons in a conductor (electrical energy). Wave motion, transverse (water) and compression (acoustic). Matter consists of atoms and molecules in motion. Energy: Some Basic Principles Potential energy results from an object’s position: Gravitational: An object held at a height, waterfalls, etc. Energy stored in an extended spring. Energy stored in molecules (chemical energy, food) The energy associated with charged or partially charged particles (electrostatic energy) Nuclear energy (fission, fusion).