Fundamentals of Chemistry Chem 1102 Aspects of Chemistry

Fundamentals of Chemistry Chem 1102 Aspects of Chemistry Fall 2008

Chemistry • The Central Science – The study of matter – Explains every aspect of daily life – Is essential to understand nearly all scientific, medical and pharmaceutical disciplines, and engineering • A Qualitative Science – Chemistry is based in experimental observation

Chemistry • A Quantitative Science – We want to know how many, how much, how good is the measurement • An Experimental Science • A Method of Inquiry – Based on the Scientific Method – An intellectual pursuit – To probe the world around us

Scientific Method • Identify a question • Propose a hypothesis • Construct and carry out experiment to test hypothesis • Observe and record results • Refine hypothesis • Test refined hypothesis with more expts (repeat as needed) • Develop theory that is consistent with observations and accepted laws of nature and predicts future exptal outcomes

Chemistry in Daily Life • Health care including diagnostics, treatment, medicine, prevention (p. 1, 17, 18, 78, 102, 113, 118, 128, 166, 172, 178, 208, 226) • Food (p. 2, 5, 7, 11, 13, 21, 29, 36, 52, 66, 83, 84, 100, 116, 118, 175, 197, 199, 205 • Environment (p. 46, 50, 105, 107, 122, 145, 180, 195) • Materials around the house (all the rest)

Chemistry • Chemistry is the study of matter – Matter has mass and volume – Matter has physical properties – Matter has chemical properties – There are 3 states of matter • And how matter changes – Life of the cell – Production and decay of material – Combustion of fuels

Figure 1. 16 Organization of Matter (Zumdahl)

Atomic Theory of Matter (1808) • John Dalton (1766 -1844) • Elements (matter) are composed of atoms • The atoms of a given element are identical. Each element is characterized by the mass of its atoms. • Compounds are formed when atoms of different elements combine with each other.

Atomic Theory of Matter (2) • A given compound is a chemical combination of the same atoms in the same relative numbers. • A chemical reaction is the rearrangement of atoms leading to new compounds. Atoms are neither destroyed nor created in a chemical reaction (Conservation of Mass).

• http: //www. rsc. org/chemsoc/timeline//page s/1911. html

A Deeper Look into the Atom Particle Mass (kg) Electron, e- 9. 11 E-31 Charg Discoverer e -1 J. J. Thomson Proton, p+ +1 E. Rutherford 0 Chadwick 1. 67 E-27 Neutron, n 0 1. 67 E-27 Other

Figure 2. 13 (Zumdahl) (a) Expected Results of the Metal Foil Experiment if Thomson's Model Were Correct (b) Actual Results

More on the Atom • An atom is uniquely defined by #p+ = Z = atomic number (see Periodic Table) • In a neutral atom, #p+ = #e-; note that #n is not equal to #p+ nor #e-. • In an atomic ion, #p+ ≠ #e- resulting in a net nonzero charge on the species – Neutral atoms can lose electrons producing a positive ion or cation because #p+ > #e– Or gain electrons - ion or anion because #p+ < #e-

Isotope • Atoms which have the same Z (same # p+) but a different A (different # n 0) • Most elements have isotopes that occur in nature in precise proportions (fractional abundances, %). • A few elements have no naturally occurring isotopes.

Figure 2. 21 The Periodic Table

Periodic Table • An arrangement of elements according to increasing atomic number (Z) which shows the periodic or regularly repeating nature of elemental properties. – Rows = periods – Columns = groups or families – Metals, Nonmetals, Semimetals – Main group (A), Transition Metals, Lanthanides and Actinides

• http: //www. webelements. com/ • http: //periodictable. com/ • http: //www. uky. edu/Projects/Chemcomics/

On to Molecules (n x 106) • Molecules form when atoms are connected by chemical bonds in which electrons act as the “glue” between atoms. • A compound has more than one type of atom bonded together.

Chemical Bond Types • IONIC: metal + nonmetal – Electrons are transferred from metal to nonmetal thus creating a cation (+) and anion (-) which attract each other • COVALENT: nonmetal + nonmetal – Electrons are shared by both atoms • METALLIC: metal + metal

Chemical Formula • Shorthand symbol for cmps • Qualitative description of the constituent elements in a molecule or ion. – C 12 H 22 O 11 contains C, H and O • Quantitative description of the relative numbers (subscripts) of atoms of each element. – One molecule of sucrose has 12 -C, 22 -H and 11 -O

Chemical Reaction • A chemical rxn is a rearrangement of atoms in which reactant compounds are converted into product compounds. • During a chem rxn, chemical bonds in the reactants are broken and chemical bonds in the products are created. • A rxn is accompanied by a change in energy (i. e. heat can be absorbed or given off), color, state of matter, etc.

Chemical Equation • Shorthand symbolic notation for a chemical reaction – CH 4(g) + O 2 (g) H 2 O(ℓ) + CO 2(g) – Note that this reaction is NOT BALANCED • Qualitative aspect – identity of reactants [R] and products [P]; use study of nomenclature to write equations – Identify the state of matter for each [R] and [P] – identify reaction type

Chemical Equation (2) • Quantitative aspect – how much reactant is consumed and how much product is formed – coefficients must be consistent with the Law of Conservation of Mass; atoms are neither created nor destroyed in a chemical reaction. – i. e. chemical equation must be balanced • CH 4(g) + 2 O 2 (g) 2 H 2 O(ℓ) + CO 2(g) Note that this reaction is BALANCED