Fundamentals of Chemistry

Chem 1102 Aspects of ChemistryFall 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//pages/1911.html

A Deeper Look into the AtomParticle Mass (kg) Charg

eDiscoverer

Electron, e- 9.11E-31 -1 J.J. Thomson

Proton, p+ 1.67E-27 +1 E. Rutherford

Neutron, n0 1.67E-27 0 Chadwick

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 # n0)

• 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.– C12H22O11 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– CH4(g) + O2 (g) H2O(ℓ) + CO2(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• CH4(g) + 2O2 (g) 2H2O(ℓ) + CO2(g)

Note that this reaction is BALANCED