Chemistry 102 Dr. Don DeCoste 367J Noyes Lab decoste@illinois.edu 3-4 pm Tuesdays and Thursdays By appointment; open door policy http://chem.illinois.edu

Office Hours No office hours Tuesday, January 26. Please email me if you’d like to meet with me.

To Do Chapters 1 and 2: read and text homework. Lon-Capa assignments #1 and #2. For Tuesday: start reading Chapter 3 and doing the text homework.

Clicker Question Which best describes your current status? a) Freshman (1st year) b) Sophomore c) Junior d) Senior e) 5th-year senior

Clicker Question Which best describes your major? a) Chemistry or Chemical Engineering b) Biology or Life Science c) Engineering d) Agriculture e) Other

Clicker Question When was your last chemistry class? a) I took Chemistry 101 last semester. b) I took Chemistry 101 a few semesters ago. c) I am retaking Chemistry 102. d) I haven’t had chemistry since high school. e) I have never taken chemistry before.

Uncertainty in Measurement

What is the volume reading of the buret? Three good answers: 20.15 mL 20.16 mL 20.17 mL 20.16 ± 0.01 mL

Clicker Question How many significant figures are in the measurement 0.030140 liters? a) 3 b) 4 c) 5 d) 6 e) 7

Clicker Question You add 82.4 mL of water in a graduated cylinder to 25 mL of water in a beaker. How much water should you report? a) 100 mL (1 significant figure) b) 110 mL (2 significant figures) c) 110. mL (3 significant figures) d) 107 mL (3 significant figures) e) 107.4 (4 significant figures)

Clicker Question In the last problem you added 82.4 mL and 25 mL to get an answer reported to 3 significant figures. What is the final reported answer if you multiply 82.4 cm and 25 cm? a) 2000 cm2 (1 significant figure) b) 2100 cm2 (2 significant figures) c) 2060 cm2 (3 significant figures) d) 2.10 x 103 cm2 (3 significant figures) e) 2060. cm2 (4 significant figures)

Particulate Nature of Matter Atom: smallest part of an element that is still that element (fundamental unit of which elements are composed). Molecule: Two or more atoms joined and acting as a unit. (element or compound)

Atomic Element

Molecular Elements

Compounds

Macroscopic versus Microscopic

Chemistry – A Big Idea Atoms have structure. Subatomic particles – electrons, protons, and neutrons. Atoms are mostly open space. Atoms can attract (and repel) one another.

Atomic Structure–So What? Bonds form within molecules. Molecules are sticky (forces between molecules). Different reactivities of elements (why is He in Mylar balloons?). Fireworks. Pools close during a thunderstorm.

Using The Periodic Table Symbol, name, number of protons (all of these are related). Number of electrons in a neutral atom or in ion. Charges for common ions. Metals and non-metals. Formulas of some ionic compounds. Naming simple compounds.