Introduction to the Atom

Objective: Draw conclusions about something unknown by inference* and indirect observations… * Deduction; supposition; assumption

Drawing Conclusions by Indirect Observation 1.Think about the four “mystery” cans that you handled. 2.What do you think was inside each one? 3.Do you know for sure what was inside? 4.Which of your five senses were you able to use? 5.What other ways of testing could you use, WITHOUT opening the can? This type of investigation is called INDIRECT OBSERVATION, because you cannot directly see the object; you must “infer” its properties using other means.

Container 1: Sand Container 2: Nails (3) Container 3: One marble Container 4: Small wood cylinder

Objectives 1.Understand the basic concept of the atom 2.Understand, identify & explain the concept and applications of… Law Conversation of Mass Dalton’s Theory

The Atom Smallest unit of matter that retains the properties of its respective element. Democritus (Greece, 400 B.C.) called the basic particle of matter the “atom” (indivisible).

Law of Conservation of Mass Chemical reactions and physical changes do not change a system’s mass.

Law of Definite Proportions A given compound will always have the same mass proportions of each of its components.

Dalton’s Theory 1.All matter is composed of atoms. 2.All atoms of a given element are identical in size, mass and other properties. 3. Atoms of different elements differ from each other in size, mass, etc. John Dalton, England, 1766 – 1844, Mathematician, Physicist, Chemist

Dalton’s Theory, cont’d. 4. Atoms cannot be subdivided, created or destroyed. (Note: This was later disproven.) 5. Compounds are made of a combination of simple ratios of atoms. 6. Chemical reactions are the combination, rearrangement or separation of atoms.

Dalton’s Theory, cont’d. Chemical reactions consist of the combination, separation or rearrangement of atoms; during these processes the atoms are not subdivided, created or destroyed. This helps provide an explanation for the Law of Conservation of Mass.

A Year in the “Life” of a Carbon Atom Limestone Extraction (mining) Lime production Plant emission See p. 68

A Year in the “Life” of a Carbon Atom Respiration Dissolution Evaporation Assimilation Metabolism See p. 68

A Year in the “Life” of a Carbon Atom Limestone – Calcium carbonate, CaCO 3 “Lime” production – Lime + Carbon dioxide, CaO + CO 2 Plant emission = CO 2 (In what phase is this compound?) Respiration - CO 2 not taken into bird’s bloodstream (Why?) Dissolution: CO 2 dissolved in rain water, falls into ocean CO 2 + H 2 O  H 2 CO 3 (Carbonic acid) cont’d. 

A Year in the “Life” of a Carbon Atom Evaporation: CO 2 evaporates back into atmosphere Assimilation: CO 2 is taken into the plant where it contributes to the formation of glucose, an compound essential to life (metabolism): C 6 H 12 O 6 - Glucose, a type of sugar (What are sugars used for in the body?) 1.What conclusions can you draw from this sequence of events? 2.What other examples of elements interacting in nature can you think of?