1. Objective: List and explain the 3 laws of atomic theory 5 principles of Dalton’s atomic theory. Catalyst 10/28/10 1. In general, the results of Study 1 suggest that peony seeds that are placed in a petri dish containing damp paper are most likely to germinate when they are maintained at which of the following temperatures? Explain. A.13°CB.18°CC.23°CD.28°C.

2. 1 st, 2 nd and 7th Test Reflection (10) Test Revisions/Study Time (30) Homework: Test revisions, due Monday

3. 4 th and 5th Test Reflection (10) Atomic Theory Notes (25) Homework: Page 78, questions 1-6 in the book

4. Atomic Theory Atomic theory states that atoms are the building blocks of all matter –Atoms are incredibly small! –What we know about them is based on indirect evidence.

5. History of atomic theory 500 BC Democritus proposed idea of atom- but he had no experimental data to support it. 1800 Dalton proposed an atomic theory supported by experimental data.

6. Law of definite proportions A given compound is made of the same elements in the same ratio every time –E.g.; Water is always H 2 O; 2 Hydrogen atoms for every 1 Oxygen atom Not

7. Law of Conservation of Mass Mass of products must equal the mass of reactants

8. Law of Multiple Proportions When the same elements combine to form different compounds, comparing the ratios of the masses of each type of matter gives a simple ratio.

9. Dalton’s Atomic theory Support for his theory came when he began looking at the masses of elements that combined with each other. He found that elements combine in simple ratios by mass.

10. Dalton’s atomic theory –all matter is composed of tiny, indivisible particles called atoms. –All atoms of the same element are identical in properties –Atoms of different elements differ in properties. –Atoms can neither be created nor destroyed. –Atoms of two or more different elements can combine in small whole number ratios to form compounds.

11. Dalton’s atomic theory 2 problems with his theory: –Atoms of the same element can have different masses –atoms have subatomic particles (electrons, protons and neutrons) So Dalton’s theory is not completely correct.

12. Atoms to Elements What makes elements different from one another? –The number of protons! Also called the atomic number.