Objective: List and explain the 3 laws of atomic theory 5 principles of Dalton’s atomic theory.Catalyst 10/28/101. 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°C B.18°C C.23°C D.28°C
1st, 2nd and 7th • Test Reflection (10) • Test Revisions/Study Time (30) • Homework: Test revisions, due Monday
4th and 5th • Test Reflection (10) • Atomic Theory Notes (25) • Homework: Page 78, questions 1-6 in the book
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.
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.
Law of definite proportions • A given compound is made of the same elements in the same ratio every time • E.g.; Water is always H2O; 2 Hydrogen atoms for every 1 Oxygen atom • Not
Law of Conservation of Mass • Mass of products must equal the mass of reactants
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.
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.
Dalton’s atomic theory • 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.
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.
Atoms to Elements • What makes elements different from one another? • The number of protons! Also called the atomic number.