Ch. 3 – Atoms: The Building Blocks of Matter

1. Ch. 3 – Atoms: The Building Blocks of Matter 3.1 – The Atom: From Philosophical Idea to Scientific Theory

2. Laws • Early investigation led to the discovery of 3 basic laws… • Law of conservation of mass – mass can’t be created or destroyed during ordinary chemical reactions or physical changes.

3. Laws • Law of definite proportions – chemical compounds contain the same elements in exactly the same proportions by mass regardless of the size of the sample or source of origin.

4. Laws • Law of multiple proportions – when elements combine, the ratio of masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers.

5. Helped to form… • Dalton’s Atomic Theory • All matter is composed of extremely small particles called atoms • Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties.

6. Atoms cannot be subdivided, created, or destroyed. • Atoms of different elements combine in simple whole number ratios to form chemical compounds. • In chemical reactions, atoms are combined, separated, or rearranged.

7. Dalton’s Atomic Theory • Parts are now invalid. • Is this still a theory? • Complete the section review on page 71 and do numbers 1-3 for tomorrow.