1. CHAPTER 3 ATOMIC STRUCTURE
3.1 Defining the Atom
Why can you see this?

2. Chapter 3 Atomic Structure
Can you still see it?
NO?
Of course not, it’s been reduced to the size of an atom.
An atom is the smallest particle of an element that retains its identity in a chemical reaction.

3. Continuing section 3.1 Democritus
He was a Greek philosopher (460BC – 370 BC) that was the first to suggest that all things were made up of small indivisible and indestructible particles, he called atoms.
He had no scientific support, so what makes him right?

4. 3 Basic Laws of Chemistry
1. Law of conservation of mass:
Matter can neither be created nor destroyed by ordinary chemical reactions.
Mg + HCl H2(g) + MgCl2
2. law of definite proportions:
Chemical compounds contain the same elements in exactly the same proportions by mass regardless of the size or source of the sample

5. 3 Laws cont.
3. Law of multiple proportions: if two or more different compounds are composed of the same two elements, then the ratios of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers.
In CO g of O combine with 1 g C
In CO g of O combine with 1 g of C
Both ratio of masses 1.33g and 2.66g are a 2 to 1 ratio

6. Continuing section 3.1 John Dalton’s Atomic theory
2000 yrs after Democritus, Dalton established his atomic theory.
Using science he transformed Democritus ideas into a scientific theory.
Dalton studied the ratios in which elements combine in chemical reactions.

7. Continuing section 3.1 Dalton Atomic Theory
1. all elements are composed of tiny indivisible particles called atoms.
2. atoms of the same element are identical. Atoms of one element are different from another element.
3. Atoms of different elements can physically mix together (chemically combine) in whole-number ratios to form compounds.

8. Continuing section 3.1
4. Chemical reactions occur when atoms are separated, joined, or rearranged. Atoms of one element are never changed into another element from a chemical reaction.

9. Fun Info
Atoms are so small that if you lined up 100,000,000 atoms of copper (Cu) it would only make a line about 1 cm long.
Copper atoms Silicon Atoms
Electron tunneling microscope images

10. FermiLab, Chicago 17 mile circumference

12. Particle collisions