Chapter 2

1. Chapter 2 The Chemistry of Life

2. You should know: • What three subatomic particles make up atoms? • How are all the isotopes of an element similar? • What are the two types of chemical bonds?

3. The Big Idea:Matter and Energy • Life depends on chemistry • Chemistry = • Matter = • Chemical reactions keep you alive

4. Atom…way smaller than a cell • Basic unit of matter • The building blocks of EVERYTHING! • Your phone, a dog, your lunch, your body, your bed, your clothes, your car, your house, your pencil!

5. Democritus, 2500 years ago • Democritus asked, can you divide a substance without limit, or does there come a point at which you cannot divide the substance without changing it into something else? • Democritus thought that there had to be a limit, and he called the smallest fragment the atom, from the Greek word atomos, which means “unable to be cut.”

6. Subatomic particles • P • N • E Protons Electrons Neutrons

7. Element Mercury, Hg • = • Elements make up earth & organisms • cannot be broken down by a chemical process into a simpler substance • 100+ elements are known, but only about two dozen are commonly found in living organisms. • Ex: Oxygen (O), Nitrogen (N), Carbon (C) Phosphorus (P), Hydrogen (H)

9. Atomic number 6 C Carbon 12.011

10. Nonradioactive carbon-12 Nonradioactive carbon-13 Radioactive carbon-14 6 electrons 6 protons 6 neutrons 6 electrons 6 protons 7 neutrons 6 electrons 6 protons 8 neutrons Isotope

11. Isotopes • mass number = • Isotopes are identified by their mass numbers; for example, carbon-12, carbon-13, and carbon-14.

12. 6 C Carbon Atomic Mass 12.011 • The average of the masses of all of an elements isotopes is called its atomic mass http://ed.ted.com/lessons/just-how-small-is-an-atom

13. Isotopes • Because they have the same number of electrons, all isotopes of an element have the same chemical properties. • Isotopes - have an unstable nucleus that breaks apart giving off energy in the form of radiation

14. Radioactive isotopes • Can be dangerous • Can be used practically • Radioactive dating • Treat cancer • Kill bacteria • used to tell age of fossils • preserve food

15. Compounds • = • Often has very different physical and chemical properties than its elements. • Ex) H2O, 2 H and 1 O, 2:1 ratio • Ex) NaCl, 1Na and 1Cl, 1:1 ratio

19. Table Salt

20. Chemical Bonds • The force that holds atoms together • Electrons are the key players • valence electrons = 2 main types of bonds • Ionic bonds • Covalent bonds

21. Ionic Bonds

22. Sodium atom (Na) Chlorine atom (Cl) Sodium ion (Na+) Chloride ion (Cl-) Transfer of electron Protons +11 Electrons -11 Charge 0 Protons +17 Electrons -17 Charge 0 Protons +11 Electrons -10 Charge +1 Protons +17 Electrons -18 Charge -1

23. If an atom loses an electron it becomes ______________ • called a • If an atom gains an electron it becomes _______________ • called a

24. Covalent Bonds • Sometimes electrons are shared by atoms instead of being transferred. • The moving electrons travel about the nuclei of both atoms, forming a covalent bond.

25. Covalent Bonds • The structure that results when two or more atoms are joined together by covalent bonds is called a molecule, the smallest unit of most compounds. • Ex: Each hydrogen atom is joined to water’s lone oxygen atom by a single covalent bond. Each hydrogen atom shares two electrons with the oxygen atom.

26. COVALENT VS. IONIC

27. Van der Waals Forces • A slight attraction that develops between the oppositely charged regions of nearby molecules due to unequal sharing of electrons

30. Describe the structure of an atom. • Why do all isotopes of an element have the same chemical properties

31. 3. What is a covalent bond? 4. What is a compound? How are they related to molecules

32. 5. How are ionic bonds and Van der Waals forces similar? How are they different?