1. The Chemistry of Life Life is, even at the smallest level, an extremely sophisticated form of CHEMISTRY.

2. Matter – anything that takes up space and has mass. Matter is made of smaller particles called atoms.

3. What are atoms? Atoms: the basic unit of matter All matter or things that have mass and occupy space are made of atoms Incredibly small (100 million side by side are about the size of you pinky nail)

4. The Nature of Matter At the tiniest level, all matter is made up of three subatomic parts A. proton B. electron C. neutron Subatomic: small bits of matter that make up an atom

5. Structure of an Atom A. Protons- positively charged particles found in the nucleus, Protons have an atomic mass of 1. Don’t confuse nucleus with the nucleus of a cell. Nucleus means centrally located or essential part.

6. B. Neutrons- particles with no charge found in nucleus atomic mass of 1

7. C. Electrons- negatively charged particles Found outside or surrounding nucleus They are so light, they are said to have no atomic mass.

9. Elements Element: substance in its simplest form, and cannot be broken down any further. All elements are made of ONE type of atom. For example: Carbon is made up of only carbon atoms.

10. Elements are represented by a symbol on the periodic table (1 or 2 letters): –Carbon: C –Hydrogen: H –Sodium: Na

11. 4 elements make up 96% of all living matter from trees to bacteria to humans: Carbon, Hydrogen, Oxygen and Nitrogen. Remember CHON

12. Periodic Table: Arrangement of elements based on their chemical properties and atomic numbers The order of elements on the periodic table is based on their atomic number. Atomic number: total number of protons in the nucleus of an atom.

14. Carbon has an atomic number of 6 so it has 6 protons in the nucleus.

15. The number of protons equals the number of electrons. In order for the atom to be stable, the number of protons (+charge) must equal the electrons (- charge ) Carbon has six protons so it also has six electrons.

16. Mass Number (atomic weight): total number of protons plus the number of neutrons. Mass number can also be called the atomic mass or mass weight. How can you figure out the number of neutrons ?

17. Neutrons = mass number – atomic number Carbon has 6 neutrons (12 – 6 = 6)

18. 6 C Carbon 12.011 Section 2-1 An Element in the Periodic Table Go to Section: Atomic number: number of protons in the nucleus. Also equals the number of electrons outside the nucleus Mass number: number of protons plus the number of neutrons.

19. Chemical Compounds Compounds: substances formed by the chemical combination of 2 or more elements. Water is a compound H 2 O - water is formed by the three elements. Two hydrogen, one oxygen.

20. Other examples of compounds –NaCl -Sodium chloride or table salt is formed from two elements, on sodium (Na) and one Chlorine (Cl) –C 6 H 12 O 6 : glucose is formed by combining 24 elements; six carbon, 12 hydrogen, and six oxygen.

21. Compounds are connected together by bonds. chemical bond is an attraction between atoms that allows the formation of compounds.

22. There are many different types of bonds. 1.Covalent bond 2. Ionic bond 3. Polar covalent bond 4. Hydrogen bond We talk about four here. More later.

23. 1. Covalent bond: atoms share one or more pairs of electrons. Each atom donates half of the electrons to be shared –Forms compounds

24. H 2 O: water is formed by two single covalent bonds There is one bond between one o 1 2

25. 2. Ionic bonds: bonding from the attraction between two atoms with opposite charges. Sodium (Na+) has a positive charge Chlorine (Cl-)has a negative charge The positive is attracted to the negative and sodium chloride or salt is formed.

26. Water The water molecule is said to be polar covalent 3. Polar covalent: uneven sharing of electrons In water, there is an uneven sharing of electron between the H and O

27. O has more protons (+) than H therefore O has a greater pull on the electrons (-) than H, leaves H with a slightly positive charge and O with a slightly negative charge The result is a polar molecule, like a weak magnet

28. Water has two polar covalent bonds

29. 4. Hydrogen Bonds are formed when the attraction between the H atom on 1 molecule (+) is attracted to another atom that has a slightly negative charge Occurs in water due to the polar covalent bonds giving the water a positive charge on one side and negative on the other.

30. Hydrogen bonding of water

31. Hydrogen Bonding explains the properties of water – cohesion and adhesion We will see this in the penny lab.

32. Cohesion – attraction between molecules of the same substance. Water molecules have a positive and negative side. Causes the to be attracted and stick to each other. Forms a bubble on the penny.

33. Adhesion – attraction between molecules of different substances. –Ex) “cupping” of water on edge of graduated cylinder Water is attracted to the glass on the cylinder.

34. All life is affected by pH. pH is how we measure the level of acids and bases. Ex: fish tanks, swimming pools. pH- the measurement of the concentration of hydrogen ions in solution. The more H+ that a chemical releases, the more dangerous or reactive it is.

35. The pH scale goes from 0 to 14 Acids have a pH from 0 to 6.9 pH 7= neutral (distilled water) Bases (AKA alkaline) have a pH from 7.1 to 14

36. Acid – solution that has excess Hydrogen ions (H+) HCl -------  H+ + Cl- Base – solution that has excess hydroxide ions (OH-). NaOH --------  Na+ + OH-

37. Section 2-2 pH Scale Go to Section: pH Scale

38. Neutralization Reactions: An acid and base react to become neutral The product is always salt and water. Example: HCl + NaOH ------> NaCl + H 2 0