UNIT 2: Basic Chemistry

1. UNIT 2: Basic Chemistry BIG IDEA: Examining substances at the molecular level helps us understand basic processes of life

2. Basic Chemistry • Living and non living things are all made of the same basic building blocks of matter • Basic life processes all follow the laws of chemistry • Structure of Atoms • Chemical Reactions • Compounds and Mixtures • Water-Acids and Bases

3. Structure of Atoms Start big and end small OrganismsOrgan Systems  Organs  Tissues Cells  Compounds Elements Atoms

4. ATOM: Smallest amount of an element that still has the properties of that element. Atoms have structure and are made up of smaller particles that give them their characteristics and control their interactions with other atoms

5. Structure of an Atom e N P Nucleus: Center of atom, where protons and neutrons are located P N e

6. Structure of an Atom e Orbit: Area outside nucleus where electrons are in constant motion N P P N e

7. e N P P N e Structure of an Atom Orbits spin and rotate in three dimensions.

8. e N P P N e Structure of an Atom Each Orbit is a specified distance from the nucleus.

10. e e e e e Orbit e N P Nucleus P N e e e e e Structure of an Atom

11. Structure of an Atom

12. Structure of an Atom An element has its own number of e, P and N - e N + P + P N - - e

13. Structure of an Atom The different combination of P, N and e make each element unique - e N + P + P N - - e

14. Main Elements in Human Body • Oxygen • Carbon • Hydrogen • Nitrogen

15. Main Elements in Earth’s crust • Oxygen • Silicon • Aluminum • Iron

16. Structure of an Atom Atomic particles: - Protons, P+, Charge of +1 - Electrons, e-, charge of -1 - Neutrons, N, zero charge

17. Structure of an Atom Normally, all the “+” of the protons and the “-” from the electrons balance out and the overall charge of an atom is zero.

18. - e Structure of an Atom What if an atom loses an electron? - e e N N + P P + P P N N - Atom becomes positive -

19. - e Structure of an Atom What if an atom gains an electron? - e N + P + P N - Atom becomes negative - - e

20. Structure of an Atom Any charged atom is called an ion - Positive ions are called cations - Negative ions are called anions

21. Structure of an Atom-The Periodic Chart Atomic number is the number of protons Atomic Mass is the “approximate” number of protons + neutrons Assume Electrons = Protons (except Ions)

22. Atomic Mass = Protons + Neutrons Why don’t the electrons figure in?

23. Drawing Atoms: • Each orbit can hold a maximum number of electrons. • - Orbit 1: holds a max of 2 • - Orbit 2: holds a max of 8 • - Orbit 3: holds a max of 8 • You must fill the inner orbits before adding electrons to the outer orbits. • Electrons in the outermost orbit are called valence electrons

24. e e e e e N e P P N P N N P N N N P P P e P N N N P N P P e P N e e e e Examples 12 Mg 24

25. Examples 8 O 16

26. Examples 10 Ne 20

27. Examples • Look at the column on periodic table to figure out Valence electrons • C __________ N____________

28. Examples • Look at the column on periodic table to figure out Valence electrons • O __________ H ____________

29. Chemical Reactions- Bonds • Compounds • Atoms are chemically bound together • Definite proportions required • Properties of a compound are different from the properties of the elements that make up that compound • Made up of many particles of the same type held together by a bond using the valence electrons

30. Types of bonds that form Compounds • Covalent- each atom shares electrons with the other • Molecules are formed by this type of bond

31. Types of bonds that form Compounds • Ionic Bond- One atom gives an electron to the other

32. IONIC: • Creates opposite charge that holds atoms together • Form crystals

33. Chemical Formulas • Al2O3 • 2Al2O3 Subscript shows how many atoms of the elementit is written after This number shows how many of the entire molecule their are

34. Chemical Reactions • Change in the arrangement of atoms that creates a different substanceNumber of atoms before and after the reaction are equal. A + B  C synthesis reaction A  B + C decomposition A + B  C + D Displacement

35. Chemical Reactions • Reactants: The “stuff” you start with • Products: The “stuff” you end up with A + B  C Reactants Products

36. Chemical Reactions C6H12 O6+ 6O26CO2+ 6H2O C6H12 O6 + C6H12 O6 C12H22O11 + 6H2O H20  H+ + OH-

37. Mixtures • Mixtures have “ingredients” that do not bind chemically with each other • Each ingredient keeps its own properties • Definite proportions not required • Types: solution, suspension, colloid

38. Mixtures • Solution: homogeneous; even throughout; solute (substance) completely dissolves in solvent (liquid) examples: air, • Suspension: Heterogeneous; looks even if shaken; but particles settle to bottom examples-water column in oceans and lakes

39. Mixtures • Colloid: heterogeneous BUT does not settle; sort of in between the other two. Examples-milk and fog

40. Mixtures vs. Compounds Look at your notes: What are three big differences between Mixtures and Compounds?

41. Properties of Water Water is held together with special covalent bond called polar covalent bond - Means water has poles, or ends. - O is the negative end - H’s are the positive end

42. Water is the Universal Solvent • Important solvent in many solutions • Anything with a charge will attract water molecules and dissolve • Ionic and polar molecules have charge • Nonpolar molecules (like fat) do not have charge and will not dissolve

43. Properties of Water

44. Properties of Water Cohesion: Water molecules stick together because of charges

45. Cohesion Creates Surface tension - allows stickbugs to walk on water!

46. Adhesion Water molecules stick to other charged substances like glass Glass stirring rod

47. Concept of pH • pH = power of Hydrogen • A way of measuring how many Hydrogen ions, H+, there are in a solution • Determines whether a solution is an acid or a base

48. Acids and Bases • Acids: a chemical that when dissolved in water releases a hydrogen ion (H+) HX (in water)  H+ + X-

49. Properties of Acids • Taste sour – think of lemon • Turn litmus paper from blue to red • Corrodes Metal • Examples: Sulfuric Acid, Lemon Juice, Battery Acid

50. Acids and Bases • Base: a chemical that when dissolved in water releases a hydroxide ion (OH-) XOH (in water)  OH- + X+