The Chemistry of Life

Atoms and Their Interactions We will start by looking at the elements…

Elements are made up of particles called atoms An atom is the smallest particle of an element that has the characteristics of that element.

Protons Neutrons electons 1. Name the 3 subatomic particle, their location within an atom, and their charge Protons Neutrons electons

Protons, p+ +1 charge Very small Found in the nucleus # of p+ in an atom determines what it is Proton

Neutrons, no Have no charge Same mass as a proton Very small Also found in the nucleus Neutrons

Electrons, e- Outside of the nucleus are the electrons, e-: -1 charge Even smaller that p+ and no Located very far away from the nucleus in a region called the orbitals or energy levels There is a lot of space between the nucleus and electrons

Parts of the Atom From the inside to the outside: The center of the atom is the nucleus The nucleus contains Protons Neutrons

a. give the # of p, n, e b. example: atomic #9 Atomic Mass = 19 2. When given the atomic #, atomic mass, or symbol for an atom, be able to: a. give the # of p, n, e b. example: atomic #9 Atomic Mass = 19 # of protons = 9 # of Neutrons = 10 # of electrons = 9 Symbol = F (fluorine)

The Periodic Table (Pages 36 & 37 of your book) 1 Atomic Number H Element Symbol Element Name Hydrogen Mass Number or Atomic 1.0079

Periodic Table Lab Activity Put lab into your table of contents. Get started finding all elements listed.

On Earth, 90 elements occur naturally Element - subst. that can’t be broken down into simpler chemical substances Represented by a symbol Ex.) C represents Carbon, Ca represents Calcium On Earth, 90 elements occur naturally Only about 25 are essential to living organisms Four elements make up more than 96% of the human body Hydrogen, Oxygen, Nitrogen, & Carbon

So where do all these parts of an Atom Go??

3. If an atom has 12 electrons, how many are in it’s outer level? Find element 12 on periodic table:

4. How many electrons, maximum, can fit into the 1st, 2nd, and 3rd energy levels of an atom?

The K-shell Can hold 2 electrons Hydrogen (1 proton, 1 electron) Helium (2 protons, 2 electrons)

The L-shell Can hold 8 electrons                                    Lithium                                    Beryllium                                    Boron                                    Carbon                                    Nitrogen                                    Oxygen                                    Fluorine                                    Neon

The M-shell Can hold 8 electrons Potassium Calcium

An element is stable when it has a full outer shell of electrons. 5. Determine if an atom is stable, based on how many electrons are in its outer level. An element is stable when it has a full outer shell of electrons. It must have a shell of 2 then 8 electrons. An element with a full outer shell (8) will be stable and act like its nearest noble gas.

Atomic Structure Practice Now practice drawing the following Atomic Structures: Make sure to cut out and tape into lab book.

- Compounds and Bonds notes 6. If an atom has 8 electrons, how many covalent bonds will it likely form? 7. Describe the behavior of electrons in a covalent, polar covalent and ionic bond. - Compounds and Bonds notes

Compounds & Bonding A Compound is a substance composed of 2 or more elements bonded together Ionic Bond - attractive force between 2 ions of opposite charges (“opposites attract”) Covalent Bond - 2 atoms share electrons More abundant in living things!!

8. If an atom gains 2 electrons, what is it’s charge. 9 8. If an atom gains 2 electrons, what is it’s charge? 9. If an atom loses 1 electron, what is it’s charge?

10. If two atoms are isotopes, what is the difference between them? If the # of e- changes, then it is called an ion If the # of no changes, then the atom is called an isotope

Atomic Structure and Bonds STOP Atomic Structure and Bonds Activity sheet handout

11. What are the 6 most common elements found in living things? Oxygen (O) Carbon (C) Hydrogen (H) Nitrogen (N) Phosphorus (P) Sulfur (S)

12. What are trace elements and give an example of why they are important. Elements that make up less than 0.01 percent of your body mass, but are critical to your health. Example: You need about 0.15mg of the trace element Iodine each day.

13. Explain why water is a polar molecule. Water is a polar molecule because it’s opposite ends have opposite charges. Sketch and label a water molecule:

14. If given one water molecule, be able to sketch 3 additional water molecules. Draw this:

STOP How do we know all this? Indirect evidence: gathering info about something you can’t see through experiments Ex.) guessing what is inside the box Based upon indirect evidence, models of the atom have been created, tested, and improved.

Chemical reactions can either break or form new bonds between compounds All of the chemical reactions that occur within an organism are referred to as the organism’s metabolism

Mixtures A combination of 2 or more things that are not chemically combined. Easy to separate based on physical properties

15. What values on the pH scale are acidic, basic, neutral?

Acids & Bases Acids and bases are important to living systems Acids pH < 7 and forms hydrogen (H+) ions in water Bases pH > 7 and forms hydroxide (OH-) ions in water

16. Does an acid have more or less hydrogen ions (H+) than hydroxide ions (OH-)? Base? Neutral? Acid = more H+ (H+) > (OH-) Base = more OH- (H+) < (OH-) Neutral = equal (H+) = (OH-)

17. Is something with a pH of 3 more or less acidic than something with a pH of 4? MORE Acidic

18. Describe what happens when acids or bases are added to a buffer solution. Buffer solutions are used as a means of keeping pH at a nearly constant value. Many life forms thrive only in a relatively small pH range so they utilize a buffer solution to maintain a constant pH.

19. Name one place in your body that you could find a buffer and why it’s important. One example of a buffer solution found in nature is blood. Important so that our bodies can probably use nutrients from the different foods/liquids we eat/drink everyday.

20. Describe 5 properties of water that are important to life. Cohesion and Adhesion: Temperature Moderation Low density of Ice Ability to dissolve other substances Buffering of pH (acids and bases) - Use book or online to find out WHY for each answer above…(homework).