Chapter 2: Chemistry and Life

1. Chapter 2: Chemistry and Life Jannette Van Brakel

2. Cells that make up living things are able to function as they do due to a series of chemical rxns. Function at the cellular as acquired by chemistry and it requires: Repulsion Bonding Latching Reforming Depositing Breaking down Life is carried on by a chain of chemical reactions.

3. Energy and matter Matteranything that takes up space and has mass ( the quantity of matter in any object). How much volume and how dense is that object within a space? What is Chemistry concerned with?

4. How far can something be broken down into? Think of something that you eat. What does your body break it down into as a usable source? How far does it get broken down? Plato all matter was made up of Earth Air Fire Water Democritus believed that all substances were made up of smaller subunits both invisible and indivisible-they could not be broken down further. He called these units Atoms *He was correct with the exception that the were divisible. 2.1 The nature of matter the atom

5. The building blocks of life atoms

6. Three constituent parts of an atom Protons positive charge Neutron no charge Electron negative charge # of protons = # of electrons Protons and neutrons are packed together in the core nucleus Accounts for almost all of the mass of an atom Electrons move around the core some distance away Protons, neutrons, and electrons

7. Example: What is it that differentiates iron from gold? Iron26 protons Gold79 protons How is one object different from the other as it applies to matter.

8. Elementa substance that is “pure” because it can not be reduced to any simpler set of component substances through chemical process. Example: Gold It is an element Any element that has 79 protons in its nucleusgold. A gold bar has identical atoms with 79 protons in its nucleus. **Gold can not be reduced to a simpler element because P+, N, and E- can not exsist by themselves as matter Example Helium =2protons Hydrogen=1p Helium does not loose a proton to become hydrogen. Fundamental Forms of matter: The element

9. Atomic number= Number of protons 1=Hydrogen, 2=Helium…….92=Uranium So what is a handful of Earth or anything else composed of? Assigning number to the elements

10. Recall Atoms Same number of protons and electrons Neutrons add weight Neutrons can vary independently of the number of protons. When the number of neutrons vary, we can have various forms of the element calledIsotopes Isotopes

11. Hydrogen= 1p Hydrogen Isotopes 1. Deuterium= 1p+1n 2. Tritium= 1p+2n Carbon= 6p+6n Carbon Isotope 1. Carbon 14 Isotope= 6p+8n Isotopes: Examples

12. How isotopes are used in body imaging. • Tc technetium • Emits gamma rays • Incorporate themselves into antibodies • The antibodies then bind to cancer cells • Also used for detecting circulatory system disorders and gastrointestinal bleeding sites.

14. Help elements combine with other elements. The importance of electrons

15. Chemical bonding Chemical combination and rearrangement Two atoms come together e-in each atom reshuffle themselves One atom Gives up one or more e- Accepts one or more e- When electrons are shuffled around bonds are formed Giving up an e-  Ionic bonding Sharing an e- Covalent bonding Hydrogen Bonds 2.2 Matter is transformed through chemical bonding

16. Bonds occur when Atoms seek a more stable state Example; A boulder on a hill high energy If pushed falls A boulder at the bottom of a hill  lower energy Will not move up The energy in atoms is electrical energy When they bond together they are at a lower energy state They accomplish this by filling up their outer shells with e- *Think of how water acts as a vapor VS liquid state Energy always seeks its lowest state

17. Outer shells Well defined “energy levels” outside the nucleus of an atom. Energy levels differ depending on the element Hydrogen has 1 energy level 1 electron But the first energy level must have 2 e- in order for it to be stable *therefore it must accept an e- or give up an e- The second energy level must have 8 e- Seeking a full outer shell: Covalent Bonding

18. H2O 2 atoms/Hydrogen 1 atom/Oxygen Hydrogen 1 energy level/ 1 e-= First energy level needs to be filled only 1e- Oxygen 2 energy levels/ 8 e- = First energy level is filled2 e- Second energy level needs to be filledonly 6 e- How many e- does H and O need in order to fill up their shells? H1 O2 How Chemical Bonding Works in one Instance:Water

20. Matter is neither created or destroyed in a chemical reaction The atoms are now bonded and it is now called a molecule Law of conservation of mass

21. When two or more atoms combine to form a covalent (sharing of e-) rxn 2 H atoms+1Oatom= 1 water molecule Can be 2 of the same elements H+H Can have many elements Sucrose table sugar C12H22O11 What is a molecule?

22. In a covalent bond e- can either be shared equally or unequally. Equal sharing H-H molecule= nonpolar covalent bond The electrons of the atoms are equally attracted to each other Unequal sharing H2Omolecule= polar covalent bond Oxygen has the greatest amount of e- therefore it attract more e- electronegativity Electrons are pulled away from the H and take on a different electrical charge polarity Therefore the charge on the oxygen will be slightly negative and the charge on the Hydrogen will be slightly positive Polar and Nonpolar Bonding

23. Polar water molecule • Exposed partial charges allows for other water molecules to join by hydrogen bonds • Nonpolar methane molecule • The charges balance each other out and there is no positive end and no negative end • *** This is why oil and water don’t mix

24. Occurs when The electronegativity of one atom is greater then the other atom that its electron is lostionic bonding Example: Third shell is unfilled we need 8 Sodium/Na11e- (1 extra electron)2,8,1 Chlorine/C/17 e- (7 extra electrons)2,8,7 Solution? Ionic Bonding: When electrons are lost or gained

25. Chlorine very electronegative Na+ looses an e- becomes positive Cl- gains an electron becomes negative Opposites attract NaCl crystalsTable salt

26. Cl- picked up an e- and gained a negative charge Na+ lost an e- and became positively charged. Ion When an atom becomes charged Looses or gains electrons Ionic compounds are formed when Two or more elements are bonded up down and sideways from each other. What is an Ion?

27. Remember a water molecule has 2 partially charged +H and –O So what happened when you have more then one water molecule? They are attracted to the neighboring water molecules Hydrogen bonds links an already covalently bonded hydrogen atom with an electronegative atom. **Weak bonds A Third Type of Bond: Hydrogen Bonds

29. Why does molecular shape matter? Enables biological molecules to carry out activities Determines the ability to latch or bind to one another Example: The fresh smell of bread Bread gas molecules travel through air and latch on to receptor in your nose. The precise shape of the gas and the receptor is needed in order to send the “Bread” message to your brain. Molecular Shape Is Very Important in Biology

31. What happens to salt when you add it to water? It is mixed If it has mixed uniformly, so that there are no lumps then you have a solution- a homogeneous mixture of two or more kinds of molecules, atoms or ions The salt that is being dissolved solute The water is doing the dissolving, so it is thesolvent Solutes, Solvents, and Solutions

32. Solubility of an atom is determined by whether chemical bonds are formed A general rule ***Like dissolves like A polar solute dissolve best in a polar solution Water and salt A nonpolar solute dissolve best in a nonpolar solution, Soap and grease or dirt Solutes, Solvents, and Solutions

34. Essays Notating Chemistry Free Radicals