1. Chapter 2 The Chemical Context of Life

2. Chemistry Definition –Study of matter and its transformations Matter –Has mass and occupies space Transformations –Chemical reactions –Break or form chemical bonds

3. Units of Matter Element –Substance that cannot be broken down further by chemical means Compound –Substance composed of more than one element Molecule –Substance composed of more than one atom –Includes diatomic elements

4. Elements found in Living Organisms 98 % of living mass composed of 4 elements –Oxygen –Carbon –Hydrogen –Nitrogen Minerals Trace elements

5. The Atom Basic Unit of Elements Most fundamental unit of an element that retains the properties of the element Structure determines properties of element Composed of sub atomic particles

6. Subatomic Particles Proton Neutron Electron

7. Protons Composed of quarks –2 ups and a down –http://en.wikipedia.org/wiki/ Quarkhttp://en.wikipedia.org/wiki/ Quark Positive charge of +1 Mass of 1 AMU or Dalton Resides in atomic nucleus Confers identity Atomic number

8. Neutrons Composed of quarks –2 downs and an up Electrically neutral Mass of 1 AMU Resides in atomic nucleus Stabilizes atomic nucleus Contributes to atomic mass Number varies Isotopes

9. Quarks and Leptons both Fermions

10. Isotopes Forms of an element that differ in the number of neutrons Atomic mass changes but atomic number does not May be radioactive if atomic nucleus is over crowded

11. Isotopes

12. Common Radioactive Isotopes

13. Types of Radioactive emissions Alpha –Helium nucleus –2protons, 2 neutrons Beta –Electron equivalent –Neutron converts to proton Gamma –EM radiation –Accompanies other particles G -

14. Electrons Fundamental particle called a lepton http://en.wikipedia.org/wiki/Lep ton http://en.wikipedia.org/wiki/Lep ton Electrical charge of -1 Mass negligible( 1⁄1836 of that of the proton) Located outside the atomic nucleus in the electron cloud Neutralizes the charge of the protons Participates in chemical bonding

15. Electron location within the Electron Cloud Distance from atomic nucleus indicates electron energy level The farther from the nucleus, the higher the energy Levels called shells (1 st quantum number,N) Named as numbers (1,2,3…) Maximum number of electrons in each shell= 2N 2 Outer shell=valence shell Outer shell electrons most readily available for chemical bonding

16. Electron location within the Electron Cloud Orbitals (2 nd quantum number (l) Specific region in which an electron is likely to be found Named with letters –s- sharp –p-principal –d- diffuse –f-fundamental –Named after groups of lines in the spectra of alkali metals

17. Electron location within the Electron Cloud Shapes of orbitals s spherical- 2 electrons p party balloons- 6 e - d complex 10 e - f complex 14 e - Energy increases from s-f Electrons usually fill from s→f with some exceptions 3 rd quantum number is the axis or magnetic orientation of the orbital (m)

18. Electron Fill Electron configuration of an element Fill from lowest energy to highest energy location Opposite spins for electrons in same orbital (Pauli exclusion principle) Spin is the 4 th quantum number (s)

19. Sub Atomic Particles ProtonNeutronElectron Mass (kg)1.6726231x 10 -27 1.6749286x 10 -27 9.1093897x 10 -31 Charge [C]+1.6020.0- 1.602 Radius8x10 -16 less than 10 -16 Compositio n uuddduN/A

20. Periodic table Periods –Horizontal rows –Represent electron filling of a shell –Fill from left to right –s 1 st 2 groups –d transition metal –p right block, metaloids, non metals –f lanthides and actinides

22. Electron configurations C N O Li Cl F Ne

23. Bohr Model C N O Li Cl F Ne

24. Chemical bonding Forms by interactions between valence shell electrons Goal- full valence shell Two main types –Ionic –Covalent Type determined by electro negativity differential

25. Ionic Bonds Electron transfer Large electro negativity differential Between metals and non metals Ions formed –Cation –Anion Attraction between oppositely charged ions

26. Covalent Bonds Electrons shared between atoms Low electro negativity differential Hybrid orbitals Electron timeshare Single Double Triple

27. Polar Covalent Bonds Electrons not shared equally Creates a dipole Rotates in electrical field Fosters dipole interactions

28. Non-Polar Covalent Bonds No separation of charges Equal electron sharing Even distribution of charges Fosters induced dipole interactions

29. Dipole Interactions Occur between polar covalent molecules Stronger than interactions between non- polar molecules Slightly negative region of one molecule is attracted to slightly positive region of a neighboring molecule Cohesive

30. Hydrogen Bonds Special type of dipole interaction Involves H as the slightly + component Very significant in biological systems –2 strands of DNA –Protein shape –Genetic code

31. Induced Dipole Interactions May be referred to as Van der Waals interactions Very weak Between non-polar covalent molecules Volatility of non-polars compared to polars

32. Induced Dipole Interaction

33. Solubility Like dissolves like Test for polar substance- dissolve in water Non polar solvents clean non polar stains Polar solvents clean polar stains Oil and water