CHE 230 Exam 1| 110 Questions | With Complete Solutions

Friederich Wohler correct answer: Father of organic chemistry Determined that biological molecules can be synthesized in lab Carbon correct answer: Very stable Wants 4 bonds Can bond with many things Organic Compounds correct answer: Contain carbon Atoms bound by covalent bonds Essential to life! ex. amino acids; DNA Element Bond Preferences correct answer: Carbon: 4 bonds -Can be single, double, or triple Nitrogen: 3 bonds, 1 lone pair -Single, double, or triple Oxygen: 2 bonds, 2 lone pairs -Single or double Halogens (X): 1 bond, 3 lone pairs Hydrogen: 1 bond 3 Ways to Show Structure correct answer: 1. Molecular formula 2. Lewis structure 3. 3-D Structure Valence Electrons correct answer: Electrons in the outer shell of an atom For main group elements, the group number = the number of valence electrons Octet Rule correct answer: Atoms want a full valence shell of electrons -Typically 8 Hydrogen: a full valence shell is 2 electrons Covalent Bond correct answer: Sharing of electrons Steps to Draw Lewis Structures correct answer: 1. Determine central atom -Typically carbon; NEVER hydrogen -May only appear once 2. Arrange atoms around center -Add H's on last 3. Calculate total valence e- number 4. Place valence e- around the atoms as necessary -Octet rule; correct bond # 5. Form double/triple bonds as necessary Exceptions to the Octet Rule correct answer: 1. 3rd period & beyond: D orbitals -Possible to have >8 e- in valence shell 2. Boron & aluminum: only want 3 bonds and no lone pairs 3. Uneven electron number creates unstable substance Formal Charge correct answer: Use to pick the "best" structure for a molecule Formal charge = (# valence e-) - (# lone pair electrons + 1/2 # of bonds) OR: Formal charge = (# valence e-) - dots - lines