1. The Chemistry of Life Or Biochemistry Atoms, Molecules, Compounds, Chemical Bonds

2. Atoms atom: smallest particle of element w/ all properties of that element; basic unit of matter nucleus: center of atom which contains protons (positively charged particles) and neutrons (carry no charge) electrons: negatively charged particles outside nucleus element: composed of only 1 type of atom (92 elements in nature)

3. Atoms electrons nucleus

4. Isotopes isotope: atom of same element w/ different number of neutrons (e.g., carbon-12, carbon-13, carbon-14) Isotopes of carbon

5. Molecules & Compounds molecule: group of atoms held together by covalent bonds; smallest unit of most compounds compound: substance composed of atoms of different elements chemically combined

6. Chemical Bonds covalent bond: chemical bond formed when 2 atoms combine by sharing electrons (e.g., H2O) ionic bond: force of attraction between oppositely charged ions (atoms that gain or lose electrons); electrons are transferred (e.g., NaCl)

7. Covalent Bonds

8. Ionic Bonding Sodium atom (Na)Chlorine atom (Cl)Sodium ion (Na + )Chloride ion (Cl - ) Transfer of electron Protons +11 Electrons -11 Charge 0 Protons +17 Electrons -17 Charge 0 Protons +11 Electrons -10 Charge +1 Protons +17 Electrons -18 Charge -1

9. Properties of Water Hydrogen Bonds hydrogen bond: bond formed between molecules by attraction of opposite charges between hydrogen and oxygen (e.g., bond between H 2 O molecules)

10. Chemical Bonds in Order of Increasing Attraction (increasing attraction) hydrogen covalentionic