Notes

Chapter 2:
-Life requires 25 chemical elements, 96 percent are made up of carbon, oxygen, hydrogen, nitrogen.
-Everything is made of matter, matter is made of atoms. Protons, neutrons, and electrons make up atoms.
-Atoms will fill outermost shell to become stable, matching negative electron to positive protons. Valence electrons are outermost.
-Each shell fills from the inside out. 1st shell has 2, 2nd shell has 8, 3rd has 8.
-Elements in same row in Table of Elements have same number of shells. Same column have same valence and similar chemical properties.
-Atoms tend to complete a partially filled valence shell or empty a partially filled valence shell.
-Strong bonds are covalent, weak bonds are hydrogen bonds, hydrophobic and hydrophilic interactions, ionic- transfer electron.
Covalent Bonds
-Two atoms share a pair of electrons, both atom holding onto the electrons, forms molecules.
-Two atoms can share more than one pair of electrons, double bonds share 2 pairs of electrons, triple bonds share 3 pairs of electrons. Higher the number, higher the strength.
Polar Covalent Bonds
-Pair of electrons shared unequally by 2 atoms.
-Water= o plus H
-oxygen has stronger attraction for the electrons than hydrogen, oxygen has higher electronegativity, water is a polar molecule.
Hydrogen Bonding
-Polar water creates molecular attractions, positive H atom in one H2O molecule is attracted to negative O in another H2O, can occur whenever an -OH exists in a larger molecule, weak bond