Basic Chemistry & Chemical Bonds

Subatomic Particles Proton (+) Electron (-) Neutron (n) Nucleus of an atom contains protons and neutrons Electrons orbit the nucleus

Periodic Table Used to organize elements using their subatomic particle information

Elements Pure substance of only one atom

Compound 2 or more elements combined Some other examples? Sodium chloride (NaCl)… salt

Covalent Bonds Electrons are shared Example: water (H 2 O)

Ionic Bonds Electrons are exchanged Example: sodium chloride (NaCl) or salt

Hydrogen Bonds Weak and break easily

Polar Molecules 1 part (+) 1 part (-) soluble in other polar compounds, and insoluble in non-polar compounds. Example: H 2 O

Non-polar Molecules The charges all cancel out each other Example: CO 2

Acids, Bases, and pH Biology

pH Scale Measurement system that indicates the concentration of H+ ions in a solution Runs from 0 to 14 Compares acidity/basicity ◦A solution that has equal numbers of hydrogen and hydroxide ions is neutral and is pH 7 (pure water) Each increase in a number on the pH scale = 10X higher pH ◦Example: pH of 4 is 100X lower (more acidic) than pH of 6

Acids Any compound that forms H+ ions when dissolved in water pH of less than 7 The closer to 1, the stronger the acid Example: Vinegar

Bases Any substance that forms OH- (hydroxide) ions when dissolved in water pH greater than 7 The closer to 14, the stronger the base Example: Bleach

Why is pH important? Organisms have an internal pH that must remain fairly stable for chemical reactions to occur optimally, thus… Controlling pH is essential for homeostasis Buffers are weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH