Basic Chemistry Basic Chemistry & & Chemical BondsChemical Bonds

Subatomic ParticlesSubatomic Particles

Proton (+)Electron (-)Neutron (n)Nucleus of an atom contains protons and neutronsElectrons orbit the nucleus

Periodic TablePeriodic Table

Used to organize elements using their subatomic particle information

ElementsElements

Pure substance of only one atom

CompoundCompound

2 or more elements combined

Some other examples?

Sodium chloride (NaCl)… salt

Covalent BondsCovalent Bonds

Electrons are shared

Example: water (H2O)

Ionic BondsIonic Bonds

Electrons are exchanged

Example: sodium chloride (NaCl) or salt

Hydrogen BondsHydrogen Bonds

Weak and break easily

Polar MoleculesPolar Molecules1 part (+) 1 part (-)soluble in other polar compounds, and insoluble in non-polar compounds.

Example: H2O

Non-polar MoleculesNon-polar Molecules

The charges all cancel out each other

Example: CO2

Acids, Bases, and pHAcids, Bases, and pHBiology

pH ScalepH ScaleMeasurement system that indicates the

concentration of H+ ions in a solutionRuns from 0 to 14Compares 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

AcidsAcids

Any compound that forms H+ ions when dissolved in water

pH of less than 7The closer to 1, the stronger the acid

Example: Vinegar

BasesBases

Any substance that forms OH- (hydroxide) ions when dissolved in water

pH greater than 7The closer to 14, the stronger the base

Example: Bleach

Why is pH important?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 homeostasisBuffers are weak acids or bases that can

react with strong acids or bases to prevent sharp, sudden changes in pH