BIOL 1020 - Lecture 5: Chemistry Review

Summarize the structure of an atom

Relate atomic number, atomic mass, isotopes and ion to an atom

Determine the number of valance electrons an atom has by its atomic number

• atoms are composed of neutrons, protons, and electrons

• atomic number: number of protons in the atom

• atomic masss: sum of the protons and neutrons in the nucleus

• isotope: same number of protons, differing number of neutron

• ion: charged atom (lose or gain electron- cation or anion)

Compare and contrast ionic and covalent bonds

• Ionic bonds are formed between ions (charged atoms)

• transfer of electrons from metal to nonmetal

• held by chemical bonds

• covalent bonds are formede between two nonmetals to form a molecule

• localized sharing between elements to form moleculess

• can have single or double bonds

predict the polarity of a molecule based on its structure

• polarity can be based on electronegativity

  • there are nonpolar covalent bonds, where the electrons are shared equally due to equal EN, and polar covalent bonds. where electrons are shared unequally due to one atom being more EN than the otheer

• in order for a molecule to be polar it must have

  • polar bonds

  • unsymmetrical shape (so there is a net dipole)

Bonding

• Hydrogen bonds

• van der waal interactions

these give the molecule a specific shape

Explain how pH related to hydronium and hydroxide concentrations

• acids increase [H] by disassociating to release H+

• bases reduce [H+] by accepting H+ ions and dissociating to produce excess H+

outline the emergent properties of water that make it essential for life

• water molecules can stay together

• water moderates temperature due too its high specific heat capacity

• solid water is less dense than liquid water (think: ice floats! h2o expands as it freezes)

• water is the solvent of life: can make solutions with solvent (does the dissolving) and the solute (being dissolve), aqueous solutions!

cohesion vs adhesion

• water molecules can stay together

  • cohesion: linking of H2O via H-Bonds

  • adhesion: clinging on one substance to another - results in surface tension