Topic 1: Chemical Bonding and Water; pH, Acids, Bases and Buffers; the Metric System

Covalent Bond

strongest bond, one pair of elections shared between outer shells of two non-metal atoms, intermolecular,

Polar Covalent Bond

sharing electrons between one low electronegative molecule and one high electronegative molecule

Non polar covalent bond

electrons shared equally between two atoms occur when bonding partners have similar electronegativity.

Intermolecular interaction

types of forces of attraction between molecules ex. H2O

Intramolecular interaction

forces that bind atoms together to form molecules

Dipole

determines which element in the molecule is more electronegative.

Ionic bond

extremely electronegative atom “steals” electrons from its bonding partner, nonmetal + metal

Dipole - Dipole Interaction

Occur between polar molecules where the positive end of one molecule is attracted to the negative end of another.

Hydrogen bond

Hydrogen is directly bonded to N, O, or F and can interact with H, N, or F, made possible by a covalent bond and a type of dipole-dipole interaction.

London dispersion

weakest bond and temporary bond, over short distances,can occur between any two elements.

Hydrophilic

polar covalent molecules and ionic compounds that are soluble in water, like water

Hydrophobic interaction

nonpolar molecules insoluble in water

pH

The power of hydrogen in a solution, a logarithmic scare where the pH number is inversely proportional to hydrogen ion concentration

pH equation

-log [H^+]

Acid

1-6 on pH scale, high concentration of hydrogens, inverse relationship of hydrogen count and pH number

Basic

8-14 on pH scale, low concentration of hydrogens, inverse relationship of hydrogen count and pH number

Buffer

dilutes the solution making it either less acidic or basic.

Kilo unit

10³ = 1 meter

centi unit

10^-2 = 1 meter

milli unit

10^-3 = 1 meter

micro unit

10^-6 = 1 meter

nano unit

10^9 = 1 meter

angstrom unit

10^10 = 1 meter

how do atoms interact via covalent and ionic bonds

Covalent bonds share atoms between two elements, while ionic bonds give and take atoms to fulfill their valence shell

why is water is an ideal solvent for biological systems, with reference to properties
derived from its ability to form hydrogen bonds.

hydrogen bonds are continuously breaking and reforming. They also dissolve easily in water. Polar covalent bonds also make hydrogen bonding possible and hydrogen bonding has dipole dipole interactions that are super important.

what is the importance of buffers in biological systems

they help prevent changes in pH by accepting or releasing protons to maintain constant pH

5 Properties of water

water cohesive (likes to be together)

Water has a high heat capacity (high boiling point)

Water has a high heat of vaporization (a lot of energy to become a gas)

Water is less dense as a solid than a liquid

Water is a good solvent for polar molecules