BIOFOUND 1.6 The Chemistry of Life Part 3

two nuclei

How many nuclei are shared within a bonding orbital?

equally

how are the electrons in a bonding orbital shared if the nuclei are identical?

one pair of electrons

how many electrons does hydrofluoric acid (HF) share?

because in HF the fluorine nucleus has so many more protons

it strongly attracts that electrons

in HF the electrons spend more time around the fluorine atom so it

behaves as if it is slightly or partially negatively charged

δ^- or δ⁺

the symbol in biochemistry that indicates a slight negative charge or slight positive charge

in HF the electrons spend less time around the hydrogen atom and it

causes it to behave as if it is slightly or partially positively charged

polar covalent bonds

a type of covalent bond where the shared electrons are not equally distributed between the atoms involved

non-polar covalent bonds

covalent bonds that share equally such as in hydrogen gas

the atoms in a non polar covalent bond

do not have partial charges

electronegativity

the ability of an atom’s nucleus to attract electrons

to compare the electronegativity of each atom in a NON-POLAR bond

there must be a different between the atoms to equal to or less than 0.5

to compare the electronegativity of each atom is in a POLAR COVALENT BOND

there must be a different between the atoms of 0.5 or greater

atoms with higher electronegativity

are partially negative

atoms with lower electro negativity

are partially positive

water is a molecule built from

polar covalent bonds

the molecule is dissolved in water when

it forms hydrogen bonds with any ionic or polar covalent molecule

ions in ionic bonds are held together by the

electrical attraction between the positive ion and the negative ion

when ionic compounds dissolve in water

hydrogen bonds with weaken the electrical attraction between the two atoms

covalent bonds typically

do not break apart in water but polar covalent molecules do

hydrophillic

the term used for any molecule that can dissolve in water

hydrophobic

term for non-polar molecules that do not dissolve in water (ex. oil and water)

fats or fat-based

in living cells, most non-polar molecules are

polar molecules can dissolve

other polar molecules but not non-polar molecules

non-polar molecules can dissolve

other non-polar molecules but not polar molecules

water is NOT

the only molecule that forms hydrogen bonds, compared to other covalent bonds, they are weak!

due to hydrogen bonds being easy to form and break

cells can use them to temporarily stick molecules together and then unstick them (ex. DNA)

acids

release hydrogen ions when interacting with water

bases

attract and absorb hydrogen ions from water

negative bases

have atoms with negative charges, when they absorb hydrogen ions they become neutral

neutral bases

have atoms with lone pairs of electrons, is not in a covalent bond, when they absorb hydrogen ions, they become positively charged

pH scale

the scale that measures the acidity or alkalinity of a solution, ranging from 0 to 14. pH of 7 is considered neutral, the lower the pH is the more acidic it is.

what happens when the bonding orbital becomes distorted?

the electrons or protons end up spending more time on the side of the molecule that holds the opposite charge