Unit 1: Chemistry of Life

elements

substances that can’t be broken down physically or chemically

elements that make up 96% of organism’s mass

1. carbon

2. oxygen

3. hydrogen

4. nitrogen

trace elements

elements required by organism in a VERY small amount

where is carbon

all macromolecules

where is hydrogen

all macromolecules

where is oxygen

all macromolecules

where is nitrogen

proteins + nucleic acids

where is phosphorus

nucleic acids + some lipids

atom

smallest building block

protons

• charge +1

• mass of 1

• found in nucleus

neutrons

• charge 0

• mass of 1

• found in nucleus

electron

• charge -1

• mass of 0

• orbits around nucleus in cloud

isotopes

same element, different mass ( = protons, /= neutrons)

compound

elements chemically combined in fixed ratio

chemical reaction

new substance formed

chemical bond

what holds atoms in compounds together

ionic bonds

transfer of electrons

covalent bonds

sharing of electrons

polar covalent bonds

unequal sharing of electrons

non-polar covalent bonds

equal sharing of electrons

hydrogen bonds

weak bonds where hydrogen in polar covalent bonds are attracted to other electronegative atom

polarity of water

very polar, partial positive hydrogen & partial negative oxygen

properties of water

• cohesion

• adhesion

• surface tension

• high heat capacity

• expansion on freezing

cohesion (water)

partially positive hydrogen attracted to partially negative oxygen in other molecules and vice versa

adhesion (water)

water sticking to other surfaces bc of cohesion

capillary action

water using cohesion + adhesion to move up in thin vessels

surface tension

water molecules stick together so light things can sit on top

types of solutions for reactions to occur in

• acidic

• alkaline

• neutral

acidic solution

contains lots of hydrogen (H⁺ ions) bc acids release them in water

alkaline (basic) solution

contains lots of hydroxide (OH^-) ions bc bases release them in water

pH of acids

1-6

pH of bases

8-14

pH of neutral substances

7

as H⁺ ions increase by factor of 10

pH decreases by 1

as H⁺ ions decrease by factor of 10

pH increases by 1

determining pH from H⁺ concentration

pH = -log [H⁺]

pH scale is

logarithmic, represents tenfold change in H⁺ concentration

organic compounds

contain carbon and hydrogen

inorganic compounds

don’t have carbon and hydrogen

why is carbon so important for life

can bond with many things (4 valence electrons)

polymers

chains of monomers

monomer

building blocks of polymers

dehydration synthesis

joining polymers by removing water

hydrolysis

breaking apart polymers by adding water

4 types of organic compounds in life

• carbohydrates

• proteins

• lipids

• nucleic acids