IB HL Bio Unit 1 water and chem

atoms are made of

protons, neutrons, and electrons

arrangement of electrons determines

how atoms bond to form molecules like proteins or DNA

polarity arises when

electrons are shared unequally, creating partial charges

In biology, polarity determines

solubility and membrane structure

Hydrogen bonds are

Weak attractions between a hydrogen atom with partial + and EN atom like oxygen or nitrogen

Hydrogen bonding allows what properties of water

adhesion, cohesion, surface tension

Ionic bonds form when

electrons are transferred between atoms —> charged ions

Covalent bonds form when

atoms share electron pairs (ex. 2 hydrogen atoms share electron w/ 1 oxygen atom to make H2O

Polar covalent bonds form occur when

electrons are shared unequally, creating partial charges

Non-polar covalent bonds form when

electrons are shared equally

Acid:

in water, dissolves and adds H+/hydronium (charged cation hydrogen) to solution

Base:

in water, dissolves and adds OH- to the solution

pH scale (and defining values)

Below 7= acidic , 7= neutral , above 7= basic

pH scale definition

way to quantify acidity

Solvent

dissolves other things

Solute

What is dissolved

Solution

Combination of solvent + solute

How many bonds does Hydrogen, Oxygen, Nitrogen, Carbon form (HONC!)

1,2,3,4

How do HONC interact with eachother

Through covalent bonds to form organic molecules

exothermic reaction

energy releasing reactions

endothermic reactions

energy absorbing reactions (from the environment)

explain how “water is the medium of life”

water = solid, liquid, gas, allows for reactions to happen inside organisms

enables transportations of nutrients, gases, and wastes

WHY is water polar

• Due to the difference in electronegativity

• Specifically, oxygen being more polar than hydrogen pulls other molecules

Uneven distribution creates

partial negative (O) and partial positive regions (H)

Cohesion is

water molecules being attracted to one another

HOW surface tension works

liquid molecules are more strongly attracted to one another which leads to an inward force which leads to surface molecules being pulled

Adhesion is

Water molecules being attracted to polar surfaces

HOW adhesion works

Hydrogen bond causes adhesion to polar surfaces because of electronegativity of the oxygen

HOW capillary action works

adhesive forces pull liquid along surface, cohesion keeps liquid continuous, surface tension balances against gravity

What type of substacnes does water dissolve

Ionic compounds/ polar molecules by forming hydrogen bonds with them

Hydrophilic

Attracted/readily interacts with water

HOW hydrophilic

Polar molecule/ionic compound capable of forming H bonds causes attractive forces which readily interact w/ water

Hydrophobic

Repelled and NOT interacting with water

HOW hydrophobic

non-polar molecule that does not possess charged regions so it cannot interact

Solvent properties related to metabolism

Water dissolves charged molecules (ions from nutrients) which keep them mobile and allow them to interact in the cytoplasm

How is minerals and sucrose transports in plants

Via capillary action through the xylem (dead plant tissue) and the water goes up the roots

NaCl in blood

Since its ionic compound= highly soluble

disassociates Na and Cl into plasma

Amino acids in blood

soluble and polar

Waters polarity allows it to form hydrogen bonds w/ AA , dissolve, transported thru plasma

Glucose in blood

Highly soluble

Waters polarity dissolves polar glucose by forming hydrogen bonds—> transported thru plasma

Oxygen in blood

Slightly soluble

Mostly carried via hemoglobin not water

WHY: Oxygen is NOT polar so it forms weak bonds with weak interactions

Fat in blood

Insoluble

Transported via lipoproteins

Fats are non-polar so it lacks attraction needed to bond with water

Physical property

measurable characteristic of a subsance (ex. viscosity, density)

explain buoyancy

because fluid pressure increases with depth, greater upwards force is applied on the objects bottom than downwards force on objects top

causes animals to adapt by developing fat in order to not die

explain viscosity

how easy a liquid can flow

caused by internal friction

water has a low viscosity

Low viscosity makes water habitable

explain thermal conductivity

how easily heat can pass through something

water has a high thermal conductivity

fur (adaptation) has a low thermal conductivity

explain specific heat

amt of heat needed to raise temp of 1g by 1 C

heat energy breaks bonds and releases energy

regulates temperature in nature (ex. large body of water)

compare and contrast air and water

air:

• changes temp quicker

• lower specific heat

water

• denser and more viscous

• better for transporting heat (can absorb more heat without internal temperature rising as much)

explain water as a coolant in sweat

evaporation of water absorbs heat

regulates body temp

higher temp water molecules escape into the air

heat from skin—>absorbed by liquid sweat —> energy changes into water vapor

water and density explained

solid form = less dense than liquid form

when liquid: water molecules in constant motion, allowing H bonds to be formed and broken repeatedly

when frozen: water molecule movement slows down and H bonds become solidified

higher temp = lower density

extraplanetary origins of water

delivered via astroids, comets

plate tectonics and volcanic outgassing recycle water

earths gravity and magnetic field help retain water

Water=search for extraterrestrial life

water = hints at possibility of similar life elsewhere