Unit 2: Micro and Macro Molecules

ionic bond

• tend to be between metals and non-metals

• one element (anion) takes e^- and the other (cation) loses e^-

• kept together by the electrostatic attraction in solid phase

• separates into ions when in water, forms electrolytes, and conducts electricity

covalent bond

• Tend to be between non-metals

• Both share electrons, neither forms an ion

• Kept together by shared electrons that give each atom eight valence electrons

• Does not generally separate in water, make poor electrolytes, and do not conduct electricity

How is the polarity of intramolecular bonds notated?

by 𝛿+ and 𝛿- or arrows with a plus (⇸)

electrostatic force

the attraction of opposite charges (+/-)

overall dipole

molecules that are polar overall

O-H bond

polar

N-H bond

polar

C-H bond

non-polar

asymmetrical molecule

usually polar

symmetrical molecule

usually non-polar

hydrogen bonds

water molecules are interconnected with electrostatic force due to high polarity

• notated by dashed lines

• not an actual chemical bond

intermolecular force (IMF)

attractions between molecules

intramolecular force

bonding between atoms to make a molecule (covalent, ionic)

electronegativity (EN)

the ability of an atom to draw electrons towards itself in a chemical bond

• (0-0.4) non-polar covalent: electrons shared equally

• (0.4-1.8) polar covalent: electrons not shared equally; higher EN is pulling towards itself

• (1.8-4.0+) ionic: electron is fully stripped from lower EN to higher EN

Which elements have the highest EN?

Fluorine, Oxygen, Nitrogen

solubility

the ability to be dissolved in a solvent

solvent

the dissolving agent of a solution

solute

the substance that is dissolved

aqueous solution

a solution in which the solvent is water

hydrophobic

does not dissolve in water

hydrophilic

dissolves in water

electrolyte

an ionic compound that conducts electricity in water by splitting up into separate ions

How does a solute dissolve in water?

The polar sides of water molecules attract their opposites with electrostatic force and dissolve polar covalent/ionic bonds. Ionic bonds are separated fully into cations and anions (electrolytes).

What does solubility depend on?

Size and polarity; adding more non-polar regions to a molecule will decrease its solubility in water

specific heat capacity

the amount of energy required to change a substance’s temperature

How does the specific heat capacity of water work?

Water takes a long time to boil, and it boils at a high temperature; since the hydrogen bonds are so strong, you need to add more heat to separate the bonds (to give them more heat/energy) to change them into the gas state

evaporative cooling

the heat of your body separates and evaporates the water (sweat)

adhesion

the attractive force between water molecules and other molecules ex. the sides of a beaker are more polar than water, attracting the water molecules to the sides of the beaker; makes a concave meniscus

cohesion

the attractive force between water molecules and themselves ex. surface tension

Why don’t oil and water mix?

Oil and water do not mix since oil is not polar/not attracted to water molecules and cannot break through the hydrogen bonds; the layering facilitates from the density of the liquids, where since water’s hydrogen bonds are very tight, there have a higher density than oil, causing the formation of layers.

acid base reaction

H⁺_(aq) + OH^-_(aq) = H₂O₍₁₎

acidic

more H⁺ ions, lower pH

basic

more OH^- ions, higher pH

neutral

H⁺ ions equal OH^- ions, pH of 7

acid

A substance that adds hydrogen ions (H⁺) to solutions ex. hydrochloric acid

base

a substance that reduces the hydrogen ion concentration of a solution, by either increasing the OH^- concentration or by removing H⁺ ex. sodium hydroxide base, bicarbonate base

sodium hydroxide base reaction

NaOH_(aq)=Na⁺_(aq)+OH^-_(aq)

bicarbonate base reaction

HCO^-_3(aq)+H⁺_(aq)=H₂CO_3(aq)

equilibrium

the balance between the product and reactant (⇄)

pH scale

measures the concentration of H⁺, thereby describing the acidity or alkalinity (basicity)

• lower pH means more acidic, higher pH means more basic, 7 is neutral

• the concentration of H⁺ decreases by 10x every pH level jump

weak acid

doesn’t separate very much (~5%)

strong acid

completely dissociated (~100%)

buffer

resists change in pH; a special mixture of a weak acid and a conjugate base

conjugate pair

two molecules containing the same negative ion where the base has one less carbon ex. H₂CO₃ (carbonic acid), HCO₃^- (bicarbonate)

increase in blood pH

1. H⁺ is removed from the bloodstream.

2. Carbonic acid (H₂CO₃) is used up by the body to release H⁺ and bicarbonate (HCO₃^-) into the bloodstream.

3. Since carbonic acid is being used up, the body needs more water and CO₂ to replenish the used carbonic acid.

4. The respiration rate decreases to hold onto extra CO₂.

decrease in blood pH

1. H⁺ is added to the bloodstream.

2. Carbonic acid (H₂CO₃) is made by those H⁺ reacting with bicarbonate (HCO₃^-) that is stored in the body in reserve.

3. Carbonic acid breaks down into CO₂ and water.

4. The respiration rate increases to release the extra CO₂.

abiogenesis

the idea that life came from non-living chemistry

biogenesis

the idea that life comes from life

Miller-Urey experiment

an experiment that simulates the ancient atmosphere and water cycle to test if monomers (ex. amino acids) can form from basic molecules; supported and found amino acids

spontaneous generation

theory that life is continuously coming from nonliving sources (disproved by Pasteur ex. steak/flies)

Macromolecules

large molecules important in the chemistry of life

organic compounds

carbon-based molecules

Hydrocarbons

compounds made of hydrogen and carbon (non-polar)

How many bonds will hydrogen, oxygen, carbon, and nitrogen have?

1, 2, 4, and 3/4 (can be double bonds)

isomers

molecules that have the same formula but different structures

constitutional (structural) isomers

different bonds (ex. glucose/fructose)

stereoisomers (spatial isomers)

same bonds, different organization

enantiomers

mirror images of each other (stereoisomer)

geometric isomers

different about their double bond (stereoisomer)

cis/trans isomers

require a double bond to lock into place

cis

bonds are on the same side of the double bond

trans

bonds are on opposite sides of the double bond

monomer

a small organic particle

dimer

two monomers connected through dehydration synthesis

polymer

a macromolecule composed of repeating monomers

polymerization

the process of making polymers from monomers using enzymes

dehydration synthesis

a polymer with OH- bonds with the H+ from a monomer, where the water molecule is released and the bond is held with a leftover atom(s)

hydrolysis

a reaction when water is added to a polymer, breaking the bonds between them creating monomers

structural formula

every single atom and bond is shown in the drawing

abbreviated structure

internal carbon atoms are replaced by lines/vertices

simplified structure

most carbon atoms are implied, recognized by shape

functional group

groups added to molecules that change the properties of that molecule

hydroxyl group

OH, polar, hydrophilic, hydrogen bonding site

carbonyl group

CO, somewhat polar, increases water solubility

carboxyl group

COOH, polar, hydrophilic, hydrogen bonding site, becomes negatively ionic/acidic by releasing the hydrogen

amine group

NH₂, polar, hydrophilic, becomes positively ionic/basic by taking in hydrogen

phosphate group

OPO₃^2-, polar, hydrophilic, can take ionic charge

methyl group

CH₃, non-polar, hydrophilic, decreases solubility (comes off the side of a molecule chain or ring, not the end)

sulfhydryl group

SH, somewhat polar, somewhat hydrophilic, creates disulfide bonds

carbohydrates

monosaccharides, polysaccharides, simple sugars; mixes well with water

monosaccharide

a monomer that typically has a hydroxyl group and a carbonyl group, forms polysaccharides (ex. glucose/fructose

glucose (C₆H₁₂O₆)

a monosaccharide that can come in linear (power) or ring (water) form

disaccharides

two monosaccharides connected through dehydration synthesis

sucrose

a disaccharide made of glucose and fructose

lactose

a disaccharide made of galactose and glucose

maltose

a disaccharide made of glucose and glucose

glycosidic bonds

holds two monosaccharides together

polysaccharides

made of hundreds to thousands of monosaccharides and glycosidic bonds

starch

a polysaccharide made of one strand of glucose; used by plants to story energy

glycogen

a polysaccharide made of branches of glucose; stored in animal liver and muscle cells

cellulose

a polysaccharide made of parallel glucose strands connected by hydrogen bonds; most abundant organic compound; animals do not have the enzymes to digest them (fiber)

chitin

similar to cellulose but contains an amine group; found in shells of crustaceans and in some fungi

lipids

diverse group of molecule sharing one trait: have significant hydrophobic regions

triglycerides (fats/oils)

made of a glycerol and 3 fatty acids

glycerol

a molecule containing hydroxyl groups used in triglycerides and phospholipids

fatty acid

a chain of CH₂ with a carboxyl group that reacts with glycerol making ester bonds

ester bonds

bonds between a fatty acid and glycerol

saturated

no double bonds with the most amount of hydrogen possible, straight line (fat ex. butter)

unsaturated

the carbon chain contains 1+ double bond causing bends (oil)

phospholipids

a glycerol and two fatty acids connected with ester bonds; the glycerol has one phosphate group and this molecule is used for cell walls