Biology lesson 2

What is the leading hypothesis for the origin of life on Earth

Chemical evolution

explain chemical evolution

simple atoms resulted in more complex carbon containing molecules resulting in a molecule that could replicate itself, as replication occurred so did natural selection

four atoms that make up 96% of matter

hydrogen carbon nitrogen and oxygen

non polar covalent bonds and symmetry

symmetrical

where did chemical evolution likely originate

in water based environment, life is based on water

each proton and neyutron are similar in mas and weigh has a mass of..

one dalton

atoms with the same atomic number have what in common

same chemical properties and belong to same element

the number of unpaired electrons is called the

valence of an atom

what do valence electrons contribute to

the chemical bonding

when are atoms most stable

when their outer shell is full by the formation of chemical bonds

molecules

held by covalent bonds

compund

atoms of different elements are held together and may not be shared eq

electronegativity

strength in which they attract electrons to their nuclei

where on the periodic table is there a higher electronegativity

up and right

what’s electronegativity determined by

the distance of the valence shell from the nucleus, and number of protons in the nucleus

two types of covalent bonds and what they are

non polar covalent: equal sharing (c-h)

polar : un equal sharing (o-h)

ionic bonds

electrons are transferred by one atom to another because it gives the resulting atoms a valence shell

solute and solvent

solvent: water

solute: salt

what makes water such a good solvent

the partial neg charge, the hydrogen have partial positive, the charges are at opposite ends. therefore, partial neg attracts partial positive hydrogen which creates hydrogen bonds

cation v anion

c: loses to become positive

a: gains to become negative

hydrogen bonds

when the partial negative of an oxygen attracts the partial positive of an hydrogen— weak electrical attractions

hydrophilic vs hydrophobic and whether they are polar or not

philic yes they are polar

phobic no they are non polar

waters properties

cohesion

adhesion

denser as a liquid than solid

absorbs large amount of eng

cohesion

bind to itself via hydrogen bonding to create factors like surface tension

adhesion

water binds to other such as glass or plastic

more dense as liquid

most substances shrink while becoming slid but water expands and is more dense as a liquid than it is as a solid creating a crystal structure hence why ice floats on water

water molecules dissociate into

hydrogen and hydroxide happening at both directions equally (equilibrium), as protons don’t exist alone it allows for the creation of hydronium ions

what is produced by water molecule disassociation

hydronium ions

acids

give up protons which raises hydronium (adding an ion raises the proton concentration)

bases

acquire protons during them rxn and lower hydronium concentration

buffers

minimize change in pH and sustain homeostasis

energy

capacity to do work or supply heat

kinetic v potential eng

potential, stored potential to do work

kinetic, active energy of movement

in molecules what is potential eng related to

position of shared e in covalent bonds

chemical eng

molecules potential to become stronger

what happens when u go polar to non polar

potetuak energy increases

position of share e from atom nuclei

closer to one or both : strong (ionic)

shifted far from atom nuclei long an weak bonds

thermal eng

kinetic energy of molecular motion

heat

measure of thermal energy being transferred between two objectsf

first law of thermodynamics

energy is conserved, it cannot be created or destroyed just transferred or transformed

chemical spontaneously rxn

they happen without external influence

ex: ball roll down hill

what direction do physical and chemical processes proceed in

the result that results in lower potential eng and increased disorder

spontaneity of reaction determined by

1. product are less ordered than reactants(entropy increases)

2. products have lower potential eng than reactants

second law of thermodynamics

entropy always increases

carbon

super versatile - 4 e allowing it to bond multiple types

org compounds

molecules that contain carbon bonded to other elements

chlorine has a charge of -2 what does that indicate

gains two electrons

what makes a solution

solute dissolved in a solvent

solute is

what gets dissolved

solvent is

what surround the solute

when a substance is dissolved in smth like water

they are more likely to react as water os a good solvent

descrive water

it is polar oxygen has partial neg, hydrogen has partial positive allowing hydrogen bonding

hydrogen bonds only in reference to water?

no, they can form between hydrogen and any other polar molecule

hydrophilic “water loving” descriptiom

they are ions and polar molecules present in solution in which are able to interact w partial charges

hydrogen bonding makes what possible

makes it possible for any polar molecule to dissolve in water

hydrophobic “water fearing”

they are uncharged molecules that do not dissolve in water

acids have a ph of

less than 7

bases have a ph of

greater than 7

in molecules what happens if shared electrons are far from nuclei

bonds are long and weak

in a molecule what happens if the electrons are shifted closer to one or both nuclei

the bond becomes shorter and stronger

2 q that are fundamental in learning how simple substances could have evolved yo such complex structures

1. what is the physical structure of hydrogen, carbon, nitrogen and oxygen found in cells

2. what is the structure of simple blocks like h20 and c02 that served as building blocks

how are atomic no, and mass organize

atomic number: subscript left

mass: left but up

carbon 14 with 8 neutrons

represents a radioactive isotope in which the nucleus will decay and release energy in the form of radiation

what happens to c14 when it decays (n and p)

neutrons change to protons making it a different element

define ion

atom or molecule that carries a full charge rather than a partial charge that come from polar covalent

methane

CH4 commonly found in gas

atoms w more than one unpaired electron

can form double or triple bonds

double bond

2 pairs of e shared whilst triple bond is 3 pair of e is shared

molecular formulas

indicate numbers and types of atoms in a molecule

structural formula

indicate which molecule are bonded tg (dingle double and triple),,, also indicates geometry in 2 dimensions

how much volume in a cell is water

75%

chemical reaction equations

reactant left and result right,

water molecule chemical exp

disassociation

dynamic stable state as chemical run

chemical equilibrium

molarity

number of moles of the solute present per litre

endothermic rxn

thermal energy is absorbed by system during process

exothermic run

release of thermal energy to the environment

prebiotic soup model

certain molecules synthesized from atmosphere via meteorites

surface metabolism model

dissolved gasses come in contact with minerals lining walls of deep sea vents