Biological Science Freeman Chapter 2

Theory of chemical evolution

-explains the origin of life on Earth

-inputs of energy created complex carbon-containing molecules

-the molecule could replicate itself

Functional Group

a specific configuration of atoms commonly attached to the carbon skeletons of organic molecules and involved in chemical reactions

Catalyze

speed up chemical reactions

atomic mass

Number of protons and neutrons

non polar covalent

equal sharing of electrons

atomic number

-the number of protons in the nucleus of an atom

-written as a subscript to the left of its symbol

hydrogen bond

weak attraction between a hydrogen atom and another atom

Valance

-number of unpaired valence electrons

-atoms are most stable when valence shells are full

covalent bond

sharing of electrons between atoms

Electronegativity

-the strength with which atoms pull electrons toward themselves

-O>N>S, C, H, P

Molecule

A group of atoms bonded together, covalent

polar covalent bond

not shared equally

Cohesion

-binding between like molecules

- = high surface tension

-Example: water binds to itself by hydrogen bonding

Adhesion

-binding between unlike molecules

-Example: water binds to glass (meniscus formation)

valance shell

outermost shell

Ions

charged atoms that have gained or lost electrons

chemical reaction

substances that are combined or broken down

endothermic reaction

A reaction that absorbs thermal energy in the form of heat

exothermic reaction

A reaction that releases thermal energy in the form of heat

chemical equilibrium

In a chemical reaction, the state in which the rate of the forward reaction equals the rate of the reverse reaction

Acidic reaction

Lose electrons

Basic reaction

Gains an electron

Chemical Evolution Theory

Simple molecules present on ancient Earth reacted to create larger, more complex molecules.

*This may have happened in:

-The atmosphere

-Deep-sea vents

potential energy

stored energy

kinetic energy

active energy of movement

first law of thermodynamics

-Energy can be transferred and transformed, but it cannot be created or destroyed.

-Energy is conserved

Entropy

measure of disorder

second law of thermodynamics

-entropy always increases

-chemical retractions result in products with

-less ordered energy

-less usable energy

-physical and chemical processes proceed in the direction that results in lower potential energy and increased disorder

surface metabolism model

-air came in contact with minerals in deep-sea vents (in water)

-formed more complex organic molecules

Photons

-high-energy light energy formed from experiments

free radicals

-highly reactive unpaired electrons

-created from photons

chemical energy (type of PE)

-molecule's potential to form stronger bonds

4 Types of Matter in Organisms

-make up 96% of matter in organisms

1. Hydrogen

2. Carbon

3. Nitrogen

4. Oxygen

Basic Atomic Structure

Atoms are composed of

-Protons (positive)

-Neutrons (neutral)

-located in nucleus

-Electrons (negative)

-located in orbitals (outside of nucleus)

Atoms with same atomic number...

Are the same element

mass number

-# of protons and neutrons

-superscript to the left of symbol

mass of electron

-so small (can be ignored)

Mass of atom =

Mass Number

Atomic weight

-average of all the masses of the naturally occurring isotopes based on their abundance

radioactive isotope

isotope that decays over time

Orbitals

-what electrons move in

-each orbital holds up to 2 electrons

-orbitals are grouped into levels called electron shells

Electron shells

-levels orbitals are grouped into

-shells are numbered

-smaller numbers are closer to the nucleus

-inner most shells fill first

Valence shell

-outermost shell of an atom

-contains valence electrons

valence electrons

-Electrons on the outermost energy level of an atom

-located in the valence shell

chemical bonds

attractions that bind atoms together

Covalent Bond

-unpaired valence elections are shared by two atoms

-example: H2

Molecules

substances held together by covalent bonds

Compounds

-molecules in which atoms of different elements are held together

Ionic Bonds

-electrons are transferred from one atom to another to give both atoms full valence shells

Cation

atom loses electron and becomes positively charged

Types of covalent bonding

-polar

-don't share well (unevenly)

-O-H Bond

-non polar

-shared perfect (evenly)

-C-H Bond

Ion

-atom or molecule that carries a charge

-attraction occurs between oppositely charged Ions

Anion

atom gains an electron and becomes negatively charged

Strength of bonds (strongest to weakest)

Covalent Non polar>Covalent Polar>Ionic>Hydrogen

How are the number of Bonds determined?

-They are determined by the number of unpaired electrons

Number of bonds (strengths and lengths)

-triple bonds (shortest and strongest)

-single bonds (longest and weakest)

Molecules Shape

-dictates its behavior

-are different

-determined by geometry of bonds

molecular formula

-indicate number and types of atoms

-Example: (H2O)

structural formula

-indicate what atoms are bonded together

ball and stick model (space-filling models)

-3D geometry

Solute

the substance that is dissolved

Solvent

the substance in which the solute dissolves

Hydrogen Bonds

-weak electrical attractions

Hydrophilic

-water-loving atoms and molecules

-ions and polar molecules that stay in solution

hyrdrophobic

-water-fearing molecules

-uncharged and non polar compounds

Polar

-charges are at opposite ends of water molecule

-oxygen atoms

-partial negaitive charge

-hydrogen atoms

-partial positive charge

Water is unique due to its structure because of...

1.small size

2.bent shape

3.highly polar covalent bonds

4.overall polarity

Water is denser as a liquid than a solid

-ice floats

-water expands as it freezes

-it forms a relatively open crystal structure

Isotopes

-form of element with different number of neutrons

-have different masses

Water has high capacity for absorbing energy

-can absorb large amounts of energy

specific heat

-The amount of energy required to raise the temperature of 1 gram of a substance by 1 degree celcius

-high in water

heat of vaporization of water

-very high in water

Chemical reactions

-substance is combined or broken down into another substance

Acids

-give up protons during chemical reactions

Bases

-acquire protons during chemical reactions

molecular weight

the sum of the atomic weights of all the atoms in a molecule

mole

6.022 x 10²³ molecules

Molarity (M) (mol/L)

-concentration of a substance in a solution

pH

-proton concentration in a solution

-Basic (8-14)

-Acidic (1-6)

-Neutral (7)

Buffers

-protect against changes in pH

-help maintain homeostasis

Homeostasis

-constant conditions

Chemical Evolution may have begun in:

1. the atmosphere:

-dominated by volcanic gases

-mostly water vapor, carbon dioxide (CO2), and nitrogen (N2)

2. Deep-Sea Hydrothermal Vents

-extremely hot rocks

-gases such as CO2 and H2

-minerals with reactive metals

System

-set of interacting components

Energy

-the capacity to do work or supply heat

thermal energy

-kinetic energy of molecular motion

Temperature

-measure of the thermal energy in a molecule

Heat

-measure of the thermal energy in a molecule

Chemical Reactions are Spontaneous if...

-they occur without continuous external influence

-no energy is needed

Spontaneity of a reaction is determined by...

1. Products are less ordered than the reactants

-Entropy (disorder) increases

2. Products have lower potential energy than the reactants

-(shared electrons are held more tightly in the reactants)

prebiotic soup

-molecules are already in atmosphere gases

-rained > ended in the ocean

-ended in "organic soup" > created more complex molecules

Carbon

-most versatile atom on Earth

-4 valence electrons

-can form many covalent bonds

Stanley Miller

-found complex molecules could be formed from simple molecules

-using heat and electrical charges

-formed precursors to life molecules

fuctional groups

-amino

-carboxyl

-carbonyl

-hydroxyl

-phosphate

-sulfhydryl

amino group

-attracts a proton, acts as bases

organic compounds

-molecules that contain carbon bonded to other elements

-many molecular shapes and combinations of single and double bonds

-formation of carbon-carbon bonds was an important event in chemical evolution

carboxyl group

-drop a proton, acts as acids

carbonyl group

-sites link molecules into more-complex compounds

hydroxyl group

-act as weak acids

phosphate group

-two negative charges

sulfhydryl group

-link together via disuflide bonds