BIO 190- Chapter 2 *Chemical Basis of Life* :)

what is matter

all material in the universe that has mass and occupies space

solid, liquids, and gasses

what are atoms

the smallest functional units of matter that form chemical substances

what is a molecule

2 or more atoms bonded together

what is an element

a pure substance made up of only 1 kind of atom

what are the 3 subatomic particles

protons, neutrons, electrons

where are the 3 subatomic particles found and what are their charges

protons= positive and found in nucleus

neutrons= no charge and found in nucleus

electrons= negative and found in orbitals around nucleus

describe the amounts of protons, neutrons and electrons

# of electrons = # of protons

what is a orbital

the region surrounding a nucleus where the probability is high to find an electron

what is the atomic number

number of protons

describe the mass of protons, electrons and neutrons

protons and neutrons are nearly equal in mass whereas electrons mass are generally ignored

one mole of an element contains how many atoms

6.022 x 10 ^23

Name the 4 elements that are abundant for most living organisms (about 95% of total mass)

carbon, hydrogen, oxygen and nitrogen

Remember: CHON

what is atomic mass

protons + neutrons

compound

molecule composed of two or more different elements

ex: H20

atoms in molecules are held together by _______________

chemical bonds

what are covalent bonds

atoms share a pair of electrons

" a strong handshake, each is now 1 electrons richer*

describe the strength of covalent bonds

strong because the shared electrons behave as if they belong to each other

octet rule

many atoms are most stable when they have 8 electrons in their outermost shell

double bonds

the sharing of two pairs of electrons between two atoms

what is electronegativity

a measure of its ability to attract electrons in a bond with another atom

what are non polar covalent bonds

equal sharing between atoms with equal electronegativity

What are polar covalent bonds?

unequal sharing of electrons because one electron is more electronegative

the more electronegative electrons is "richer" in the handshake, one side pulls more electrons toward it

why is water a very polar molecule

due to the difference in electronegativity between oxygen and hydrogen, and the bent shape of the molecule

what is a hydrogen bond

interactions between a hydrogen with a partial positive charge and another electronegative atom

partial positive and partial negative charge

what is the strength of a hydrogen bond

very weak unless there are many H bonds

what are enzymes

protein that acts as a catalyst to speed up chemical reactions in a cell

what is an ion

an atom or molecule with a net electric charge due to the loss or gain of one or more electrons.

what are cations

an ion with a net positive charge

what is a anion

an ion that has a net negative charge

describe an ionic bond in terms of electrons

give away and donate elctrons

describe the shapes of molecules

3-D flexible shapes allow them to interact and contribute to their biological properties

what chemical bonds dissolve in water

ionic and polar covalent bonds

when does a chemical reaction occur

when one or more substances are changes into other substances by making or breaking of chemical bonds/ and or addition of electrons

what are the similar properties of chemical reactions

- require a source of energy

- must be catalyzed

- tend to proceed in a particular direction but eventually reach equilibrium

- usually occur in watery environments

reactants vs products

Reactants are substances that start a chemical reaction. Products are substances that are produced in the reaction.

chemical equilibrium

a state in a chemical reaction in which the rate of formation of products equals the rate of formation of reactants

what are solutes

a substance that dissolves in a liquid

what is a solvent

the liquid in which a solute is dissolved

in all living organisms the solvent for a chemical reaction in _____

water

what is a solution

a liquid that contains one or more dissolved solutes

what is a aqueous solution

solution made with water

describe the charges in H20

covalent bonds link the two hydrogen atoms to the oxygen atom in a molecule of H20 are polar

oxygen has a slight negative charge and hydrogen has a slight positive charge

generally what type of molecules dissolve in water

ionic and/or polar covalent bonds

what type of molecules are hydrophilic

will dissolve in water "water loving", have a partial charge

ex: ions and polar molecules

what does hydrophobic mean and what type of molecules are hydrophobic

molecules that do not have a partial charge and are not attracted to water molecules,

ex: non polar covalent bonds

what does amphipathic mean

having both hydrophilic and hydrophobic regions

what is solute concentration

the amount of solute dissovled in a unit volume of solution

what is unique about water

in exists in all 3 states (liquid is most common)

describe waters specific heat

amount of energy to raise the temp of 1 gram of a substance by 1 degree celcius

water has a high specific heat meaning it takes a lot of heat to raise the temo

heat capacity

the amount of heat needed to increase the temperature of an object exactly 1°C

why is water relatively stable in large bodies of water

specific heat and heat capacity

colligative properties

properties that depend on the concentration of solute particles but not on their identity

cohesion

Attraction between molecules of the same substance

(water exhibits strong cohesion due to hydrogen bonding)

adhesion

An attraction between molecules of different substances

(ability of different molecules to be attracted to each other, water tends to adhere to surface in which it can hydrogen bond)

surface tension

measure of the attraction between molecules at the surface of a liquid

high specific heat, surface tension, and cohesion are several properties of water involving ________ bonds

hydrogen

in pure water concentrations of H+ and OH - are what

10 ^-7

what are acids

molecules that release hydrogen ions in a solution

strong acid

acid that completely ionizes in a solution

weak acid

acid that only partially ionizes

base

molecule that when dissolved in water lowers the H + conentration

pH

mathematical expression of a solutions hydrogen ion concentration defined as the negative logarithm base 10 of the H+

acidic solutions

pH below 7

alkaline solutions

pH above 7

buffer

minimizes pH fluctuations

a buffer is composed of .....

weak acid and its related base

sum of the atomic masses of all the atoms of a molecule

molecular mass

when more H+ is added , the pH .....

decreases

what properties of water result from hydrogen bond formation

high specific heat, cohesion, adhesion, surface tension, high heat of evaporation

name the 3 types of chemical bonds

ionic, covalent, hydrogen

when do atoms become ions

when they give away or take ONE electrons to achieve a complete valence shell

describe ions in water vs out of water

ions are free and fully charged in water but when water evaporates positive and negative ions attract and ions become solid

name 3 examples of non polar covalent bonds

C-H, O-O, C-C

name 4 examples of polar covalent bonds

O-C, O-H, C-N, N-H

describe the electron cloud in a polar covalent bond

the atom with higher electronegativity will pull its partners electrons closer to its nucleus

one atom will always be more positive and one will be more negative

compare non polar and polar covalent bonds relationship with water and give examples

non polar molecules repel water (hydrophobic) such as oils, fats, waxes

polar molecules attract water (hydrophilic) such as sugars, proteins, salts etc.

if an atom becomes an ion what will happen

it will loose or gain an electron

if an atom becomes a isotope what would happen

it would loose or gain a neutrons

why does table salt dissolve in water

the water breaks the bonds of Na and Cl

why does oil (lipids) not dissolve in water

because water is polar and the oil/lipids are non polar. they are opposite so they molecules do not attract

would a low pH be acidic or basic

acidic (lots of hydrogen ions)

would a high pH be acidic or basic

basic (not a lot of hydrogen ions)

describe the importance of stomach pH

trypsin a protein made by your stomach breaks down food and binds to h+ ions to achieve an active shape when food moves to intestine the pH increases which changes the shape making trypsin inactive

what increases H+ and what decreases H+

acids increase, bases decrease

your blood and stomach are heavily ....

buffered to prevent pH changes