1
Q
chemistry
A
science of matter
2
Q
matter
A
all the properties of organisms depends on how atoms are arranged in molecules and how molecules are arranged in cells
- structure dictates function
3
Q
chemical element
A
substance that only contains one type of atom, different from atoms of other elements
- cannot be broken down
- 26 elements that are essential for life
4
Q
atom
A
smallest unit of matter that still retains the properties of an element
- made of 3 types of subatomic particles: protons, neutrons, electrons
- # of protons = # number of electron –> neutral charge
- atoms of different elements vary in # of subatomic particles
5
Q
proton
A
- subatomic particle of an atom
- +1 positive charge
6
Q
netron
A
- subatomic particle of an atom
- neutral/no charge
7
Q
electron
A
- subatomic particle of an atom
- -1 negative charge
- determines how an atom interacts with another atom
8
Q
atomic number
A
- # of p+ in nucleus
- unique to each element
9
Q
mass number
A
- sum of protons plus neutrons in the nucleus
- all atoms of an element have same number of p+ but may differ in number of neutrons
10
Q
isotope
A
2 atoms of an element that differ in # of neutron
11
Q
radioactive isotopes
A
nucleus decays spontaneously giving off particles and en-
- dangerous to life b/c causes mutations in DNA
- can be useful in biological research and medicine as tracers
12
Q
electron shells
A
regions surrounding the nucleus on which e- move around
- 1st shell: 2e-
- 2nd shell: 8e-
- 3rd shell: 8e-
the farther the e- from the nucleus, the more en- it has
13
Q
valence electrons
A
- e- in outermost shell/valence shell
- chemical behaviour of an atom is determined by the valence e-
- atoms in which the outermost shell is not completely filled with e- tend to be chemically reactive
- elements with full valence shell: chemically inert
14
Q
valence of an element
A
- number of e- needed to complete outermost shell
- = # of covalent bonds an element can form
15
Q
ions
A
of protons and electrons is not equal
16
Q
cation
A
positively charged ion
17
Q
anion
A
negatively charged ion
18
Q
covalent bonds
A
- forces that hold atoms together to make compounds and molecules
- sharing a pair of valence e- by 2 atoms
- very strong
- usually involves atoms with 3-5 e- in their valence shell
- forms stable molecules: full valence shell
- shared pair of e- counts as part of each atom’s valence shell
- # of single covalent bonds an atom can form = to # of addeitional e- needed to fill its outer shell
19
Q
compound
A
- substance that contains 2+ different elements
- can be broken into different types of atoms
20
Q
molecule
A
- 2+ atoms sharing e-
- can be same or different types of atoms
- involve covalent bonds
21
Q
octet rule
A
- two atoms are more likely to interact if the interaction will leave them both with 8 e- in their valence shell (full valence shell)
- atoms can donate or share e-
- enables prediction of how atoms of different elements will interact
22
Q
ionic bonds
A
- interactions between ions of opposite charge
- e- donor atom becomes positively charged and e- acceptor atom becomes negatively charged
- charged particles attracted to each other forming ionic bond
- not very strong
23
Q
compounds formed by ionic bonds
A
- not considered molecules
- composed of 2 different atoms, present in set ratio (ex. NaCl –> table salt)
- crystal lattice structure common to salts
24
Q
electronegativity
A
- atom’s attraction for the shared e- of bond (covalent)
- the more electronegative atom, the more strongly it pulls e- towards itself
- low electronegativity: C H P
- high electronegativity: O N S
25
non-polar covalent bond
when e- are equally shared
26
polar covalent bonds
when e- are not equally shared by the 2 types of atoms
- more electronegative atom becomes partially negative because it has pulled the electron from the less electronegative atom towards it
- less electronegative atom becomes partially positive because its e- has been pulled away by the more electronegative atom
27
polar molecules
- molecules that are predominantly comprise of polar-covalent bonds
- ex. sugar (has multiple hughly electronegative O atoms in polar-covalent bonds)
28
non-polar molecules
- molecules that are predominantly comprised of non-polar covalent bonds
- ex. oil (does not have highly electronegative O atoms)
29
water molecule
- polar: neutral overall but has a slightly negative pole and 2 slightly positive poles
30
hydrogen bonding
- charged region on each H2O molecules are attracted to oppositely charged region on neighbouring H2O molecules forming weak bonds
- entermolecular bonds: links btw molecules
- non-covalent interaction: no bond is formed, it's an attraction of polar regions of 2 different molecules
- very weak: constantly formed and destroyed
31
water
- inorganic compond (lacks carbon)
| - solvent of life
32
water as solvent of life
- life orginated and evolved in water
- water makes earth habitable
- most organisms live in water
- 60-90% of cell mass is water
- all metabolic processes of the body occur in aqueous environment
- water is substrate for many cellular reactions
33
water - properties
1. highly cohesive
- tendency of molecules to stick together
- creates surface tension
2. high heat capacity
- allows water to resist temperature changes
3. expands upon freezing
- allows for liquid water to remain all year round
4. versatile solvent
- dissolves a wide variety of solutes due to polarity of its molecules
34
solution
- liquid that is a homogenous mixture of substances
| - composed of solvent and solute
35
solvent
dissolving agent of solution
36
solute
substance that is dissolved in a solution
37
hydrophilic substance
- "water-loving"
- has affinity for water
- molecules are typically polar and/or charged
38
hydrophobic substance
- "water-fearing"
- does not have affinity for water
- molecules are relatively non-polar
39
hydration sphere
water forms a hydration sphere around ions, separating the Na+ and Cl- from each other and breaking the ionic bonds that held NaCl together
- ionic bonds broken down due to polar bonds in water molecules
- O in H2O surrounds Na+ ion
- H in H2O surrounds Cl- ion
water can also dissolve polar molecules
- the dissolved polar molecules remain intact in aqueous solutions b/c covalent bonds are too strong to be broken by water
40
H+ and OH-
- highly reactive
- changes in their concentration can drastically affect other cherged molecules in a cell
- H+ and OH- concentrations are equal in water
- adding acids or bases chamges their concentrations
41
acid
- chemical compound that donates H+ ions to solutions
| - the more acidic a solution, the higher the [H+]
42
base
- chemical compound that acceots H+ ions and removes them from a solution
- the more basic a solution, the lower the [H+]
43
pH scale
- measures [H+] in a solution
- ranges from 0 (most acidic) to 14 (most basic) - pH7 is neutral --> [H+] = [OH-]
- expressed in terms of negative logarithms (10x change)
44
buffer
- substances that rsist changes in concentrations of H+ and OH- in a solution
- maintain pH of solution at a constant level (not necessarily neutral) - contribute to hoemostasis
- they accept H+ ions from solution when they are in excess
- they donate H+ ions to solution when they have been depleted
45
first law of thermodynamics
en- cannot be created or destroyed; en- can only be transferred or changed from one form to another
46
energy
- capacity to do work
- transformed into useable form by enzyme-controlled chemical reactions
- 2 types: kinetic and potential
47
work
- moving things from one place to another
| - causing an alteration in something
48
kinetic energy
- en- that an object has due to its motion
| - ex. heat
49
potential energy
- en- stored in a system due to its position or configuration
- aka stored en-
- ex. chemical energy
50
reactants
starting molecules of a chemical reaction
51
products
final molecules of a chemical reaction
52
chemical reactions and energy
- en- involved every time a chemical reaction takes place
- kinetic en- can be converted to potential en- and viceversa
- potential en- stored in bonds
- en- released when chemical bonds are formed
- breakign bonds requires en-
53
catabolic pathways
- release en- by breaking down complex molecules in simpler compounds
- exergonic = release en-
54
anabolic pathways
- consume en- to build complex molecules from simpler ones
| - endergonic = requires en
55
exergonic reaction
releases en-
56
endergonic reaction
consumes en-
57
spontaneous reactions
- chemical reaction that occurs due to kientic en- of reactants
- tiny particles of matter are constantly in motion and thus bumping into each other
- if two or more molecules bump into each other with enough kinetic en-, the impact will shake up the valence e- resulting in either the formation or breaking of bonds
58
activation energy
- amount of kinetic en- required to get a reaction going
| - takes en- to break chemical bonds and initiate a reaction - supplied by kinetic energy
59
enzymes
- catalyst protein that speed up a chemical reaction by lowering the amount of activation energy
BIOL1190
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