Chapter 2 Flashcards
(93 cards)
1
Q
wood ants
A
shoot formic acid to defend against invaders
2
Q
Matter consists of ___ in pure form and in combinations called ___.
A
chemical elements, compounds.
3
Q
element
A
substance that can’t be broken down to other substances by chemical reactions
4
Q
How many naturally occurring elements are there?
A
92 elements
5
Q
compound
A
substance consisting of 2+ different elements combined in a fixed ratio. (eg. NaCl)
has different characteristics from that of its elements
6
Q
essential elements
A
20-25% of the natural elements
needed by an organism to live a healthy life and reproduce
7
Q
What elements make up 96% of living matter?
A
carbon, oxygen, hydrogen, nitrogen
8
Q
trace elements
A
required by an organism only in minute quantities
9
Q
What elements are trace elements?
A
boron, chromium, cobalt, copper, fluorine, iodine, iron, manganese, molybdenum, selenium, silicon, tin, vanadium, zinc
10
Q
goiter
A
when the thyroid gland swells to abnormal size due to lack of iodine
11
Q
arsenic
A
poisonous to humans
12
Q
serpentine
A
jade-like material with elevated concentrations of chromium, nickel, cobalt
13
Q
evolution of tolerance to serpentine
A
some plants evolved over time (natural selection) to survive in serpentine soils
14
Q
An element’s properties depend on the ____.
A
structure of its atoms.
15
Q
atom
A
smallest unit of matter that still retains properties of an element
16
Q
subatomic particles
A
make up atoms
neutron, proton (+), electron (-)
17
Q
atomic nucleus
A
dense core made of protons and neutrons, surrounded by cloud of electrons (attracted by charge)
18
Q
mass of proton/neutron
A
1.7 x 10^-24 g/1 Dalton
19
Q
dalton
A
unit of measurement same as 1 amu
20
Q
atomic number
A
number of protons of a certain element
written in subscript on the left of the symbol
usually indicates number of electrons as well, IF atom isn’t an ion
21
Q
mass number
A
sum of protons + neutrons
superscript to the left of the symbol
22
Q
atomic mass
A
total mass of an atom
23
Q
isotopes
A
different atomic forms of the same element, with different neutron number
have greater masses
24
Q
radioactive isotope
A
unstable, nucleus decays spontaneously, gives off particles and energy
25
radioactive tracers
radioactive atoms put into bloodstream to diagnose certain disorders (eg. kidney disease)
26
PET scanners
monitor growth and metabolism of cancers in the body
27
dangers of decaying isotopes
radioactive fallout
| severity depends on amount/type of radiation
28
radiometric dating
used to date fossils
| measure ratio of different isotopes and calculate how many half-lives have passed since an organism was fossilized
29
half-life
parent isotope decays into daughter isotope
| amount of time for 50% of parent to decay
30
Which subatomic particles are responsible for chem reactions?
electrons
31
energy
capacity to cause change (eg. by doing work)
32
potential energy (PE)
energy matter possesses b/c of its location/structure
33
What is matter's natural tendency?
to move towards the lowest possible state of potential energy
34
Skills Exercise: Neanderthal Extinction
- used carbon-14 dating to determine age of Neanderthal fossil from most recent layer
- half-life of carbon-14 is 5,730 years
- fossil had ~ 0.0078 as much carbon-14 as the atmosphere
35
potential energy of an electron is from:
- their distance from the nucleus; the more distant an electron is from the nucleus, the greater the potential energy
- energy level; can't exist between energy levels, only at certain ones
36
electron shells
have characteristic average distance and energy level
where electors are found
represented by concentric circles
first shell = closest to nucleus (lowest PE)
contain electrons at a particular energy level
37
Can electrons move between shells? How?
Yes, but only by absorbing/losing amount of energy equal to the difference in PE between its position in the old and new shell
38
When an electron absorbs energy:
it moves to a shell further from the nucleus
39
When an electron "falls back" to a shell:
the lost energy is released into the enviro as heat
40
Chemical behavior of an atom is determined by the:
distribution of electrons in the electron shells
41
How many electrons can the first shell hold?
2 electrons
42
How many electrons can the second, third, etc shells hold?
8 electrons
43
The outermost shell determines:
the chemical behavior of an atom, based on the NUMBER of electrons in it
44
valence shell/valence electrons
the outermost shell and outermost electrons
| unpaired electrons react
45
Atoms with full valence shells will:
not react w/ other atoms; inert
46
Each concentric circle in a 2D drawing:
represents only the average distance between an electron in that shell and then nucleus
47
orbital
3D space where an electron is found 90% of the time
component of an electron shell
no more than 2 electrons can occupy a single orbital
4 orbitals of the second electron shell = up to 8 electrons
48
types of orbitals
1st electron shell: only one spherical s orbital (1s)
| 2nd electron shell: 4 orbitals, 1 large spherical s orbital (2s), 3 dumbbell-shapped p-orbital (2p orbitals)
49
Formation and function of molecules depend on ____ between ___
chemical bonding, atoms.
50
chemical bonds
attractions between atoms that interact
51
covalent bonds
sharing of a pair of valence electrons by 2 atoms
52
molecule
2+ atoms held togeterh by covalent bonds
53
molecular formula
indicates how many atoms in the molecule (eg. H2)
54
Lewis Dot structure
element symbols are surrounded by dots that represent the valence electrons (eg. H:H)
55
structural formula
line represents single bond; double bond is two lines (eg. H-H, or O=O)
56
valence
bonding capacity of an atom corresponding to # of covalent bonds they can form; equals # of unpaired electrons required to complete the atom's outermost shell
57
electronegativity
attraction of a particular atom for the electrons of a covalent bond; more electronegative = more strongly it pulls shared electrons toward itself
58
nonpolar covalent bond
electron is shared equally between 2 atoms; same electronegativity
59
polar covalent bond
electron not shared equally b/c differing electronegativities (eg. water = very polar b/c oxygen is very electronegative)
60
partial negative
caused by polar covalent bonds
| indicated w/ delta signs
61
ions
two oppositely charged atoms (b/c electron stripped away from another)
applies to molecules that are electrically charged
62
cation
positively charged ion
63
anion
negatively charged ion
64
ionic bond
bond between any two oppositely charged ions (eg. sodium and chlorine)
65
ionic compounds/salts
compounds formed by ionic bonds
often found as crystals in nature
made of vast #s of cation ions and anions bound by electrical attraction and arranged in 3D lattice
*IS NOT a molecule
66
importance of weaker bonds
- two molecules can come together, respond, then separate
| eg. water and ionic bond, hydrogen bonds and van der Waals
67
hydrogen bond
attraction between a hydrogen and an electronegative atom (when covalently bonded w/ electroneg atom, has slight pos charge that allows it to be attracted to diff electroneg atom nearby)
68
van der Waals interactions
individually very weak; occur only when atoms and molecules are very close together
constantly changing regions of pos/neg charge in molecules
69
linear shape
molecule consisting of two atoms
70
Molecule shape is determined by:
position of atoms' orbitals
(eg. atoms w/ valence electrons in both s and p orbitals form 4 new hybrid orbitals shaped like teardrops from region of atomic nucleus; if connect larger ends w/ lines, have a tetrahedron)
71
importance of molecular shape
determines how biological molecules recognize and respond to one another / specificity (only bind temporarily if their shapes are complementary)
(eg. opiates, which relieve pain and alter mood by weakly binding to specific receptor mollies on brain cell surfaces; have shapes similar to endorphins)
72
Chemical reactions ___ and ____ chemical bonds.
make, break
73
chemical reactions
making/breaking of chemical bonds, leading to changes in composition of matter (eg. hydrogen and oxygen reaction forms water by breaking covalent bonds of H2 and O2 and forming new bonds for H2O)
74
reactants
starting materials, on L of equations
75
products
ending materials, on R of equations
76
In chemical reactions, matter is:
conserved. Reactions can only rearrange electrons
77
All chemical reactions are:
reversible
78
factor that affects rate of reaction
concentration of reactants; greater concentration = more collisions = more opportunities to react and form products
79
chemical equilibrium
point at which the reactions offset one another exactly
is a dynamic equilibrium (reactions still going on) w/ no net effect on reactant/product concentrations
*equilibrium does NOT mean reactants and products are equal in concentration, but that their concentrations have stabilized at a particular ratio (eg. ammonia)
80
strongest chemical bonds
ionic and covalent
81
glucose
C6H12O6
| alpha glucose vs beta glucose = reversal of H and OH on first carbon
82
fructose
C6H12O6, placement of C atoms = diff
83
glycosidic linkage
connects 2 sugar molecules, disaccharide, loses water molecule as does so --> condensation reaction, dehydration reaction
84
starch
polymer of alpha glucose molecules; energy storage in plant cells
85
glucogen
polymer of alpha molecules; differs in pattern of polymer branching; energy storage in animal cells
86
cellulose
[polymer of beta glucose; structural molecule in walls of plants, major componenet of wood
87
chitin
beta glucose molec w/ N containing group attached to ring; structural molecule in walls of fungus cells; exoskeletons
88
tryglycerides
fats and oils, 3 fatty acids attached to glycerol molecule
- fatty acids = hydrocarbons (covalently bonded C and H w/ carboxyl group (COOH) at end)
- double bond in fatty acid creates bend --> saturated fats
89
saturated fats
packed tightly, higher melting point
| -single covalent bond btwn each pair of C, each C has 2 H bonded to it (saturated w/ H)
90
unsaturated fats
- liquid at room temp
| - lower melt temp
91
monounsaturated fatty acid
1 double covalent bond, each of 2 C in bond has only 1 H bonded to it
92
polyunsaturated fatty acid
2+ double covalent bonds
93
phospholipid
looks like triglyceride
| -one of fatty acid chains replaced by phosphate group
