SCIENCE AND CHEMISTRY L2 Flashcards
I. Themes in biology - CC, SEQ levels of organization II. Methods of investigating biology - SEQ process of science III. Basic elements of chemistry - CC chemical bonds IV. Emergent properties of water - CC properties of water
1
Q
evolution
A
- unifying idea of biology
- all living organisms are modified descendants of common ancestors
2
Q
emergent properties
A
- properties result from arrangement and interaction of parts within a system
- ex. bike, assembled v. dissembled
3
Q
the scientific method
A
- finding natural explanations for natural phenomena
- limited to observable and measurable structures and processes
4
Q
hypothesis
A
- testable proposed explanation for observations based on available data
5
Q
prediction
A
- expected outcome when you test a hypothesis
6
Q
theory
A
- broad explanation with significant support, leads to new hypotheses and accurate predictions
- ex. earth revolves around sun
7
Q
law
A
- statement of what always occurs under certain circumstances
- observable pattern
- not explanatory
- ex. conservation of energy
8
Q
electrons
A
- atoms made of protons, neutrons, and electrons
- subatomic particles
- 1 unit of negative charge
- move rapidly around atomic nucleus
9
Q
potential energy
A
- energy that a material possesses due to its location or structure
- can be used to do work
- capacity to cause change
- once used, work has to be done to restore
10
Q
electrons and energy
A
- electrons located in distinct shells
- have potential energy due to distance from nucleus
- further from nucleus = higher energy
- absorb energy to move to higher shell
- release energy when they fall to lower shell
11
Q
valence electrons
A
- valence shell: outermost shell
- valence electrons: occupy valence shell
- H and He have up to 2 electrons in valence shell
- everything else has up to 8 electrons in valence shell
12
Q
formation of molecules
A
- compound of 2 or more atoms held together by chemical bonds
13
Q
chemical bonds
A
- result of how atoms share electrons
- want a full valence shell
- will share, donate, and accept electrons to achieve
- energy stored in chemical bonds
14
Q
electronegativity
A
- measure of atoms affinity for electrons in chemical bonds
- atoms in a molecule attract electrons to varying degrees
- more electronegative = more strongly pulls electron towards itself
15
Q
covalent bond
A
- sharing electrons between atoms
- results in a full valence shell for each
- strongest type of bond under biological conditions
16
Q
non polar covalent bonds
A
- same or similar electronegativity
- electrons shared equally
- shape could prevent polarity
17
Q
polar covalent bonds
A
- unequal electronegativity
- unequal electron sharing
- causes partial + or - charges
18
Q
ionic bonds
A
- highly unequal electronegativity
- electrons lost or gained
- ion: charged atom
- like charges repel, opposites attract
- bond formed by attraction between anion and cation
19
Q
salts
A
- compound formed by ionic bonds
- dissolve in water
20
Q
van der Waals interactions
A
- relatively short lived, relatively weak interactions due to electron position and motion
- areas with partial + and - charges interact
- strong in large numbers
- includes many different interactions: London dispersion, hydrogen bonds
21
Q
hydrogen bonds
A
- type of van Der Waals
- partial charges result when H combines with electronegative atom (F, O, N)
- partial positive charge on H tends to associate with partial negative charge on electronegative atom
- resulting interaction is called a hydrogen bond
- water is a polar molecule due to polar covalent bonds
- forms H bonds with each other
- constantly broken and reformed
- responsible for many important properties
22
Q
cohesive behavior
A
- cohesion: water molecules stick to each other
- surface tension: measure of how difficult it is to stretch or break the surface of a liquid
23
Q
adhesion
A
- water molecules can also be attracted to other things
- ex. water transport in plants
- capillary action: the tendency of water to rise against gravity
24
Q
moderates temperature
A
- high specific heat: the amount of heat that must be absorbed to raise 1g of substance 1 degree C
- raising temperature = adding energy; molecules move faster = bonds have to break
- H bonds in water resist faster movement of molecules
- takes a lot of energy to change temperature of water
- ex. climate, body temperature via evaporative cooling
25
Q
expansion upon freezing
A
- liquid water- 15% of molecules have 4 H bonds
- ice: all have 4 H bonds
- ice is less dense than liquid water
- prevents bodies of water from freezing from the bottom up
26
Q
versatility as a solvent
A
- hydrophilic: substances have an affinity for water, will dissolve, partial positive and negative regions, can form H bond with water
- hydrophobic: substances have no affinity for water, nonpolar, nonionic, cannot form H bonds, ex. oils
