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CH. 2: Chemical Context of Life - Coggle Diagram
CH. 2: Chemical Context of Life
Matter
Elements
Cannot be broken down by chemical reactions
Trace elements
Required (minute amounts)
Example: Fe (iron) required by all life
Example: I (iodine) essential in vertebrates
Essential elements: necessary for life
Number varies
Plants: 17
Humans: 25
O, C, H, N = ~96% of living matter
Compounds
Made of 2+ different elements
Example of emergent properties
Different characteristics than its elements
Fixed ratio of elements
Example: NaCl (1:1 ratio)
Structure of Atoms
Protons
Positive Charge
1 AMU
Found in nucleus
Determines element
Stays constant
Example: Carbon always has 6 protons (atomic number)
Electrons
Negligible mass
Outside nucleus (shells/orbitals)
Outer shell = Valence electrons
Determines chemical behavior
Examples
H covalently bonds to itself via sharing valence electrons
H ionically bonds by giving up valence electron
Orbitals = 3D space ("clouds")
Electron shells = energy levels
Negative Charge
Neutrons
Neutral Charge
1 AMU
Found in nucleus
Determines isotope
Radioactive isotopes
nucleus decays spontaneously
Used to date objects
half-life
time taken to decay 50%
radiometric dating
analyzes half-lives
Atomic Number and Mass
Atomic Number
Number of protons
Atomic Mass
Measured in Daltons (dalton = amu)
Mass number = protons + neutrons
Neutrons = mass number - protons
Atomic mass = Average of isotopes
Chemical Bonds
Form when valence shells are filled
Up to 2 electrons per orbital
Molecule shape determined by orbital positions
Molecule shape determines interactions/responses
Example: opiates with endorphin receptors
Types
Hydrogen
Hydrogen + electronegative atom
Atom = partial negative charge
H = partial positive charge
Covalent
Electrons are shared (single, double, triple pairs)
polar covalent = when electonegativity unequal
Van der Waals
between oppositely charged molecule regions
weakest bond
Example: how geckos stick to walls
Ionic
Electron transfer creates bond
Ions = when atom gains/loses electrons
Cations: positively charged
Anions: Negatively charged
Chemical Reactions
Parts
Reactants
starting materials
can be on left or right
Look at arrow to identify
Products
resulting materials
can be on left or right
Look at arrow to identify
Types of Reactions
Decomposition
AB = A + B
Reactants break to form products
Displacement
Single
AB + C = AC + B
Double
AB + CD = AD + BC
Synthesis
A + B = AB
Reactants combine to form product
Properties
Chemical Equilibrium
Reactions offset each other at same rate
Specific ratio, not equal concentration