BIO 101 Chapter Notes - Chapter 1-3: Mass Number, Atomic Number, Inductive Reasoning
4 Nov 2016
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Chapters 1-3 Review
• Characteristics of Life:
o Ability to grow
o Ability to reproduce
o Ability to respond to stimuli
• Evolution – the process by which organisms descended from preexisting
forms (chimpanzees → humans)
• Natural Selection – a natural process that underlies evolution, explaining that
individuals with certain inherited traits survive and reproduce better than
others in a different environment (organisms that overcome environmental
challenges will leave the most offspring)
• Cells = smallest unit of life
• Scientific Method:
1. Observation
2. Question
3. Hypothesis
4. Prediction
5. Experiment
6. Conclusion
• Scientific Theory:
o They have been repeatedly tested
o They involve both inductive and deductive reasoning
o They can potentially be disproven
• An atom is the smallest unit of an element
• Number of Protons = atomic number
• Number of Electrons = same as number of protons
• Atomic Number = number protons = number electrons
• Mass number = number protons + number neutrons
• Number of Neutrons = mass number – atomic number
o Example:
# Protons: 12
# Electrons: 12
Atomic #: 12
Mass #: 24.305
# Neutrons: 12
• Atoms are considered electrically neutral because protons are positive and
electrons are negative – equal number of each makes it neutral
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Chapters 1-3 Review
• Electrons are found in the outer shell (P & N in nucleus)
• Always 2 electrons in first shell, 8 in second shell, 3rd shell holds the rest (up
to 8) → add shells of 8 until all electrons are placed
• Polar Covalent Bonds – electrons are shared unequally between atoms
• Ionic bonds – an electron is transferred between atoms
• Hydrogen bonds – attractions between polar molecules in which the slightly
positive hydrogen is attracted to the slightly negative oxygen or nitrogen
• Non-polar covalent – electrons are shared equally between atoms
• Examples:
o Polar: H20, O-H, N-H
o Nonpolar: N-N, C-H, H-H
• Hydrogen Bonds – inter (between molecules), requires presence of polar-
covalent within
• Polar Covalent – unequal sharing (electrons will always spend more time
towards more electronegative atom), intra relationship (within molecules),
stronger
• Water Soluble Molecules: dissolves in water, hydrophilic, polar (ex: salt)
• Water Insoluble Molecules: doesn’t dissolve in water, hydrophobic, non-polar
(ex: fat)
• Acid, Base, Neutral
o Examples:
▪ pH = 7 → neutral
▪ H+ > OH- → acidic (hydrogen ions = acidic, H+ = acidic)
▪ pH = 2 → acidic
▪ OH- > H+ → basic
▪ pH = 14 → basic
• Organic molecule → a molecule with a carbon skeleton bonded to hydrogen
• Dehydration synthesis – formation of something, removing H2O
• Hydrolysis – the splitting of a polymer into a monomer by adding water
• Carbohydrate
o Made up of carbon, hydrogen and oxygen
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