8/28 - Lecture Notes PDF

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Lecture Notes 8/28 Origin of Species (1859): Descent with modification with natural selection behind it. Darwin said: ○ Organisms in a population vary in traits ○ Traits are heritable ○ Competition is inevitable ○ Species adapt to their environment ○ offspring are produced > offspring who survive Example: Peppered Moths = Due to pollution, predators hunted the more visible type of species, which let the other species reproduce. Darwin said that natural selection can cause ancestors to have more than one descendent species. Adaptations = evidence for evolution ○ Example: bat’s wings Evolution causes biodiversity Two types of scientific inquiry: ○ Discovery science: natural structures and processes. Based on observation and analysis of data. ○ Hypothesis-based science: lead to predictions tested by observation and data. Theory: ○ Broader than hypothesis, general, supported by large body of hypothesis, leads to new hypotheses. Molecules = 3D objects, computer, equations, diagram Biology leads to discoveries, technology to inventions ○ 3 domains of life ○ Ds, HBS, Q+Q data Chapter 2

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Theme: life occurs in water. Electrons stay closer to Oxygen because it’s a polar molecule. When you see bugs skating on top of water, cohesion and adhesion are at work.

Isotopes ● Atoms of an element that differ in # of neutrons ● Radioactive isotopes give off energy and particles ● Compound has different traits than just the elements that make it up. ○

Ex: Table salt (NaCl) has ionic bonds

Essential Elements ● Oxygen (O), Carbon (C), Hydrogen (H), and Nitrogen (N) make up for 96% of the body.

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Calcium (Ca), Phosphorus (P), Potassium (K), Sulfur (S), Chloride (Cl), and Magnesium (Mg) make up for 4% of the body. Boron, Chromium, Copper, Fluorine, Iodine (I) make up for 0.4% of the body. Atomic Number is the number of protons for an element. Mass Number is the sum of protons and neutrons for an element.

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Atomic mass is mass of atom. Energy is the capacity to create a charge.

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Potential energy is affected by the location of the atom.

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Chemical energy found in bonds are determined by electrons in electron shells. ○ Carbon (C) is a perfect molecule because it has 4 valence electrons. Octet rule = 8 valence electrons. Water is an inert molecule. Molecules can share, give, or gain their electrons, which can make them more stable.

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Bonds ● Covalent ○ Example: water (H2O) and carbon dioxide (CO2) ● Ionic

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○ Example: table salt (NaCl) Hydrogen ○ Example: water (H2O) Bond Strength Hierarchy: Covalent > Ionic > Hydrogen Atom with partially full shell

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○ Oxygen has 6 electrons and Hydrogen has 1, which causes sharing to occur. One covalent bond means that one pair of valence electrons are being shared. A double covalent bond means that two pairs of valence electrons are being shared.

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