BIOL 1107 1nd EditionFinal Exam Study GuideEach section below includes material from the lecture, homework and textbook. Test 1Chapter 2: The Chemical Context of Life (2.1 & 2.2) Matter + Elements properties & atoms- Organisms are composed of matter, which is anything that takes up space and has mass- Matter = made up of elements. Element = substance that cannot be broken down- Compound: substance consisting of two or more different elements combined in afixed ratio. A compound has different characteristics than the elements that make it - Of 92 elements that exist today, 20-25% are essential elements that organisms need to live and reproduce - Oxygen (O), carbon (C), hydrogen (H) and nitrogen (N) make up 96% of living organisms. Calcium (Ca), phosphorous (P), potassium (K), sulfur (S) and a few others make up most of the rest. - Trace elements: only required in small amounts in organisms. - An element is defined by the number of protons it has, but some elements have different numbers of neutrons. These different extreme forms are called isotopes. - Atoms are mostly empty space. An atom’s electrons possess energy. Energy is defined as the capacity to cause change (through work). Potential energy is the energy that matter possess because of its location or structure. - Matter has a tendency to move to the lowest point/ state of potential energy. Electrons have potential energy. The more distant an electron is from the nucleus, the greater its potential energy. An electron’s potential energy is determined by its energy level. - An electron cannot exist between energy levels. They are found in electron shells. When an electron absorbs energy, it moves away from the nucleus - The chemical behavior of an atom is determined by the distribution of electrons. Electrons tend to exist in the lowest available state of potential energy. However, the first shell only holds 2 electrons. (2.3) Chemical bonding and molecules - Atoms either share or transfer valence electrons. This sharing or transferring created chemical bonds. The two strongest are covalent and ionic. - A covalent bond is the sharing of a pair of valence electrons between 2 atoms. Two or more atoms held together by a covalent bond creates a molecule. - There are two ways to represent a molecule structure: Lewis dot structure orstructural formula. In a structural formula, a straight line represents a singlebond. Two pairs of shared electrons create a double bond. - An atom’s valence is its bonding capacity (equals the number of unpairedelectrons). Atoms share electrons to a varying degree. - Attraction of electrons to a covalent bond is electronegativity. Greaterelectronegativity means a greater attraction/pull to electrons. In a covalent bondwhere electrons are shared equally, the bond is nonpolar. However, whenbonding elements have different electronegativities the bond is polar. - In some elements, the electronegativity difference is so great, electrons aretransferred rather than shared. This creates net electrical charges. A chargedatom/molecule is called an ion. When an ion is positive, it is a cation. A negativeion is called an anion. The bond formed between the two is an ionic bond.Compounds formed by ionic bonds are ionic compounds or salts. - Besides covalent and ionic bonding, there are also weaker bonds and attractions.One of which is the hydrogen bond. It is a noncovalent attraction betweenhydrogen and an electronegative atom. There are also van der Waalsinteractions which are caused by distortions in the electron cloud. These areusually very weak. Chapter 3: Water and Life(3.1) Polar bonds, water and hydrogen bonding -Water’s unique behavior can be traced to its structure and interactions. -It has polar covalent bonds because oxygen is more electronegative. This makesthis molecule polar. (because the overall charge is unequally distributed)-Water molecules can also hydrogen bond with each other (up to 4 H bonds). Hydrogen bonds are very fragile, about 1/20 as strong as a covalent bond. They form and break very easily. They last very shortly but new ones form very quickly. A lot of qualities of water are due to hydrogen bonding. (3.2) Four emergent properties of water - 4 properties: cohesion behavior, ability to moderate temperature, expansion upon freezing, and versatility as a solvent.- Water molecules stay close to each other due to H bonding. These kinks make water more structured than most other liquids. Collectively H bonds hold a substance together through cohesion. This contributes to the transport of water and dissolved nutrients against gravity.- Water from the roots reaches leaves through water-conducting cells. As water evaporates from the leaves, H bonds cause it to tug on molecules further down and pull upward. - Adhesion is the clinging of one substance to another, also plays a role. Adhesion helps counter gravity. - Related to cohesion is surface tension (measure of how difficult it is to stretch or break surface of a liquid). Water has a greater surface tension than most liquids.- Anything that moves has kinetic energy (KE), energy of motion. Faster a molecule moves, greater its KE. - Heat: form of energy. The amount of heat is a measure of matter’s total kinetic energy. Heat also depends on volume (of the matter). Heat and temperature -> not the same thing.- Temperature: measure of heat intensity that represents the average KE of molecules, regardless of volume. Whenever two objects of different temps are brought together, heat passes from the warmer object to the cooler one. KE of cooler object increases.- Water is less dense frozen (ice floats). Water expands instead of contracting when it freezes. This is because of hydrogen bonding. Due to the cold when water freezes, it gets locked into a crystal lattice. - A liquid that is completely homogenous of 2 or more substances is a solution. Thedissolving agent is the solvent. A dissolved substance is the solute. An aqueous solution is one where water is the solvent. - A substance that has an affinity for water is said to be hydrophilic. Some substances are hydrophobic but do not dissolve in water. They end up suspendedin the water. These are colloids (stable suspension of fine particles in a liquid). Some non-ionic and nonpolar