BIO 101 Chapter 2: Fundamental Building Blocks, Chemistry, Water, and pH
BIO 101 Chapter 2: Fundamental Building Blocks, Chemistry, Water, and pH BIO 101
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This 7 page Class Notes was uploaded by Natalie Berry on Sunday September 11, 2016. The Class Notes belongs to BIO 101 at Missouri State University taught by Kyoungtae Kim in Fall 2016. Since its upload, it has received 39 views. For similar materials see Biology in Your World in Science at Missouri State University.
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Date Created: 09/11/16
Key: Light Blue = main idea Purple = important parts of the main idea Green = examples Orange = key terms Pink = the definition of the key term Red = especially important Bio 101: Fundamental Building Blocks: Chemistry, Water, and pH Chemistry’s building block: the atom Everything that exists falls into one of two categories: matter or energy Matter and its transformations is the subject of chemistry Matter: anything that takes up space and has mass Mass: a measure of the quantity of matter in any given object Things that define mass: How much space does an object occupy? (volume) How dense is the matter within the space? In biology think of mass as equivalent to weight What is matter? Plato said all matter is made up of 4 primary substances: earth, air, fire, and water (I remember this part as the Avatar haha) Democritus believed that those substances were made of smaller units that were invisible and indivisible – atoms Matter is composed of atoms that are “invisible” to the human eye but can be divided Protons, Neutrons, and Electrons The 3 parts of an atom are protons, neutrons, and electrons These 3 parts exist in a special assignment that is always the same Protons and neutrons are packed tightly around the atom’s nucleus and electrons move around it at a certain distance proton (positive charge) -e neutron (no charge) electron shell electron (negative charge) -e Key: Light Blue = main idea Purple = important parts of the main idea Green = examples Orange = key terms Pink = the definition of the key term Red = especially important The nucleus takes up little space of the atom, but accounts for most of its mass The whole atom is electrically neutral The # of protons is exactly equal to the # of electrons, # of neutrons varies Fundamental Forms of Matter Element: a substance that is “pure” in that it cannot be reduced to a different component Ex. Gold The number of protons in an atom’s nucleus define each element Atomic number: the number of protons in an element’s nuclei Isotopes Atoms have neutrons in their nuclei, these add weight to the atom The number pf neutrons vary from the # of protons Isotopes – a form of an element as defined by the # of neutrons contained in its nucleus. Different isotopes of an element have the same # of protons but differing #s of neutrons Chemical Bonding: the Covalent Bond Chemical bonding: the process of chemical combination and rearrangement Covalent bonds: when two atoms share the outermost electrons Ionic bonds: when an atoms give up an electron Energy always seeks its lowest state With electrons, the energy is not gravitational but electrical Atoms undertake bonding because it’s a more stable option Atoms want to be in a lower energy state because its more stable Atoms achieve this lower state by filling their outer shells Seeking a full outer shell: covalent bonding Electrons live in a certain well-defined “energy levels” outside the nuclei of atoms called outer shells The number of energy levels depend on the element Two electrons are required to fill the first shell of any atom Eight are required to fill all the shells after in most elements Chemical bonding in water H20 - 2 hydrogens atoms combine with 1 oxygen atom Consider: 1. Hydrogen has only one electron orbiting its single shell 2. The only way a 1 shell is completed is if it has two Key: Light Blue = main idea Purple = important parts of the main idea Green = examples Orange = key terms Pink = the definition of the key term Red = especially important 3. The oxygen atom has eight electrons, it needs 2 to complete its other shell 4. In conclusion, oxygen needs and welcomes a partner Covalent bonds e e e e e e e e e e When the pairing of electrons happens, no matter is gained or loss This is the law of conservation of mass: no matter is created or destroyed in a chemical reaction What is a molecule? Molecule – when 2 or more atoms combine in a covalent reaction A defined # of atoms covalently bonded together A molecule doesn’t need to be made of two different elements A molecule can also contain many different elements bounded together Reactive and Unreactive elements Not all elements have incomplete outer shells Ex. Helium has two electrons meaning it is extremely unreactive There are also reactive elements Key: Light Blue = main idea Purple = important parts of the main idea Green = examples Orange = key terms Pink = the definition of the key term Red = especially important Ex. Sodium has 11 electrons. 2 on the first and 8 on the outer. This leaves one on the third shell making it very unstable Between reactive and unreactive are elements with a range of outer electrons (or valence) The spectrum of stability for chemical elements is 1-8 and is based on the number of outer shell electrons each element has One is the most reactive and eight is the least reactive Covalent polar and non-covalent polar bonding Not all covalent bonds are created alike Ex. The hydrogen bond (H2) electrons are shared equally, this isn’t the case with water molecules Electronegativity – when an atom has greater power to attract electrons to itself In a water molecule since an oxygen atom has more electronegativity than a hydrogen atom, it pulls shared electrons away from hydrogen to itself The above is called polarity – a difference in electrical charge at one end Polar covalent bond – a covalent bond where electrons are shared unequally between atoms, the one end of the molecule has a slight - charge and the other end has a slight + charge Non-polar covalent bonds – a covalent bond where electrons are shared equally It is possible for atoms with different electronegativity to link and have a non-polar molecule Ex. Water is polar because oxygen ( that has more electronegativity) lies on one side of the two hydro atoms The Ionic Bond Ion: a charged atom, or an atom whose # of electrons differs from the # of protons Ionized forms of atoms are written like so: if an atom gains or loses Mg²+ let’s say this magnesium atom loses two electrons electrons a # would be put before the charge sign Key: Light Blue = main idea Purple = important parts of the main idea Green = examples Orange = key terms Pink = the definition of the key term Red = especially important ionic bonding: a chemical bond where 2 ions are linked by their opposite charge this hardly ever happens with just 2 ions ionic compound: a collection of the atoms of two or more elements that have linked from ionic bonding this is compound is NOT a molecule; it does not have a defined number of atoms the atoms that do make it up are linked through ionic bonds, not covalent Hydrogen Bond Hydrogen bond: links an already covalently bonded hydrogen atom with an electronegative atom (ex. Oxygen) Hydrogen bond nearly always pair hydrogen with either oxygen or nitrogen These bonds are important in DNA and proteins These bonds are weak compared to ionic and covalent bonds, they are constantly breaking and shifting Three dimensional shape in molecules The molecules and ionic compounds are three dimensional like a sculpture They can be in a row, a triangle, or a pyramid shape Molecular shape matters because it determines the capacity of molecules to latch on to one another Ex. When you smell an aroma, the gas molecules bond with the receptors in your nose sending a message in your brain what the smell is; it’s the shape of the molecule that binds the two Water and Life Life and water have been intertwined over time Life began and only existed in water for 3 billion years before living things came to land (11% of earth’s history) Organisms could not have come to land without bringing water “with them”; inside their bodies 66% of the human body is water, most vertebrae animals have 70 or 80 percent, and plants have 90% Living things cannot be fully functional without water Water plays a major role in many of life’s processes Water is a medium where the series of chemical reactions that are life take place Key: Light Blue = main idea Purple = important parts of the main idea Green = examples Orange = key terms Pink = the definition of the key term Red = especially important Life’s chemicals take better place in water, since liquid allows better distribution of materials Water facilitates these reactions because of its chemical structure Solution: a mixture of two or more kinds of molecules, atoms, or ions that is homogenous uniform throughout Ex. Mixing salt and water Solute: what is being dissolved Ex. Salt Solvent: what is doing the dissolving Ex. Water Water’s unusual properties: Moderating Temp Water serves as an insulator when it’s frozen, liquid, and gas This is due to specific heat, the amount of energy required to raise the temp of a substance Water has the ability to release heat when the environment around it is colder than itself The ocean absorbs the sun’s energy and releases its heat when the air above it gets colder These are because of hydrogen bonds Heat is the motion of molecules To move chemical bonds, they must first be broken = hydrogen bonds Cohesion and surface tension Cohesion: the tendency of water molecules to stay together Because of this evaporation can work with osmosis to draw water from roots to a plant’s leaves and to the air as vapor Acid and Bases The way to measure the degree to which something is acidic or basic is the pH scale Power pH hydrogen Acid: any substance that produces hydrogen ions when put in a water based solution Base: any solution that accepts hydrogen ions in water based solutions pH scale: a scale used to measure the acidity of substance the lower numbers are the most acidic as a solution becomes more basic, the pH rises Key: Light Blue = main idea Purple = important parts of the main idea Green = examples Orange = key terms Pink = the definition of the key term Red = especially important a solution that is basic is considered an alkaline solution since hydrogen has 1 proton, that means acid yields protons while a base accepts them Why pH matters Generally, it’s because living things are sensitive to the different levels Enzymes and cell membranes can start to break down if something is too acidic Enzymes have to maintain a certain shape, if the shape is affected it cannot function If these two are interfered with it can result in death Many organisms have developed an acid-base “buffering systems” Physiological systems that function to keep pH within normal limits Usual range for living things is 6-8 Human cells have a limit of 7 and the blood in our arteries is about 7.4 Different parts of the body have different pH requirements Ex. The interior of our stomach can have pH as low as 1 pH can also affect entire communities Ex. Acid rain, which is caused by air pollution, affects forests, streams and lakes
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