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SC BIOL 101 - Biology Chapter 2 Lecture Notes

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Atom molecule and life cont.Chapter 3 WaterBiology Chapter 2: Atoms, Molecules, and Life- Energy-the capacity to do work1. kinetic-involves motion 2. potential-stored form of energy that mass may possess due to its position- Matter-anything that takes up space or has mass; made up of elements (cannot be broken down into other substances by ordinary chemical means) and compounds ***Table 2.2 Elements in the human body- Atomo Number of protons is equal to the number of electronso Has a dense core called the nucleus which contains protons and neutronso Protons-positive and are 1 AMU (atomic mass unit)o Neutron-neutral and are also 1 AMU (atomic mass unit)o Surrounding the nucleus are electronso Ions-are atoms that have either an extra electron or lost an electrono Molecules can be ions; made with atoms joined together with covalentbondo Atomic number-refers to the number of protons in an atomo Atomic mass (weight)-number of protons plus number of neutrons; measured in AMUso Isotopes-atoms with an unusual number of neutronso Radioisotopes-unstable isotope; radioactive; used to treat cancers- Electron Stability and Chemical Bondso Electron shells-level around the nucleus; k(2), L(8), m(8)o Electron orbitals-within the shells- Atoms want to achieve stability 1. electrons get as close to the nucleus as possible2. have a completely full valence shell (outermost shell of an atom that contains electrons)-done by forming chemical bondso Noble gases don’t form chemical bonds because valence fullo Valence number-number of electrons an atom needs to fill valence shell- Chemical Bonds1. Covalent-involve sharing electron pairs2. Polar Covalent-involves un-equal sharing of electron pairs3. Ionic-electron transfer ex. NaCl- Electronegativity-atoms ability to attract electronsAtom molecule and life cont.- Covalent bonds- involve electron sharing. A pair of atoms share a pair of electrons- Molecule- a molecule is two or more atoms joined together by covalent bonds- Hydrogen- 1 covalent bond- Carbon- 4 covalent bonds- Oxygen- 2 covalent bonds- Nitrogen- 3 covalent bonds- Sulfur- 2 covalent bonds- Polar covalent bonds- when two atoms unequally share a pair of electrons. One atom is quite electronegative and the other atom isn’t very electronegativeo If oxygen or nitrogen is bonded to anything besides each other that will be a polar covalent bondo The charged end of a PC bond are often indicated by the greek letter delta- Ionic bonds- involve an electron transfer. They are not shared as in covalent bonds. Once the electron transfer happens there is an electrostatic attraction between the ions. Compounds are produced as a result of ionic bonds. Ionic bonds are very strong and stable in dry air. But in water they will dissolve. o Salt is a compound but not a molecule- Hydrogen bond- is when a hydrogen nucleus, which is the same thing as a proton is shared by two electromagnetic atoms Covalent bonds= a solid line Hydrogen bond= dotso Hydrogen bonds are incredibly weak Chapter 3 Water- The only substance that can exist in all three forms of matter at the same timein the same place- Water is what makes life possible- Water forms hydrogen bonds - cohesion- water molecules stick together because they form hydrogen bondso This is important to plants, because water molecules stick together to form a tube from the roots to the plant- Adhesion- water will stick to molecules of living things by forming hydrogen bonds- Mediation of temperature- o Heat is the measure of the kinetic energy of mattero Temperature is a measure of heato Calorie- the amount of heat necessary to raise the temperature of 1 gram of water mlo Specific heat of water- 1 calorie. Alcohol .6 calorie. Iron .1 calorieo It takes more heat to raise the temperature of water because it has a higher specific heat, requiring more kinetic energy- Water moderates our climate and keeps the temperature stable- Ice- water gets less dense as it freezes than when it is a liquid. This means that ice floats. It floats because in liquid water there is still enough heat to break some hydrogen bonds. Therefore the water is - denser. - Surface tension- at the surface water molecules stick together with hydrogen bonds. - Evaporative cooling- when water evaporates it takes a lot of energy to changethe water from a liquid to a gas. Therefore it feels cool. In order to do that youhave to break all of the hydrogen bonds that are holding the water to your skin- Water is the solvent of life. Meaning many ions and compounds that we need are dissolved in the water in our body. Water is sometimes referred to as the universal solvent because it can dissolve almost anythingo Solution- solutes dissolved in a liquid (the solvent) (homogenous mixture)o Aqueous solution (water=solvent)o Solutes can be dissolved into water- Hydrophilic- water loving- Hydrophobic- water fearing- “like dissolves like”- Water- polar substance-dissolves polar substanceso Polar substance will dissolve polar solutes; lots of oxygen or nitrogen ex. ethanol glucoseo Non-polar- ex. fats and oils; water wont dissolve; very little oxygen - Hydration sphere- Hydration shell-ex. table salt (how water dissolves)- Soaps and detergents are examples of amphipathic molecules (both polar andnon-polar)- Colloid-a suspension of fine particles in a liquid ex. blood-rbcs are suspended in solution- Molarity=Mo 1 molar solution of glucoseo Atomic mass-mass of atom; p+n; measured in Daltons or amuso Molecular mass-mass of molecules; glucose=C6H1206=180 Daltons (sum of atomic masses)o Mole is the A.M or M.M in gramso Mole=6x10^23 particles (Avogadro’s #)o Solutions:-1 molar solution of glucose (180 g of glucose in beaker); 1 L of H2O- Acids, Bases, PHo Deal with protons; hydrogen nuclei; hydrogen ions=H+o Hydrogen atom (extremely reactive)o Acids-proton donors; increase proton number in a solution; ex. sulfuric acid; strong acids dissociate completely; weak acids dissociate incompletely (don’t completely break apart) ex. carbonic acido Bases-proton accepters; decrease # in a solution-ex. ammonia will grab onto protons and form ammonia ions-ex. potassium hydroxide dissociate; hydroxide forms watero pH less than 7 is acidic-move H+ than OH-; lower the pH the more acidic it is; basic more OH-; most basic is pH of 14o pH of blood ranges from 7.35-7.45; pH of 7 would be fatalo Buffers- aqueous solution consisting of a mixture of a weak acid and corresponding baseEx. carbonic acid (weak acid dissociates


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