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Elements & Atoms 2.1 Slides document so are Created by G.Baker www.thesciencequeen.net An atom refresher • Matter is anything that takes up space and has mass. • All matter is made of atoms • Atoms are the building blocks of matter, sort of how bricks are the building blocks of houses. Created by G.Baker www.thesciencequeen.net An atom refresher • An atom has three parts: • Proton = positive • Neutron = no charge • Electron = negative • The proton & neutron are found in the center of the atom, a place called the nucleus. Picture from http://education.jlab.org/qa/atom_model_03.gif • The electrons orbit the nucleus. Created by G.Baker www.thesciencequeen.net What are elements? • Elements are the alphabet to the language of molecules. • To make molecules, you must have elements. • Elements are made of atoms. While the atoms may have different weights and organization, they are all built in the same way. Information & picture from Chem4kids at http://www.chem4kids.com/files/atom_structure.html Created by G.Baker www.thesciencequeen.net Graphic from http://education.jlab.org/atomtour/fact2.html Created by G.Baker www.thesciencequeen.net More about Elements.. • Elements are the building blocks of all matter. • The periodic table is a list of all of the elements that can build matter. It’s a little like the alphabet of chemistry. • The periodic table tells us several things… Created by G.Baker www.thesciencequeen.net Periodic Table Atomic Number: Number of protons and it is also the number of electrons in an atom of an Element’s Symbol: element. An abbreviation for the element. Elements Name 8 O Oxygen Atomic Mass/Weight: Number of protons + neutrons. Created by G.Baker www.thesciencequeen.net 16 • Atoms are made up of three particles: Protons Neutrons Electrons • Question: Which of the three particles identifies what element an atom is? • The PROTON! (very important) Created by G.Baker www.thesciencequeen.net Different Forms of the Same Element • In any element, the # of protons is always constant. • Unlike the number of protons, the number of electrons and neutrons can vary within an element without changing the identity of the element. Ex. Carbon (C) ALWAYS has 6 protons, but it can have anywhere from 6-8 neutrons and 2-10 electrons Created by G.Baker www.thesciencequeen.net Isotopes • An ISOTOPE is a form of an element that has a different number of neutrons than “normal” • Carbon has three isotopes Atom Models • There are several models of the atoms, we will be using one in class. • Lewis Dot Structure Electrons have special rules…. • You can’t just shove all of the electrons into the first orbit of an electron. • Electrons live in something called shells or energy levels. • Only so many can be in any certain shell. Created by G.Baker www.thesciencequeen.net Nucleus 1st shell 2nd shell 3rd shell Adapted from http://www.sciencespot.net/Media/atomsfam.pdf Created by G.Baker www.thesciencequeen.net Electrons have special rules…. • You can’t just shove all of the electrons into the first orbit of an electron. • Electrons live in something called shells or energy levels. • Only so many can be in any certain shell. • The electrons in the outer most shell of any element are called valance electrons. Created by G.Baker www.thesciencequeen.net Chemical Compounds • A chemical compound is two or more elements combined together to form a “compound” • Common compounds: Water (H2O) Salt (NaCl) • The element proportion of the compound is always the same Water is always H2O regardless if it is a drop or a lake of water • The compound properties are very different from those of the element used to form them Chemical Bonds • Chemical bonds are what hold elements together • There are TWO main types of chemical bonds: IONIC COVALENT Ionic Bonds • Formed when one or more electrons are transferred from one atom to another • Remember that as a whole elements are electrically neutral but if there is a movement of electrons they can become positive or negative • A charged element is called an ION Covalent Bonds • The sharing of electrons between two or more atoms • The electrons move between the nuclei of both elements in the compound • When covalent bonds are formed a molecule is formed, it is the smallest unit of a compound • Water is a covalent bond Van der Waals Force • The term given to intermolecular attraction of molecules in close proximity to one another • Water bugs So let’s try it…Lewis Dot Structures • How to draw a Lithium atom • First, look at the Periodic Table • Second, determine the number of protons (Look @ the atomic number) • Then determine the number of neutrons (Atomic mass – atomic number) • Then determine the number of electrons (Look @ the atomic number) 3 Li Lithium 7 Created by G.Baker www.thesciencequeen.net So let’s try it…. Protons = 3 3 - Li + + + Lithium - 7 Electrons = 3 2 in the 1st shell, 1 in the 2nd shell Neutrons = 4 (7-3=4) Created by G.Baker www.thesciencequeen.net Lewis Dot Structure • The Lewis Dot Structure is a bit different from the Bohr model. • It only shows the element symbol and it’s outer most electron shell. - - - + + + + - - + + + + - Created by G.Baker www.thesciencequeen.net - • • O •• •• - How to… 1. Write the symbol. 2. Start on the right hand side, working your way clockwise around the symbol. 3. Try Lithium Created by G.Baker www.thesciencequeen.net Carbon Compounds (2.3) • Carbon bonds with a variety of elements, these include: Hydrogen Oxygen Phosphorus Sulfur Nitrogen • When carbon binds with these elements many of molecules necessary for life are formed Created by G.Baker www.thesciencequeen.net Macromolecules • All organisms are composed of macromolecules • A macromolecule contains CARBON • Most macromolecules are made of smaller units (monomers) that bond to form larger molecules (polymers) • Energy is stored in the bonds that link these units together. The process of bonding and forming of macromolecules is polymerization • The amount of energy stored varies with the type of macromolecule formed. Carbohydrates • are molecules that are composed of Carbon, Hydrogen, Oxygen • Basic carbs are simple sugars (monosaccharides) such as glucose , these simple sugars can bond and create complex carbs such as starches and cellulose • Carbohydrates are the MAIN source of energy for the cell • When carbs are synthesized (created) during photosynthesis the organisms that create them use them as a source of energy or they are stored in the cells. This process usually uses monosaccharides to create polysaccharides • When carbs are consumed, digestion breaks the bond between large carbs (complex carbohydrates: polysaccharides) so that individual simple sugars can be absorbed by the blood stream through intestinal walls. Lipids • are molecules that are composed of Carbon, Hydrogen, Oxygen • Are used in a variety of ways by living organisms including: Energy storage Biological membranes Waterproof coverings • Contain two component molecules , glycerols and fatty acids so they are structurally different from carbs • Are NOT SOLUBLE IN WATER • Have more carbon-hydrogen bonds than carbs Nucleic Acids • Contain : Hydrogen, oxygen, nitrogen, carbon and phosphorus • Are polymers comprised of a monomer known as a nucleotide • Nucleotide has: 5 – carbon sugar Phosphate group Nitrogenous base • Store and transmit hereditary (genetic) information Protein • Molecules composed of chains of amino acids (a.a.) • A.A. are molecules that are composed of Carbon, Hydrogen, Oxygen, Nitrogen and occasionally Sulfer (CHONS) • There are 20 a.a. that bond to make proteins 12 a.a. are formed by the bodsy 8 a.a. must come from foods • Proteins have a variety of roles in organisms : Controlling rate of reactions Regulate cell processes Form cell structures Transport substances in and out of the cell Fight disease Created by G.Baker www.thesciencequeen.net Organizational levels of proteins • When amino acids (a.a.) are assembled the instructions come from the DNA • There are 4 levels of protein structures Primary : chain of amino acids Secondary: folding of chain Tertiary: 3-d arrangement of amino acids Quaternary: is the combination of more than one chain (hemoglobin) THE NUTRITION LABEL Easy Ways to Use the Label For Healthy Eating For more information, please contact: Food and Drug Administration Center for Food Safety and Applied Nutrition Office of Nutritional Products, Labeling, and Dietary Supplements Key Label Questions • How many calories am I actually eating? Is that number low, medium, or high? • What nutrients should I limit or get enough of and why? • What’s relevant about the footnote? • How can I tell if a %DV is high or low? • Which nutrients have no %DV? The Nutrition Facts Label One or Two Servings? Serving Size Calories Calories from Fat Total Fat Trans Fat Saturated Fat Cholesterol Sodium Total Carbohydrate Dietary Fiber Sugars Protein Vitamin A Vitamin C Calcium Iron Single Serving 1 cup (228g) 250 110 12g 1.5g 3g 30mg 470mg 31g 0g 5g 5g % DV 18% 15% 10% 20% 10% 0% 4% 2% 20% 4% Double Serving 2 cups (456g) 500 220 24g 3g 6g 60mg 940mg 62g 0g 10g 10g % DV 36% 30% 20% 40% 20% 0% 8% 4% 40% 8% General Guide to Calories* 40 Calories is low 100 Calories is moderate 400 Calories is high *Based on a 2,000-calorie diet. Limit These Nutrients The goal is to stay BELOW 100% of the DV for each of these nutrients per day. Get Enough of These Nutrients Try to get 100% of the DV for each of these nutrients each day. The Footnote Examples of DVs versus %DVs* The Percent Daily Value The % DV is based on 100% of the daily value for each nutrient. What’s High? What’s Low? Do You Have to Calculate to Know? Footnote The % DV Does the Math for You Look here for highs and lows! Quick Guide to % DV 5% DV or less is Low Limit these Nutrients Get Enough of these Nutrients 20% DV or more is High No % Daily Value • Trans Fat • Sugars • Protein Read the Nutrition Facts Label For Total Sugars Plain Yogurt Fruit Yogurt Look at the Ingredient List for Added Sugars Plain Yogurt INGREDIENTS: CULTURED PASTEURIZED GRADE A NONFAT MILK, WHEY PROTEIN CONCENTRATE, PECTIN, CARRAGEENAN. Fruit Yogurt INGREDIENTS: CULTURED GRADE A REDUCED FAT MILK, APPLES, HIGH FRUCTOSE CORN SYRUP, CINNAMON, NUTMEG, NATURAL FLAVORS, AND PECTIN. CONTAINS ACTIVE YOGURT AND L. ACIDOPHILUS CULTURES Calcium In Your Daily Diet Calcium Calcium Calculation 100% DV = 1,000mg calcium 30% DV = 300mg calcium = one cup of milk 130% DV = 1,300mg calcium = daily goal for teens For More Information www.cfsan.fda.gov/~dms/labgen.html • Guidance on How to Understand and Use the Nutrition Facts Panel on Food Labels (also available in Spanish) • Test Yourself! Test Your Food Label Knowledge! • Food Label Education Video • Calcium! Do You Get It? Properties of Water 2.2 • http://www.visionlearning.com/library/flash_viewer.php ?oid=1349&mid=55 • http://web.visionlearning.com/custom/chemistry/ani mations/CHE1.7-an-H2Obond.shtml I. Properties of Water • Single most abundant compound in living things • Liquid at the temperatures found over much of Earth’s surface • Expands as it freezes- ice is less dense than liquid water- ice floats a. The Water Molecule Overall it is neutral • Polar: molecule in which charges are unevenly distributed Protons attract electrons In a molecule the atom with more protons has a stronger hold on the electrons • Protons give them POWER • H2O: Oxygen has 8 protons Hydrogen has 1 proton Who has the POWER (the electrons)? Which end is positive? Which end is negative? • Location of Electrons: around O • Charge of O end: (-) • Charge of H end: (+) Hydrogen Bonds • One of Van der Waals Forces • Attraction between the H+ atom of one molecule and the O- atom of another molecule • Water can form 4 hydrogen bonds Cohesion • SAME substances • Why drops of water form beads. • Why insects can walk on water Adhesion • DIFFERENT substances • Why a meniscus forms in a graduated cylinder • Why water moves up against gravity in tubes and the roots of plants- Capillary Action Capillary Action • Adhesion between water and glass • Causes water to rise up a narrow tube against gravity Water rises out of the roots of a plant and up into its stems and leaves Meniscus in a graduated cylinder- water is higher next to the glass sides, water moves up the sides Mixtures Made With Water • Mixture: 2 or more elements/compounds that are physically mixed together NOT chemically • Solutions: evenly distributed throughout, dissolved in water Salt water and sugar water Solute: substance being dissolved, SALT Solvent: substance doing the dissolving, WATER Polar water can dissolve both ionic compounds and other polar molecules • Suspension: suspended in water, NOT dissolved, so small they are carried along by the water Oil and water Acids, Bases and pH • H2O↔ H+ + OH- Water ↔ hydrogen ion + hydroxide ion • pH Indicator of the concentration (amount) of H+ ions Scale ranges from 0 to 14 Each step on the scale represents a factor of 10 Neutral Acid Base Pure Water Compound that forms H+ ions in solution # of H+ > # of OH- Compound that forms OH- ions in solution # of H+ < # of OH- pH 0 to 6 pH 8 to 14 # of H+ pH 7 = # of OH- Buffers • pH of cells needs to be between 6.5 and 7.5 • Used to keep the pH at this level • Weak acids and bases • React with strong acid/bases to prevent sudden changes of pH in the body ENERGY IN REACTIONS • Energy is released or absorbed whenever chemical bonds are formed or broken. • Because chemical reactions involve breaking and forming of bonds, they involve changes in energy. CATALYST • A catalyst is a substance that speeds up the rate of a chemical reaction. • Catalyst work by lowering reaction’s activation energy. NOTICE THAT WITHOUT THE ENZYME IT TAKES A LOT MORE ENERGY FOR THE REACTION TO OCCUR. BY LOWERING THE ACTIVATION ENERGY YOU SPEED UP THE REACTION. ENZYMES • Enzymes are proteins that act as biological catalysts. • Cells use enzymes to speed up chemical reactions that take place in cells. • Enzyme speed up reactions by lowering the activation energies. • Because a particular enzyme catalyzes only one reaction, there are thousands of different enzymes in a cell catalyzing thousands of different chemical reactions NOTE Enzymes end in ase Catalase lactase ENZYMES • Enzymes provide a site where reactants can be brought together to react. • Such a site reduces the energy needed for a reaction to occur. ALL ENZYMES HAVE AN ACTIVE SITE, WHERE SUBSTRATES ARE ATTRACTED TO. • Enzymes are used over and over again. SUBSTRATE • The substance changed or acted upon by an enzyme is the substrate. THE ENZYME SUBSTRATE COMPLEX • When enzymes function the active site interacts with the substrate. • The active site shape matches the substrates shape. (like a lock and key) • Once the substrate and active site meet a change in shape of the active site causes a stress that changes the substrate and produces an end product. WHICH ONE WILL FIT ? WHY ENZYMES? • http://www.youtube.com/watch?v=XTUm-75PL4&feature=related THE FACTORS THAT AFFECT ENZYME ACTIVITY ARE • pH • Temperature • Amount of substrate AFFECTS OF TEMPERATURE ON AN ENZYME • If temp to high or to low the enzyme will not fit. No reaction will occur. HOW PH AFFECTS AN ENZYME • If the pH is to high or low the enzyme will not work, because its shape will change. PH • All enzymes have an optimum pH that they function best at. • If the pH is too low or too high the enzyme will work slow because the change in pH changes the shape of the enzyme making it harder for the substrate to fit in. ANALYZE THE GRAPH AT WHAT PH DOES CHYMOTRYPSIN FUNCTION BEST? TEMPERATURE • Enzymes function best at an optimum temperature depending on the type of enzyme it is. • As the temperature rises the enzyme and substrate molecules move quicker causing more collisions to occur, there for creating more products. • If you make the temperature to high you will destroy the protein (denature) it. WHAT IS THE OPTIMAL TEMP FOR THIS ENZYME AMOUNT OF SUBSTRATE PRESENT • At low substrate concentrations, collisions between enzymes and substrate molecules are rare and reactions are slow. • As the amount of substrates increase so does the collisions between enzymes and substrates. • This continues until the enzymes are saturated.