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Chapter 2 The Chemistry of Life Section 2-1: The Nature of Matter Atom – Greek “atomos” – indivisible. Named by Democritus Subatomic Particle Charge The basic unit of Protons Positive 1 all matter Made up of Neutrons Neutral subatomic particles: Electrons Negative 1 Mass Where found 1AMU “Nucleus” 1 AMU “Nucleus” 1/1840 Orbitals Periodic Table of Elements Table that lists all the names & important information of elements • Element – A pure substance consisting of only 1 kind of atom – Know the elements given to you and their symbol Atomic Number = the # of 6 C Atomic Mass 12 Atomic number Protons (= the # of electrons) Atomic Mass = the # of Protons + the # of Neutrons *All atoms are electrically neutral so the # of Protons must = the # of Electrons Figure out the following elements 8 O 16 # Protons # Electrons # Neutrons 1 H 1 7 N 14 11 Na 23 17 Cl 35 Bohr Model of the Atom Has electrons orbiting the nucleus in a set pattern – – Protons and Neutrons are in the nucleus Electrons orbit the nucleus in orbitals or energy levels • • 1st orbital gets a max of 2 electrons 2nd and 3rd orbitals gets 8 electrons Nitrogen Make Bohr models for the 6 elements below C H O N Na Cl 12 Mg 24 19 K 39 16 S 32 14 Si 28 Isotopes Elements with the same atomic number but different atomic masses (# of neutrons). 6 6 8 8 C C O O 12 14 16 18 Radioactive Isotopes Are used to follow chemical pathways as markers or for medicinal purposes in the treatment of cancer. Also used as radioactive tracers How do elements come together? Compounds “Compere” to come together - a substance made up of 2 or more elements in definite proportions Ie. H2O, CH4, C6H12O6, NaCl *The compound will have different chemical and physical properties from the elements that it is composed of ie. NaCl + Element 1 Carbon 2 Magnesium 4 Sodium 5 6 12 Number of Protons Number of Electrons # Electrons in ourter most orbital 11 23 17 35 12 N Chlorine H 8 S Iodine 1 16 53 127 53 10 Si 14 11 Ca 20 12 P 13 Iron 14 Aluminum 15 15 31 26 30 Copper 17 Zinc 18 Arsenic 19 25 29 XX 64 XX 35 30 As K Fluorine XX 13 Mn 16 20 Number of Neutrons 8 12 7 9 Atomic Mass O 3 6 Symbol Atomic Number 19 19 9 XX Chemical Bonding Na11 Cl17 1. Ionic bonds – transfer electrons between elements • Since Na has 1 “spare” electron in its outer energy level and Cl needs 1 more electron to fill its outer energy level, Na will transfer 1 electron to Cl’s outer energy level. This is Ionic bonding What results is Na+Cl-. – Na lost 1 electron so it has 1 extra positive charge – forms a + ion. – Cl gained an electron so it has 1 extra negative charge – forms a – ion • Ions – are charged particles that result from ionic bonding Na+Cl- Try Magnesium and Sulfur Mg12 S16 Covalent Bonding H1 O8 Results when atoms share a pair of electrons. The outer energy level will therefore be filled for both atoms involved These are the strongest of bonds needing high energy to break them or enzymes (to be discussed later) In the case of water, both H’s shared electrons with the oxygen Do CH4 (Methane) & HCl (Hydrogen Chloride) CH4 Chemical NH3Formulas H 2O Bohr Models Structural/Molecular Diagrams Methane Ammonia Water Lewis Electron Dot Configuration C6 N7 Ne10 F9 H1 B5 Using the model kits, make the following: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. H2O O2 CH4 HCl O3 CO2 H2 SiO2 C2H6 C2H4 C2H2 C3H8 NH3 O– Blue – 2 C – Black – 4 N– Red – 3 H – White – 1 Cl – White – 1 Si – Black – 4 Ethane Ethylene Acetylene Propane Ammonia Tubes – Covalent Bonds Draw Structural Diagrams of Each Molecule Smallest unit of a compound. • H2O (1 molecule of water) • 2H2O (2 molecules) • C6H12O6 (1 molecule of glucose) • 3C6H12O6 (3 molecules of glucose) Section 2-2: Water! 65% of you is made up of water! Hydrogen + Hydrogen Oxygen Water is a polar molecule – the Oxygen side of it has a more negative pull than … - the Positive pull of Hydrogen Because of this polarity, when something (like Na+Cl -) that is bonded ionically is placed in solution with water, it Dissociates (the ions separate). • The positive ions will be attracted to the negative side of water (the oxygen side) and the negative ion will be attracted to the positive side of water (the hydrogen side). • This makes water the Universal solvent. • Therefore, ionic bonds are weak bonds Dissociation of Salt in Water Hydrogen Bonding • Since water is polar, the Hydrogen side (+) of the molecule will be attracted to the negative side of water (oxygen side). • This special type of attraction is called Hbonding • and is a very weak bond. Other attractive forces 1. Cohesion – like molecules being attracted to each other. As with water droplets 2. Adhesion – unlike molecules being attracted to each other. As in water being attracted to the glass of a graduated cylinder forming the meniscus 3. Capillarity – a combination of the two results in a liquid being moved through a very thin tube. Upward force. Greater in smaller tubes than in larger tubes. Like using a small straw to pull up a liquid versus a fat straw. Mixtures and Solutions • Mixtures – composed of 2 or more compounds or elements that are physically mixed together. Your blood cells in plasma. Salt and pepper together in a shaker Iron fillings and salt • Solutions Solution demonstration – A mixture made by ionically bonded compounds dissociating in water – Solute – compound that is dissolved in a solution with water. • Na+ Cl- – Solvent- The substance in which the solute is dissolved in. • Water • Water may react to form ions (even though it is bonded covalently) due to its polarity. H2O • • H+ + OH- H+ = Hydrogen ion OH- = Hydroxide ion • If the number of H+ ions in a solution is = to the # of OH- ions, the solution is neutral If the H+ ions are > the OH- ions, then the solution is an acid If the OH- ions are > the H+ ions, then the solution is a base or alkaline. The pH scale • is a measurement of the concentration of H+ ions to OH- ions. – Each step on the scale represents a 10 fold change. Acidic 0 1 2 Do pH lab 3 Neutral 4 5 6 7 8 Alkaline 9 10 11 12 13 14 pH • Scale from 0 – 14 to show how acidic or alkaline a solution is • Logarithmic scale – (10 fold >/< for each step) Activity 1. Using universal pH paper, determine the pH of the following solutions 2. Dip the tip of the pH paper into the solution, wait a minute and compare it to the colored scale on the vial 3. List the pH’s of the following solutions: a. b. c. d. e. f. g. h. i. j. ammonia vinegar milk black coffee baking soda solution cola Milk of Magnesia lemon juice Water Draino 4. On a blank pH scale, place the solutions in the proper spot pH lab data table Solution pH Amount of H+ or OH from Neutral a. Ammonia (get results immediately) b. Vinegar c. Milk d. Black Coffee e. Baking Soda (stir well) f. Cola g. Milk of Magnesia (stir well) h. Lemon Juice i. Water j. Soap k. Draino (get results immediately) Ie. For a pH of 8, it has 10 x OH- Buffers – pH of most cells’ fluid is 6.5 – 7. Needs to maintain homeostasis To do this, buffers are weak acids (carbonic acid in blood) or bases that will act to prevent sharp changes in pH. Neutralization – occurs when opposites on the pH scale are added together to create water and a salt. Antacids H+Cl- + Na+OHNa+Cl- + H2O Reactants Products Neutralization lab Atoms without Eves Mendeleev's Chart Atoms together Let's Bond Water, water everywhere What's the Solution Democritus called them atoms because… These are pure substances made up of only 1 kind of atom These are made up of elements in a definite proportion Where all this bonding takes place Unique property of water when it freezes Subparticles of an atom C, H, O, N, Na, Cl, P, K, S; stand for? 2H2O2 contains how many molecules? Two main types of chemical bonding C6H12O6 has how many atoms of each element? Charge of each of the above 35Cl 17 Its atomic # & mass in that order pH This How strong are you? This is made of 2 or > compounds physically together Water's real name If the concentration of H+ and OH- ions is equal Unique property of water that allows it to be the Unversal solvent Type of the above that salt water would be Two types of ions formed by water pH of most cells in human body Bonding that transfers electrons Force that draws water up a straw or plant roots What the salt in salt water would be If an acid, it has more of this type of ions % of water in humans Mass of each of the above How many protons and electrons does the above have? Ratio of H:O in water Bonding that shares electrons Which side of a water molecules has a positive pull What the water in salt water would be If a base, these ions are found in greater concentration Weak acids or bases that prevent sharp changes in pH Where to find the 2 subatomic particles with mass # of Neutrons in the above Type of change that occurs when forming a compound Type of bonding that forms salt Type of "bond" formed between H & O of another water molecule What water does to ionically bonded compounds in solution w/ it Scale which measures the concentration of the ions When opposite but equal strength on the pH scale are combined Where the smallest particles are found What if the # was 36 instead of 35? What's it called and why? What happens to the individual properties of the atoms when a compound is formed What Na+ and Clare after bonding A molecule being attracted to its own kind A mixture of water and a nondissolved material Stongest pH for an acid What is formed when the above happens Charge on any atom # of electrons in each of the above's orbits What information a chemical formula gives Molecules being attracted to different kinds of molecules What would salt and pepper together be considered? Strongest pH for a base If Vinegar has a pH of 2, how many more H+ does it have more than water? How water & methane bond Atoms without Eves Mendeleev's Chart Atoms together Let's Bond Water, water everywhere What's the Solution pH This How strong are you? unable to be cut Elements Compounds Between the electrons It expands Mixture Hydrogen Hydroxide Neutral or 7 Protons, Neutrons and electrons Carbon, Hydrogen, Oxygen, Nitrogen, Sodium, Chlorine, Phosphorus, Potassium & Sulfur 2 Covalent and Ionic It is Polar Solution Hydrogen(H+) & Hydroxide (OH-) 6 to 7 Positive 1, neutral and Negative 1 Atomic # = 17, Atomic Mass = 35 6 - Carbon, 12 - Hydrogen 6 Oxygen Ionic Capillarity (capillary action) Solute H+ 65% Protons & Neutrons are 1, electrons are 1/1840 or zero 17 2 to 1 Covalent Hydrogens' side Solvent OH- Buffers Protons and Neutrons are in the nucleus 18 Chemical change Ionic Hydrogen bond Dissociates them pH scale Neutralization Electrons orbit in an electron cloud Isotope New properties will be formed different from original Ions Cohesion Suspension 0 Water and a salt Neutral 2, 8, 7 Type and # of each atom present Covalently (H2O & CH4) Adhesion Mixture 14 1 x 106