Download 1 Chapter 2 Section 1- Nature of matter Atom: smallest unit of

Chapter 2
Section 1- Nature of matter
Atom: smallest unit of matter that cannot be broken down and still be the same element Element: a substance made up of only one kind of atom. (examples: oxygen, gold) Atom is made of three particles: Particle charge found where in the atom 1. Proton positive + nucleus (the center of the atom) 2. Neutron no charge (neutral) nucleus 3. Electron negative -­‐ outside of nucleus For every proton there is one electron, making atoms neutral (no electrical charge). Usually, there are also the same number of protons and neutrons. Electron arrangement (simplified): In circles (shells) around nucleus; first shell holds maximum of 2 electrons, all others holds a maximum of 8 electrons, The outer-­‐most shell is called the valence shell. Some scientists use the term electron cloud. Size of the nucleus compared to whole atom: A pea in the middle of a football field would be the nucleus, electrons would be at the edge of field (Leave room for drawing of an atom) Periodic Table: -­‐ Atoms are represented by one, two or three letters, for example H = hydrogen, Au = gold -­‐ Elements differ from other elements by the number of protons (or electrons) -­‐ -­‐ -­‐ -­‐ Atomic number (above the letter of the element) = equal to the number of protons -­‐ Atomic weight (below the letter of the element) = equals the number of protons and neutrons. -­‐The nucleus is very dense and the heaviest part of the atom. Electrons weigh barely anything. -­‐ Group (or column) numbers tell how many electrons are in the valence shell. (hand out periodic table and fill in column numbers) 1 All atoms “want” to be stable, like the noble gases in column 8. They try to fill up their valence shell (with up to 2 or 8 electrons). Elements in columns 4-­‐7 will gain electrons to have 8; elements in columns 1-­‐3 will lose electrons. Ion: an atom or molecule that has lost or gained one or more electron(s) Drawing: Chemical formula: shows the arrangement of the elements when two or more bond together. Example: C6H12O6 (sugar) Subscript: O2 -­‐ Number that follows the letter -­‐ tells how many atoms there are of an element (in this case there are 2 oxygen atoms) Coefficient: number in front of a compound or element; tells how many molecules there are 3 H2O = 3 water molecules = 3x2 atoms of hydrogen = 9 atoms total + 3x1 atoms of oxygen Molecule: two or more atoms join together chemically; can be of the same element or not. Examples: O2, H2O, NaCl, CO2 Compound: two or more elements joined together, for example H2O (water) Must be different elements. H2O = 2 atoms of hydrogen plus one atom of oxygen. Al compounds are molecules but not all molecules are compounds. Physical qualities of compounds are different from those of its elements. Examples: H20, NaCl, CO2 What is the difference between molecules and compounds? Compounds must consist of more than one element Isotopes: some elements exist in more than one version: they have different numbers of neutrons. Examples: carbon-­‐12 carbon-­‐13 carbon 14 (for drawings see Dragonfly book p. 36) 2 Chapter 2 Section 2- Water and Solutions
Acids and Bases • Chemical formula for water: H2O • Acids form hydrogen ions (H+) in water. • Bases reduce hydrogen ions and form hydroxide ions (OH-­‐) in water -­‐ Solutions are more acidic, the more H+ they have -­‐ Solutions are more basic, the fewer H+ they have • Indicators: things that detect acids and/or bases: Litmus paper: turns blue with bases, red with acids pH paper: different colors depending on scale Drawing of pH scale: 3 Chapter 2
Section 3 - Chemistry of Cells
ORGANIC COMPOUNDS: contain carbon Also called organic molecules or macromolecules which means ________________ Definitions: Macro means ________________. Micro means ____________. Poly means ________________. Mono means _____________. Polymer: a substance that consists of smaller pieces; example: __________ Monomer: one part of the polymer; example: ___________ The four large organic compounds (the polymers)are: 1. Carbohydrates 2. Lipids 3. Proteins 4. Nucleic acids The one small (monomer) organic compound in the body is: ATP(a single molecule) Which macromolecules are found in food? ________ Which macromolecule is not found in food? _______________ 1. Carbohydrates: Compounds composed of ________________, _________________, and _______________ (CHO) For example glucose: C6H12O6 – 6:12:6 = 1:2:1 Another term for carbohydrates is saccharides or sugars. There are a. monosaccharides (mono = one) Examples: glucose, fructose b. disaccharides (di = two) Example: glucose + fructose = sucrose c. polysaccharides (poly = many = three or more) Example: starch Function: Carbohydrates give us __________. The cellulose (polysaccharide) in vegetables and fruit provides fiber. Food examples: grains (pasta, bread), fruit, vegetables, beans Drawings: 4 2. Proteins: Compounds composed of carbon, _____________, oxygen, ____________ and sometimes sulfur (CHONS). Function: Proteins repair our bodies. Examples of protein in foods: meat, fish, eggs, beans (plant foods have less protein than foods that come from animals) Proteins are made of smaller pieces (monomers) called ___________________. There are 22 different amino acids. Each protein molecule is made of hundreds of amino acids (animal protein contains all 22, plant protein not all 22) Structures made of protein: muscles, enzymes, hormones (control and regulate many body functions), hemoglobin (transport oxygen in the blood), antibodies (protect from disease), hair, and feathers. (leave room for drawing) 3. Lipids: Compounds composed of ___________, hydrogen, _____________, and some have phosphorus. Include fats, oils, waxes and steroids. Do not dissolve in water. Functions: energy storage and insulation. Kinds of fats: 1. Saturated fats (animal fats): single bonds between atoms, harder to break. Examples: butter, lard, fat on meat. 2. Unsaturated fats (plant fats): have double or triple bonds; easier to break. Examples: olive, corn, canola oils. A typical fat (polymer) consists of 3 strands of fatty acids with a glycerol backbone (the two monomers). Waxes, steroid, and other lipids look slightly different. Monomer: 5 Polymer (Saturated fat): Polymer (unsatured fat): 6 4. Nucleic Acids: molecules composed of carbon, _____________, oxygen, nitrogen and phosphorus. Nucleic acids are made of units called nucleotides. Nucleotides have three parts: 1. Five-­‐carbon sugar 2. Nitrogen-­‐containing base 3. Phosphate group There are two kinds of nucleic acids: a. DNA (deoxyribonucleic acid) – two strands b. RNA (ribonucleic acid) -­‐ one strand (leave room for drawing) 5. ATP: Single nucleotide with two extra energy-­‐storing phosphate groups. Used for temporary storage of energy. (leave room for drawing) 7 Chapter 2
Section 4 - Energy and Chemical Reactions
Energy is the ability to move or change matter. • Exists in many forms (light, heat, chemical, etc.) and can be converted from one form to another. • Energy can be stored or released by chemical reactions (chemical bonds are formed or broken) Chemical reactions: • Starting material: reactants • Newly formed substances: products o Reactants ⇒ Products o NaCl ⇒ Na + Cl • Metabolism: all the chemical reactions that occur within an organism (energy comes from food) Activation energy: Is a chemical “push” (like pushing a boulder down a hill) to get a reaction started. Enzymes reduce the activation energy needed and speed up chemical reactions. Without enzymes reactions would be too slow to sustain life (one thing you would die of is carbon dioxide poisoning). Enzymes (made of protein): 1. are specific to one single reaction 2. can be re-­‐used 3. have active sites that fit a particular molecule. 4. substances that enzymes act on are substrates (same as reactant) (copy drawing p.41) 5. Enzymes need: a certain temperature, a certain pH Complete data lab p. 42 8