Presentation on theme: "Unit 2 Ecological Biochemistry"— Presentation transcript:
1 Unit 2 Ecological Biochemistry Unit 2A: Basic Chemistry
2 Atoms are the Basic Units of Matter Atoms are incredibly small. Placed side by side, 100 million atoms would make a row only about 1 centimeter long—about the width of your little finger!
3 What are Atoms made of?Atoms are made of particles called protons, neutrons, and electrons.Protons have a positive (+) chargeElectrons have a negative (-) chargeNeutrons are neutral (no charge)Atoms normally have equal numbers of electrons and protons, making them neutral
4 Elements Elements are pure substances made of only one type of atom Elements are listed in the periodic table of elementsThey are arranged in order of their atomic numbersAn atom is the smallest unit of an element that has the properties of that element
5 Atomic Number and Mass Number The atomic number of an element is the number of protons (typically the same as the number of electrons)The mass number of an element is the number of protons plus the number of neutrons
7 ElementSymbolAtomic NumberMass NumberNumber of ProtonsNumbers of NeutronsNumber of ElectronsHeliumHe24MagnesiumMg12ZincZn306535BromineBr8045AluminumAl1314
8 Important Elements for Biology The five most abundant elements in living things are:Hydrogen – 10%Oxygen – 65%Nitrogen – 4%Carbon – 19%Phosphorus – 1%HH
9 Molecules, Compounds, and Chemical Formulas A molecule is made when 2 or more of any atom are joined together (Ex: O2, H2O)A compound is a substance formed by the combination of two or more different elements (Ex: H2O, C6H12O6)All compounds are molecules, but not all molecules are compoundsChemical Formula- written shorthand showing the composition of a compound
10 Chemical FormulasCoefficient: tells how many molecules of that substance (the large number BEFORE the formula)Subscript: goes with the element symbol preceding the number; tells how many atoms of that element within one molecule of the substance (small number WITHIN the formula).
12 Example 2: 6CO2 What is the coefficient? _______ What is carbon’s subscript? ________What is oxygen’s subscript? ________How many molecules of this compound are represented by this formula? _________How many atoms TOTAL are present in this molecule?______
13 Chemical BondsThe atoms in compounds are held together by chemical bonds.Making bonds involves the electrons that surround each nucleus.The electrons that are available to form bonds are called valence electrons.
14 This type of drawing is called a Bohr model Valence ElectronsThe electrons of an atom are spread out in different layers around the nucleus to make an “electron cloud”These layers are called energy levels2 electrons go in the first energy level8 electrons can go in the second energy level and beyond (octet rule)This type of drawing is called a Bohr model
15 Valence Electrons (cont.) If there are not 8 electrons for the outer level, these empty spots are called vacancies and some electrons are thus unpairedThe unpaired electrons in the outer layer are the valence electronsThe valence electrons can pair with those from other atoms to “fill” the vacancyThis creates a molecule
16 Bohr Model vs. Lewis Dot Structure Lewis Dot Structure: shows just the valence electrons in the outer energy levelBohr Model: shows all of the electrons in their energy levels
17 Reactive vs. StableThe reactivity of an atom is determined by the number of vacancies in its outer energy levelIf there are vacancies, the atom is reactive/unstableIf there are no vacancies, the atom is nonreactive/stableIf the vacancies are filled due to bonding, the molecule is stable
18 The main types of chemical bonds are 1. ionic bonds2. covalent bondsThere are other types of bonds and interactions but they are not as strong as these two types
19 1. Ionic BondsAn ionic bond is formed when one or more electrons are transferred from one atom to another.An atom that loses electrons becomes positively charged.An atom that gains electrons has a negative charge.These positively and negatively charged atoms are known as ions.These oppositely charged ions have a strong attraction for each other, forming an ionic bond.
20 2. Covalent BondsWhen electrons are shared by atoms instead of transferred.The moving electrons travel about the nuclei of both atoms, forming a covalent bond.
21 A covalent bond can be a… Single Covalent Bond: atoms share 2 electrons (1 pair)Double Covalent Bond: atoms share 4 electrons (2 pairs)Triple Covalent Bond: atoms share 6 electrons (3 pairs)
22 HONCThis is the number of bonds each of these can form!H O N CBonds between the most important biological atoms will be covalentThe number of bonds each can make is important for the compounds that will be created using these atomsHydrogen -can form 1 single bondOxygen- can form 2 single bonds or one double bondNitrogen- can form 3 single bonds or 1 double bond and 1 single bondCarbon- can form 4 single bonds or 2 double bonds, or 1 double bond and 2 single bonds (no quadruple bond!)
23 Structural formulas Show you the types of elements in the molecule the number of atoms of each element ANDthe arrangement of atoms and location of covalent bonds. Shows the two dimensional shape of the molecule.
24 Chemical ReactionsChemical Reactions: process that changes or transforms one set of chemicals into another set of chemicals. Involves changes to the chemical bonds that join atoms in compounds.Reactants: elements or compounds that enter into a chemical reactionProducts: elements or compounds produced by a chemical reactionHINT: Reactants react to produce products!Bonds of the reactants are broken and new bonds form in the products
25 Chemical EquationsWhat process is this equation for?Chemical Equation: a mathematical representation of a chemical reaction. It shows the numbers and types of compounds involved.6O C6H12O CO H2O ___
26 Balancing Chemical Equations The Law of Conservation of Matter: matter (atoms and elements) in a chemical reaction cannot be created or destroyed. Only the arrangement of the atoms is changed, NOT the number or types.Therefore both sides of a chemical equation must be “balanced” (have the same number of atoms).
27 Are these equations balanced? C + 2H2 --> CH4Na2SO4 + CaCl2 --> CaSO4 + NaClC2H6 + O2 --> CO2 + H2O2Al2O3 --> 4Al + 3O2