Atomic Structure of an Atom

Atoms: Smallest particle of matter

Location Charge Subatomic Particle Nucleus Nucleus Neutral Neutron Outside Nucleus in energy levels Negative (-) Electron Positive (+) Proton Location Charge Subatomic Particle

Protons and Neutrons in the nucleus Electrons outside nucleus in energy levels 1st Level: 2 electrons 2nd Level: 8 electrons 3rd Level: 18 electrons

Elements: Groups of the same atoms Important Elements for Biochemistry: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Phosphorus (P), Sulfur (S) CHONPS

Protons = atomic number Neutrons = Atomic Mass - # of protons Electrons = # of protons

With your table partner…. Determine the number of Protons, Neutrons, and Electrons of Lithium Aluminum Sulfur

Answers! Element Name Number of Protons Number of Neutrons Number of Electrons Lithium 3 4 (7-3) Aluminum 13 14 (27-13) Sulfur 16 16 (32-16)

Exit Slip in warmup notebook Choose three different elements and determine the # of protons, neutrons, and electrons

Chemical Compounds

Compounds are… Chemically bonded atoms of 2 or more elements

+ = Hydrogen Oxygen Water

Physical and Chemical Properties of the compound are very different from the elements Sodium (Na) – silver metal, soft Chlorine (Cl) – poisonous, green gas Sodium Chloride (NaCl) – white solid, dissolves in water

O2 H2 NaCl H2O CO2 H2SO4 NH3 C6H12O6

Chemical Bonds - Hold the atoms in a compound together 2 major types

1. Covalent Bonds Elements SHARE electrons Most common type Want to be more stable Example: Water, H2O

2. Ionic Bond Between a metal and nonmetal One atom gains and one atom loses electrons Example: NaCl

Properties of Water

Why is water important? Most abundant compound in most living things Covers over ¾ of the Earth’s surface Liquid at room temperature Expands as it freezes (ice floats on water)

What would be the effects on the world if ice did not float?

Water is Polar… Water has an uneven distribution of electrons between the oxygen and hydrogen atoms Oxygen side: (-) pole Hydrogen side: (+) pole

Hydrogen Bonds Attraction of polar molecules Weaker than ionic or covalent

Cohesion- attraction between molecules of the same substance Examples: water beading, surface tension

Adhesion- attraction between molecules of different substances Examples: water in glass, movement in plants

Solute – substance dissolved (Kool-Aid) Solvent – what the solute is dissolved in (H20)

Water is the UNIVERSAL SOLVENT!! Water’s polarity dissolves ionic compounds and other polar molecules

Resists Temperature Change: Requires more heat to increase temperature than most liquids

Summary of Properties of Water expands when frozen is polar Cohesion, adhesion, Universal Solvent Resists temperature change

Acids, Bases, and pH

Water can be broken down H2O H+ + OH- water Hydrogen + Hydroxide

pH scale: Measures the concentration of H+ ions in a solution Ranges 0 - 14

Acids: H+ > OH- pH < 7 Lower pH = more acidic Ex: Hydrochloric Acid, Lemon Juice, Vinegar

Neutral: pH = 7 Concentration of H+ = OH- Ex: Pure Water

Bases: H+ < OH- pH > 7 Higher pH = more basic Ex: Soap, Bleach, Oven Cleaner

Buffers: Weak acids or bases that react with strong acids or bases to prevent changes in pH Maintain homeostasis in the body When an acid reacts with a base it neutralizes and makes water and a salt

Tell whether each is an acid, base, or neutral 1. pH = 13 2. pH = 3 3. pH = 8 4. pH = 7

Monomer – single unit (one) Polymer – made of monomers (many) Biomolecules Monomer – single unit (one) Polymer – made of monomers (many)

Carbohydrates Made up of C, H, and O Saccharide means sugar 1:2:1 Glucose = C6H12O6 Saccharide means sugar

Monomer: Monosaccharides (contains one sugar) Simple sugars – glucose, fructose Dissaccharides (contain 2 sugars) -examples: lactose (sugar in milk) and sucrose (table sugar)

Polymer: Polysaccharides (contain many sugars) Glycogen or Starch – cellulose Formed by Polymerization

Carbohydrates Importance: Found in: pasta, bread, fruits, sugars Main source of energy Found in: pasta, bread, fruits, sugars

Lipids Mostly C and H Glycerol and fatty acid chains Saturated fats: all single bonds Unsaturated fats: at least one double bond

Lipids Examples Importance: Fats, oils, waxes, steroids Store energy Part of membranes (cell) Waterproofing

Nucleic Acids Made of H, O, N, C, and P Monomers: Nucleotides – sugar, phosphate, and base

Nucleic Acids Examples: Importance: DNA, RNA Store and transmit genetic information

Proteins Contain N, C, H, and O Monomers: Amino Acids 20 types Identical except for R groups Joined by covalent (Peptide) bonds

Proteins Foods found: Importance: Meat, nuts, beans, eggs Control reactions Regulate cell processes Form muscle Fight disease

Enzymes are… Proteins that act as biological catalysts Catalyst: substance that speeds up the rate of a chemical reaction

Enzymes work by lowering the activation energy