Nucleus – Protons and Neutrons

Subatomic Particles Protons – mass ~ 1amu, charge = +1 Neutrons – mass ~ 1amu, no charge Electrons – mass ~ 0, charge = -1

Atomic Number – Number of protons in the nucleus of an atom Mass Number – Total number of particles (Protons and Neutrons) in an atom

Isotopes –same element (# of. protons) with different mass Isotopes –same element (# of protons) with different mass numbers (# of neutrons) Radioactive isotopes – isotopes that spontaneously decay Half-Life – the time for ½ of the isotopes to decay

IVA Atomic Number Atomic Mass

Electron Energy Levels 1st Energy level holds 2 electrons 2nd and Higher hold 8 electrons (Octet Rule)

http://sci2k.net/periodictable.html 1 2 2 2 2 2 2 2 2 2 2 2 3 4 5 6 7 8

Nucleus H-1

Nucleus He-4

Nucleus Li-5

Li-5 ion Nucleus Li+

Nucleus Be-9

Nucleus Be-9 ion Be 2+

Nucleus Be-9

Nucleus B-11

Nucleus C-12

Nucleus C-14

Nucleus N-14

Nucleus O-16

Nucleus F-19

Nucleus F-19 ion F-

Nucleus Ne-20

Nucleus Na-23

Nucleus Mg-24

Nucleus Al-27

Nucleus Si-28

Quiz An atom of Oxygen-17 would have ___ protons. An atom of Sulfur-33 would have ___ electrons. An atom of Helium-5 would have ___ neutrons.

Quiz 4. An atom is discovered with 12 electrons, 12 protons and 13 neutrons. What is it?

Quiz An atom of Oxygen-17 would have ___ protons. 8 protons 2. An atom of Sulfur-33 would have ___ electrons. 16 electrons 3. An atom of Helium-5 would have ___ neutrons. 3 neutrons

Quiz 4. An atom is discovered with 12 electrons, 12 protons and 13 neutrons. What is it? Magnesium-25

Metals Metals Properties of Metals Shiny – luster Conductors (electricity and heat) Malleable Solids (except Hg) Metals – tend to lose electrons when forming ions Usually 3 or less e-s in outer level

Nonmetals Nonmetals Properties of Nonmetals Dull Good insulators (heat and electricity) Brittle solids or gases Nonmetals tend to gain electrons when forming ions Usually 5 or more electrons in outer level

Metalloids (Semiconductors) Metalloids have some properties of both metals and nonmetals

Pursuit of Full or Empty Energy Levels Atoms are more stable when their outer E level is full or empty To achieve this they will Steal, Give up, or Share electrons

Ions – atoms that have gained. or lost electrons when Ions – atoms that have gained or lost electrons when forming ionic bonds Ca+ions – positive ions, have lost an electron (metals) Cations Anions – negative ions, have gained electrons (nonmetals) Anions

Ionic Bond – attraction between oppositely charged ions Covalent Bond – atoms share electrons to fill outer E level

Chemistry of Water Cohesion sticks to other water molecules

Chemistry of Water Adhesion sticks to other polar molecules

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Chemistry of Water Specific Heat holds large amounts of heat, stabilizes temperature Universal Solvent dissolves most ionic compounds (salts)

Chemistry of Water Special Thermal Expansion Water increases in volume when it freezes Making ice less dense than liquid water

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Solution – a uniform mixture Water is the “Universal Solvent” Solution – a uniform mixture Solvent - dissolves the other substance Solute – substance that is dissolved

Hydrophilic- water loving Ionic or polar substances (Salts) Hydrophobic- water fearing nonpolar substances (oils)

Acids - pH less than 7 more H+ than OH- ions Bases - pH greater than 7 more OH- than H+ ions Neutral – pH of 7 equal H+ and OH- ions Buffer – controls pH by donating or accepting H+

pH – is based on powers of 10 pH # is actually 10-# pH 7 is actually 10-7 = 0.0000001 pH 1 is actually 10-1 = 0.1 pH 12 is actually 10-12 = 0.000000000001

Chemical Reactions Chemical Reactions

Chemical Reactions Change Substances Yeast + sugar => carbon dioxide and ethanol Chemical Reactions – occur when substances undergo chemical changes to form new substances Atoms are rearranged to form new compounds or molecules

Reactants and Products H2 + O2 => H2O Reactants – the substances that enter a reaction (left) Products – substances that are produced by the reaction (right)

Chemical Energy Chemical Energy – energy stored in chemical bonds, can be released in a reaction Exothermic – (Exo = out)(therm = heat) Reactions that release energy as light, heat or sound Endothermic – (Endo – enter) Reactions that absorb energy form the environment

Activation Energy All reactions need some energy to begin

Catalysts Catalysts are substances that increase the rate of a reaction, but are not used in the reaction They lower the activation energy

Enzymes Enzymes are protein catalysts in your cells Substrate is the molecule targeted by the enzyme

Enzymes Enzymes are protein catalysts in your cells Substrate is the molecule targeted by the enzyme

Enzymes are Specific Each enzyme works on one reaction

Deactivated enzyme pH Temperature