Ch 2
Upcoming SlideShare
Loading in...5
×
 

Ch 2

on

  • 688 views

Chapter 2 notes

Chapter 2 notes

Statistics

Views

Total Views
688
Views on SlideShare
688
Embed Views
0

Actions

Likes
0
Downloads
7
Comments
0

0 Embeds 0

No embeds

Accessibility

Categories

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

Ch 2 Ch 2 Presentation Transcript

  • CHAPTER 2 WARM UP & LEARN THE LINGO
  • ADDITIONAL RESOURCES
    • Atom
    • Isaac Asimov
    • ISBN:0613033884
    • Any chemistry by Asimov is good
  • WARNING
    • The material from this point on may start out sounding like high school chemistry
    • The high school sounding material is like a runway, we use it to take off from
    • Don’t get board or over-confident with the runway, or you WILL miss the flight
  • ATOMIC THEORY
    • Has been around for over 2,000 years, the word ATOM is from the Greek word atomos meaning uncuttable
    • In the early 1800s, atomic theory was dusted off and formed the basis of modern chemistry
    • From here forward, we are talking about the 1800s flavor of atomic theory
  • ATOMIC THEORY
    • Four “postulates” (rules):
    • Each element is composed of very small particles called atoms
    • Atoms of a given element are identical to each other in mass and properties, but are different from atoms of other elements
    • Atoms of one element can not be changed into atoms of a different element
    • Compounds are formed when atoms of two or more elements combine
  • ATOMIC THEORY
    • Explained two laws:
      • Constant Composition – Compounds always have the same ratio of elements
      • Conservation of Matter – The total mass of material after a chemical reaction is the same as the total mass before the reaction (this is the basis for everything that will follow in this class)
  • ATOMIC THEORY
    • A new law was discovered at this time, the Law of Multiple Proportions:
    • If two elements A and B combine to form more the one compounds, the ratio A to B will be different for each compound.
    • NO 2 , NO 3 (NOx, they cause smog)
    • SO 2 , SO 3 (SOx, they cause acid rain)
  • ATOMIC STRUCTURE
    • Please forget the “Pool Ball” “Planets Around the Sun” image of electrons
    • Electrons act very strangely
    • For accounting purposes, if we need to, electrons will be drawn as dots or minus signs next to the atomic symbol
  • ATOMIC STRUCTURE
    • Read the text book if you want a pitch – by – pitch description of who did what when (this is chemistry, not history)
    • Atoms have two regions – the nucleus and the electron cloud
    • If this dot ● were a nucleus, the electron cloud would be on the third floor
  • ATOMIC STRUCTURE THE NUCLEUS
    • Two particles in the nucleus:
      • Protons
      • Neutrons
  • ATOMIC STRUCTURE THE NUCLEUS
    • Protons
    • Have an atomic mass of just under 1
    • Have a charge of +1
    • Do not participate in chemical reactions
    • Determine what element the atom is
  • ATOMIC STRUCTURE THE NUCLEUS
    • Protons
    • 1 proton is Hydrogen
    • 8 protons Oxygen
    • 92 protons is Uranium
    • Protons
    • We call the NUMBER of protons in an atom the ATOMIC NUMBER since it determines what element it is
    ATOMIC STRUCTURE THE NUCLEUS
    • Neutrons
    • Have an atomic mass of 1
    • Have a charge of 0
    • Do not participate in chemical reactions
    • Atoms of the same element can have DIFFERENT numbers of neutrons
    ATOMIC STRUCTURE THE NUCLEUS
    • Neutrons
    • Atoms of the same element with different numbers of neutrons are call isotopes
    • Isotopes of an element have different weights, but they have identical chemical properties (which is why it’s so hard to separate them)
    ATOMIC STRUCTURE THE NUCLEUS
    • If an atom of carbon (atomic number 6) has 12 neutrons what is it’s atomic weight?
    • 6 protons (weight ≈1)
    • 12 neutrons (weight = 1)
    • 18 AMUs (Atomic Mass Units)
    • Carbon has an isotope with 14 neutrons it’s weight is 20 AMUs
    • 1 AMU = 1.66054 * 10 -24 grams
    ATOMIC STRUCTURE THE NUCLEUS
    • On the periodic table, carbon weight is listed as 12.0107, the extra 0.0107 is from the carbon 14. What fraction of carbon is C14?
    • X*12+y*14 = 12.0107 x+y=1
    • (1-y)12+14y=12.0107 x=1-y
    • 12-12y+14y=12.0107
    • 2y=0.0107, y=0.0054 or 54 of 10,000
    ATOMIC STRUCTURE THE NUCLEUS
    • Nomenclature
    • To write atomic isotopes
      • Write the atomic symbol C
      • Write the mass number as a superscript to the LEFT of the symbol 12 C or 14 C
      • There is no need to write the atomic number since it is constant for the element (carbon is 6)
    ATOMIC STRUCTURE THE NUCLEUS
    • Don’t think of electrons as moons orbiting a planet
    • Think of them as making concentric shells around the nucleus
    ATOMIC STRUCTURE THE ELECTRON CLOUD
    • Electrons are most probably in the shell
    • Each shell level has a certain number of electrons it can hold (remember this in a few slides when we get to the periodic table)
    • How electrons behave in these shells determine the elements chemical and sometimes physical properties
    ATOMIC STRUCTURE THE ELECTRON CLOUD
  • THE PERIODIC TABLE
    • Some elements have very similar chemical properties
    • When Nobel listed the elements in increasing order of atomic number, he noticed that the every so often, he came to a non-reactive gas that was followed by a soft, reactive metal
    • He also noticed that the elements in between also repeated in a pattern
    • So he arranged the elements with similar properties in groups.
    • He listed the groups as columns going from light on top to heavy on the bottom
    • The groups were arranged next to each other left to right by increasing atomic number of the first element
    THE PERIODIC TABLE
  • THE PERIODIC TABLE
  • THE PERIODIC TABLE
    • Columns are called Groups and have similar properties
    • Rows are called Families and are filling the same “levels” of electron shells
  • THE PERIODIC TABLE
    • Some Groups
    • Alkali Rare Halogens Nobel
    • Earth Gasses Metals
    • How to read the table
    • Atomic Number
    • Atomic Symbol
    • Atomic Weight
    • Some fancy tables will also have the electron configuration on the bottom.
    THE PERIODIC TABLE 47 Ag 107.8682
  • MOLECULES
    • Diatomic Molecules
    • Are made of two atoms of the same element O 2 , H 2
    • Remember the name BrINClOHF
      • Br – Bromine ●I - Iodine
      • N – Nitrogen ●Cl – Chlorine
      • O – Oxygen ●H – Hydrogen
      • F - Fluorine
    • Formulas - Three Main Types
    • Molecular – Types and actual number of atoms involved (H 2 O, CS 2 , MgCl 2 H 2 O 2 )
    • Empirical – Types and ratio of atoms involved ( HO )
    • Structural – Types, amounts, & how they are put together
    MOLECULES
    • Ions & Ionic Compounds
    • All atoms want to have a full outer shell of electrons (either 2, 8, 10 or 14)
    MOLECULES
    • Ions & Ionic Compounds
    • On the periodic table, elements on the left (metals) loose electrons and become positively charged. They are called CATIONS (Plus cats)
    • Elements on the right gain electrons and become negatively charged. They are called ANIONS (minus onions)
    MOLECULES
    • Ions & Ionic Compounds
    • “Opposites attract” Paula Abdul 1986
    • Ionic reactions happen when a metal looses electrons with a non-metal.
    • The metal becomes positive, the non-metal negative and form the ionic compound
    • Ionic compounds are usually soluble in water
    MOLECULES
    • Ions & Ionic Compounds
    • Magnesium Chloride
    MOLECULES Mg - Cl - - - - - - - - Cl - - - - - - -
    • Ions & Ionic Compounds
    • Magnesium Chloride
    MOLECULES Mg +2 - Cl -1 - - - - - - - - Cl -1 - - - - - - -
    • Ions & Ionic Compounds - Magnesium Chloride
    • We now have Mg +2 and 2Cl -1
    • We started with zero net charge, and we ended with zero net charge + 2+2( - 1) = 0
    • The formula is MgCl 2
    MOLECULES
    • Cross Method of Empirical Formulas
    • Mg +2 Cl -1
    MOLECULES 2 1 Full shells are happy shells!!!! Why don’t noble gasses participate in reactions?
    • Anticipating Ionic Charge
    • Mg formed a +2 ion and is in the second family from the left
    • Cl formed a -1 ion and is in the second family on the right
    • The family all the way on the right are the noble gasses. They are stuck up and don’t count!
    MOLECULES
    • Anticipating Ionic Charge
    • Cations – If not in the center “short rows”, count from the left. That’s the charge the element will usually form
    • Anions – Skip the noble gas column and count to the left
    • At 4, charges switch
    MOLECULES
    • Anticipating Ionic Charge
    • Elements in the middle (transition metals) form cations, but can vary in charge from 1 to 7
    MOLECULES
    • Elements on the immediate right of the transition metals are called metalloids and usually do not form ions.
    MOLECULES
    • Covalent Bonds
    • Ionic bonds transfer electrons from one atom to another setting up an electrical attraction
    • Covalent bonds occur when two atoms share electrons
    • At any given instant the electron could be with atom 1 or atom 2
    • Covalent – Cumby a
    MOLECULES
    • Covalent Bonds
    • Organic molecules use covalent bonds
    • Carbon and silicone can both bond with itself
    • Chains of carbon atoms make organic molecules
    • The magic number is 4 each carbon forms 4 covalent bonds
    MOLECULES
    • Covalent Bonds – Alkanes – Single C – to- C Bonds
    MOLECULES methane ethane propane
    • Covalent Bonds – Alkenes – Double C – to- C Bonds
    MOLECULES ethene propene
    • Organic Molecules & the Covalent Bond
    • One final note – unlike ionic molecules, you can not anticipate how many bonds will form just by position on the table
    MOLECULES
  • QUESTIONS