Atoms vs. Ions

1
Atoms vs. Ions

• Recall Atoms protons electrons
• What happens when they are not equal?
• Ions
• atoms or groups of atoms that have a positive or
  negative charge
• Cations
• Positively charged ions
• Loss of electrons
• Anions
• Negatively charged ions
• Gain of electrons

2
What are ionic compounds?

• Electrically neutral compound formed from cations
  and anions
• Usually metals and nonmetals
• Most are crystalline solids at room temperature

3
What is a molecule?

• Monatomic single atoms
• Noble gases (He, Xe)
• Diatomic Molecules
• smallest electrically neutral group of atoms that
  act as a unit of substance
• H2, O2, F2, Br2, I2, N2, Cl2
• Molecular (Covalent) Compounds
• Mostly 2 or more nonmetals
• Low MP, BP
• Examples HCl, H2O

4
Distinguishing between two types of chemical
formulas

• Chemical formula
• Shows kinds and numbers of atoms in the smallest
  representative unit of the substance
• Two Types of Compounds
• Molecular formulas
• Molecular compounds smallest unit
• 7 diatomic molecules
• Elements that commonly exist as molecules
• Formula Units (Ionic Compounds)
• No separate molecular unit, continuous array of
  ions
• Lowest whole number ratio of ions in compound

5
Determining Charge of Ions

• Which elements form what charges?
• Metals tend to lose electrons (positive charges)
• Nonmetals tend to gain electrons (negative
  charges)
• Monatomic ions groups of Periodic table
• Roman numerals for transition metals multiple
  charges
• Examples of ions and charges from P-table
• What is the charge? (S, Pb, Zn, Ar, Br)
• Write symbols for ions, name ions from charges
• Oxide, lead(II), lithium, nitride, cupric,
  fluoride
• Ba2, I-, Ag, Hg2, P3-, Sn4

6
Polyatomic ions

• Group of atoms with a charge
• Tightly bound groups that behave as a unit and
  carry a charge
• Most end in ite, -ate, some exceptions (cyanide,
  ammonium)
• Memorize table 9.3 by Exam (Friday)

7
Writing Formulas and Naming Ionic Compounds

• Binary Ionic Compounds (Formulas)
• 1) 2 elements
• 2) Write charges of ions
• 3) Balance charges
• Lowest ratio
• 3a) Criss-cross method, reduce
• Binary Ionic Compounds (Naming)
• 1) Metal, nonmetal with ide
• 2) Roman Numerals
• Examples potassium nitride, sodium oxide,
  copper(II) sulfide, tin(IV) sulfide, potassium
  chloride, magnesium nitride
• Examples (names) Cs2O, CoI2, AlF3, FeS, CaO,
  Cu2Se

8
Ternary Ionic Compounds

• Contains polyatomic ions
• Use charges, balance with parentheses
• What to do with Polyatomic Ions?
• Remember to treat PI as one unit Install
  Parentheses
• Criss-Cross method
• Examples potassium sulfate, magnesium
  hydroxide, calcium carbonate, tin(IV) dichromate
• Examples LiCN, Sr(H2PO4) 2, (NH4) 2C2O4,
  Fe(ClO3) 3

9
Writing Formulas and Naming Molecular Compounds

• What about formulas for molecular compounds
  ones that are not ionic?
• Rules
• No ionic charges
• Greek prefixes (table 5.5)
• Naming
• 1st element (no mono), 2nd element (-ide)
• Drop vowel when name of 2nd element begins with
  vowel
• Dihydrogen Monoxide
• Website

10
Practice

• N2O, PCl3, AlCl3, SF6
• carbon tetrabromide, dinitrogen tetrahydride,
  boron trichloride, diphosphorus trioxide
• Formula B-I-N-G-O
• Now, youre ready to play!

11
END
12
Experimental Data Led to Two Major Laws

• Law of Definite Proportions
• Samples of any chemical compound, masses of
  elements are always in the same proportions
• Law of Multiple Proportions
• 2 elements forming more than 1 possible compound
• Keep in smallest whole numbers

13
Lab 4 Periodic Properties

• Objectives Measure densities and solubilities to
  look at trends in Periodic table.
• Techniques Volume displacement, solubility
• Data for Silicon on Chalkboard in Lab
• Safety Barium (toxic), Acid GG _at_ all times
• Formal Report CTD reporting, intervention

14
Chemical Bonding and Naming Compounds

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• Origins of Element Names
• Old Element Name Quiz
• Fun Brain Element Quiz
• Latin Names
• Oxyrich Water
• Oxyrich Website
• Refuting Claim

15
Exit Slips

• Atomic Structure
• Draw an atomic model for a Beryllium-9 atom
• Naming Compounds
• Write the correct chemical formula/name for
• Barium Nitrate
• Diphosphorus Pentoxide
• CuCl2
• SeO2
• General Comments
• Anything confusing, Pace, Structure, Lighting,
  etc.

16
Exit Slips 1ST Week feedback

• Congratulations! Youve survived the first week
  (really, the first 3 months) of Chemistry!
• Now, for some feedback on a separate scrap of
  paper, please answer the following anonymously
• 1) How does your current grade match your effort
  grade?
• 2) What do you think of the current structure of
  the class? (Powerpoints, HW, Labs,
  Quizzes/Tests)
• 3) What are some suggestions to make your next 2
  weeks even better? Any other comments?
• Thanks Ill try to take these suggestions into
  account for our last 2 weeks. Great job so far!