1. Atoms, Molecules, and Ions
General Chemistry I – Chapter 2

2. Objectives 1.0 Define key terms and concepts
1.10 Demonstrate an understanding of the Law of Conservation of Matter, the Law of Multiple Proportions, and the Law of Definite Proportions.
1.11 Describe the structure of an atom using atomic theory.
1.12 Recognize and utilize trends on the periodic table.
1.13 Recognize the difference between covalent and ionic compounds.
1.14 Name chemical compounds and write their formulas.

3. Law of Conservation of Mass
The mass of a reaction conducted in a closed system cannot be changed.
While matter cannot be created or destroyed, it can be rearranged.
HgO + heat  Hg + O2
The mass of the reactants must equal the mass of the products.

4. Law of Definite Proportions
A compound always contains the same elements in certain definite proportions and in no other combinations (H2O and H2O2)
Also states that compounds have constant properties

5. The Law of Multiple Proportions
Different elements can be combined in multiple proportions to make different compounds.
H2O and H2O2
NO, N2O, and NO2
CO and CO2

6. History of the Atom
Democritus and the first theory of the atom/matter.
Dalton’s Atomic Theory
Thompson and the Plum Pudding Model
Rutherford’s Gold Foil Experiment
Bohr’s Model of the Atom
Quantum Theory of the Atom

7. Dalton’s Atomic Theory (1805)
Every element is made up of tiny particles called atoms.
All atoms of a given element are identical to one another and different for atoms of other elements.
Atoms of two or more different elements combine to form compounds. A particular compound is always made up of some kinds of atoms and the same number of each kind of atom.
A chemical reaction involves the rearrangement, separation, or combination of atoms. Atoms are never created or destroyed during a chemical reaction.

8. Thomson Cathode Ray Tube (1897)

9. Thomson Cathode Ray Tube (1897)

10. Rutherford’s Gold Foil Experiment (1911)

11. Bohr Model of the Atom (1913)

12. Quantum Model of the Atom (1926)

13. What Are Your Questions?

14. Cl Atomic Number and Mass 17 35.453 Chlorine Atomic Number
Element Symbol
Element Name
35.453
Atomic Mass

15. Isotopes
Atoms of the same element that have different number of neutrons.
The number of protons is ALWAYS the same.

16. Isotopes

17. Radioactivity
The spontaneous emission of radiation from certain unstable elements
Rontgen and The Curies
Half-Life
the amount of time it takes for half of a radioactive substance to decay

18. Types of Radioactivity
Alpha (α)
The least energetic of the three types of radioactivity
Made of up positively charged particles
Identical to the nucleus of a helium atom
Symbolized as He2+
Beta (β)
The second most energetic form of radioactivity
Made up of negatively charged particles (electrons)
Symbolized as e-
Gamma (γ)
A form of electromagnetic radiation
The most energetic and penetrating of all radiation
Has medical applications

19. Calculating Atomic Mass
Calculate the Atomic Mass of Cl.
35Cl = amu with % abundance
37Cl = amu with % abundance

20. Atomic Number and Mass Name of Element Symbol Atomic Number
Mass Number
# of Protons
# of Neutrons
# of Electrons P 32
44 
101 12
12 
 Silicon 15
 82
125

21. What Are Your Questions?

22. Origins of the Elements
The most abundant element in the
universe is Hydrogen followed by Helium
Hydrogen was produced by stars in the universe and the fusion of two Hydrogen atoms formed Helium.
73% of the universe is Hydrogen, 25% is Helium, and about 2% is comprised of the heavier elements.
The heavier elements are created in older stars such as Red Giants and White Dwarfs due to the high pressure allowing for the fusion of He and C to make Oxygen and so on.

23. Elements and Symbols
Chemical Symbol
One- or two- letter abbreviation for a chemical element

24. Elemental Symbols to Memorize
Please learn the elemental names/symbols for the first 20 elements and Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Br, I, Kr, Xe, Ag, Sn, Au, Hg, and Pb

25. The Periodic Table

26. The Periodic Table

27. The Periodic Table: Groups
Alkali Metals
Soft, shiny metals that are good conductors of electricity. React violently with water.
Alkaline Earth Metals
Shiny like alkali metals
but not as reactive.

28. The Periodic Table: Groups
Halogens
Strongly reactive and form compounds with most elements
Noble Gases
Unreactive and seldom found in combination with other elements
Halogens
Strongly reactive and form compounds with most elements
Noble Gases
Unreactive and seldom found in combination with other elements

29. Metals, Nonmetals, and Metalloids
Shiny solids that are very malleable and ductile and good conductors of heat and electricity.
Nonmetals
Not very shiny, malleable or ductile and are poor conductors of heat and electricity
Metalloids
Semi-metals

30. Molecules and Ions Molecule Diatomic Molecule Diatomic Element
A combination of at least two atoms held in a definite arrangement by chemical forces, or bonds.
Diatomic Molecule
Contains two atoms
Diatomic Element
Molecule that contains two atoms of the same element
H, N, O, F, Cl, Br, I
Polyatomic Molecule
A molecule containing more than two atoms

31. Molecules and Ions Ion Monoatomic Ions Polyatomic Ions
An atom or group of atoms that possesses a charge
Cation
Positively charged molecule
Anion
Negatively charged molecule
Monoatomic Ions
Contains only one atom, or ion
Polyatomic Ions
Contains many atoms, or ions

32. Variable Oxidation States
Oxidation Numbers
Transition Metals
Variable Oxidation States

33. Charge Balance and Writing Formulas
Chemical Formula (molecular formula)
Indicates the elements and number of elements that make up a compound
Write the element with the charge and then cross it over and down

34. Write the chemical formula formed when the following elements bond.
Na and Cl
Ca and Br
H and O
C and H
N and I

35. Nomenclature Ionic Compounds Covalent Compounds (Molecular)
Formed between metals and nonmetals
Covalent Compounds (Molecular)
Formed between two nonmetals

36. Determine whether the following compounds are covalent or ionic.
Na and Cl
Ca and Br
H and O
C and H
N and I

37. Naming Ionic Compounds
The name of the cation is the name of the element.
Examples
Na+ = sodium ion
Mg2+ = magnesium ion
The name of the anion is the root name of the element plus the suffix –ide.
Cl- = chloride ion
O2- = oxide ion

38. Naming Ionic Compounds
To name the compounds of simple binary ionic compounds (those containing only two elements), simply name the ions.
Examples
NaCl = sodium chloride
MgO = magnesium oxide

39. Name the following ionic compounds.
Li2O
NaBr
AlBr3
BaO
Na2S

40. Write the Formula for the Following Ionic Compounds
Sodium Iodide
Aluminum Chloride
Lithium Bromide
Hydrogen Fluoride
Magnesium Sulfide
Sodium Oxide

41. Naming Ionic Compounds
Transition metals can have more than one positive ion form in an ionic bond
Roman numerals are used the in naming of these compounds to identify the metal’s charge
Examples
CuCl2 = Copper (II) Chloride
SnO2 = Tin (IV) Oxide

42. Naming Ionic Compounds
Modern Name
Latin Name
Symbol
Symbol with charge
Traditional Name
Stock System Name
Copper
Cuprum Cu
Cu+1
Cuprous
Copper (I)
Cu+2
Cupric
Copper (II)
Iron
Ferrum Fe
Fe+2
Ferrous
Iron (II)
Fe+3
Ferric
Iron (III)
Mercury
Hydrargyrum Hg
Hg+1
Mercurous
Mercury (I)
Hg+2
Mercuric
Mercury (II)
Lead
Plumbum Pb
Pb+2
Plumbous
Lead (II)
Pb+4
Plumbic
Lead (IV)
Tin
Stannum Sn
Sn+2
Stannous
Tin (II)
Sn+4
Stannic
Tin (IV)

43. Name/write the chemical formula for the following ionic compounds
CuCl
FeBr3
MnO
PbS2
Iron (II) Chloride
Copper (II) Oxide
Nickel (II) Phosphide
Mercury (I) Chloride

44. Polyatomic Ions Polyatomic Ion
A group of atoms that has an electrical charge
The charge is shared among the atoms that form the polyatomic ion
-ate means more oxygens
Phosphate, PO43-
-ite means fewer oxygens
Phosphite, PO33-

45. Naming Polyatomic Ions
Writing Formulas
Follows same rules as for ionic bonding
Total charge of molecule always equals zero
Naming
Write positive metal first followed by name of polyatomic ion
Examples
H2SO4 Hydrogen Sulfate
Ca2CO3 Calcium Carbonate

46. Name the following ionic compounds containing a polyatomic ion.
Potassium Sulfate
Sodium Carbonate
Copper (II) Nitrate
Potassium Permanganate
Manganese (II) Sulfite

47. Write the Formula for the Following Ionic Compounds.
NaHCO3
NH4C2H3O2
K2CrO4
Ca(CN)2
Fe3(PO4)2

48. Naming Covalent Compounds
Similar to ionic naming; however, a prefix is used to identify the number of each element present in the name
Examples
CH4 = carbon tetrahydride
NO2 = nitrogen dioxide

49. Name the following covalent compounds.
CS2
PCl3
P2O5
N2O4
Cl2O

50. Write the formula for the following covalent compounds.
Iodine Pentafluoride
Tetraphosphorus hexoxide
Dinitrogen pentoxide
Carbon Tetrahydride
Dihydrogen oxide

51. Naming Ionic and Covalent Compounds
Is the compound Ionic or Covalent?
Does the Compound have a Polyatomic Ion?
Name using the polyatomic rules.
Name the metal cation followed by the nonmetal anion ending in –ide.
Name using the di, tri, tetra prefixes
Ionic
Covalent
Yes No
Does the compound contain a transition metal?
Yes No
Name using Roman Numerals to express the charge on the transition metal.
No further steps necessary.

52. Acids and Bases Acid Base
A substance that produces hydrogen ion when dissolved in water
The hydrogen is written first in the chemical formula
Base
A substance that produces hydroxide ion when dissolved in water
The hydroxide is written second in the chemical formula

53. Naming Acids and Bases
For an acid containing a hydrogen and an anion: use the prefix hydro and change the –ide of the nonmetal to –ic and add the word acid.
Example
HCl = Hydrogen Chloride is Hydrochloric Acid
For an acid containing a polyatomic ion, name the anion after the polyatomic ion, changing the –ate to –ic or the –ite to –ous and add the word acid.
HNO3 = Hydrogen Nitrate is Nitric Acid
HNO2 = Hydrogen Nitrite is Nitrous Acid
Name a base as you would a polyatomic ion
Ca(OH)2  Calcium Hydroxide
NaOH  Sodium Hydroxide

54. Naming Acids and Bases H2SO4 HF LiOH HBr H3PO4 Acetic acid
Carbonic Acid
Phophorus Acid
Hydroiodic Acid
Magnesium Hydroxide

55. Hydrates Compounds that have water incorporated into the structure
Name the compound as usual, but indicate the number of water molecules present using a numeric prefix
MgCl2 x 7H2O = Magnesium Chloride heptahydrate
CuSO4 x 5H2O
CuCl2 x 2H2O
Cobalt (II) Chloride Hexahydrate

56. What Are Your Questions?