Renee Y. Becker
Valencia Community College
CHM 1045
1

Dalton’s Atomic Theory
•
Elements are made of tiny particles called atoms .
•
Each element is characterized by the mass of its atoms. Atoms of the same element have the same mass, but atoms of different elements have different masses.
•
Chemical reactions only rearrange the way atoms are combined; the atoms themselves are unchanged.
2

The Structure of Atoms
•
Cathode-Ray Tube (Thomson, 1856–1940):
Cathode rays consist of tiny negatively charged particles, now called electrons.
3

The Structure of Atoms
•
Deflection of electron depends on three factors:
–
Strength of electric or magnetic field
–
Size of negative charge on electron
–
Mass of the electron
• Thomson calculated the electron’s charge to mass ratio as 1.758820 x 10 8 Coulombs per gram.
4

The Structure of Atoms
•
Oil Drop Experiment (Millikan, 1868–1953):
Applied a voltage to oppose the downward fall of charged drops and suspend them.
•
Voltage on plates place
1.602176 x 10 -19 C of charge on each oil drop.
•
Millikan calculated the electron’s mass as
9.109382 x 10 -28 grams.
5

The Structure of Atoms
•
Discovery of Nucleus: Rutherford irradiated gold foil with a beam of alpha particles to search for positive charged particles. Most of the particles passed through but some were deflected at large angles, why?
6

The Structure of Atoms
7

Periods: Seven horizontal rows
Groups: 18 vertical columns, based on similar chemical properties
8

Periodic Table
9

The Structure of Atoms
Standard Format
10

The Structure of Atoms
•
Isotopes: Atoms with identical atomic numbers, but different mass numbers.
•
Average Isotopic Mass: A weighted average of the isotopic masses of an element’s naturally occurring isotopes.
•
Atomic Mass: A weighted average of the isotopic masses of an element’s naturally occurring isotopes.
11

Example 1: Periodic Table
What are the atomic numbers for the following elements?
1) Copper
2) Sodium
3) Sulfur
4) Oxygen
12

Example 2: Periodic Table
What are the atomic masses for the following elements?
1) Iron
2) Magnesium
3) Bromine
4) Xenon
13

Example 3: Periodic Table
What are the mass numbers for the following elements?
1) Chlorine
2) Nitrogen
3) Carbon
4) Zinc
14

Example 4: The Structure of Atoms
•
The isotope is used medically for
34
Se diagnosis of pancreatic disorders. How many protons, neutrons, and electrons does an atom of have?
34
Se
15

Example 5: The Structure of Atoms
•
An atom of element X contains 47 protons and 62 neutrons. Identify the element, and write the symbol for the isotope in the standard format.
16

Example 6: The Structure of Atoms
•
Chlorine has two naturally occurring isotopes:
35
17
Cl with an abundance of 75.77% and an isotopic
37 mass of 34.969 amu, and with an abundance
17
Cl of 24.23% and an isotopic mass of 36.966 amu.
What is the atomic mass of chlorine?
17

Element
P
Na +
S 2-
Electrons
Example 7: Periodic Table
Protons Neutrons
18

Atoms, Molecules, and Ions
•
Covalent Bonding (Molecules): The most common type of chemical bond is formed when two atoms share some of their electrons.
(non-metal -- non-metal)
19

Atoms, Molecules, and Ions
Naming Binary Molecular Compounds:
•
The more cationlike element uses its elemental name.
•
The more anionlike element substitutes the second half of its elemental name with
–ide
.
•
Use the Greek prefixes to express the number of each element present.
20

Atoms, Molecules, and Ions
21

Greek Prefixes
Nona-
Deca-
9
10
22

Example 8: Atoms, Molecules, and Ions
Examples:
CO carbon monoxide
CO
2
SF
4 carbon dioxide sulfur tetrafluoride
Name:
NCl
3
P
4
O
6
S
2
F
2
Write formulas:
Disulfur dichloride
Iodine monochloride
Nitrogen trioxide
23

Atoms, Molecules, and Ions
•
Ionic Bonding (Ionic Solids): These are formed by a transfer of one or more electrons from one atom to another. (metal -- non-metal)
24

Example 9
Which of the following drawings represents an ionic compound? Molecular compound?
25

Atoms, Molecules, and Ions
Naming Binary Ionic Compounds:
•
Identify the positive ion and then the negative ion.
•
The positive ion uses its elemental name.
•
The negative ion substitutes the second half of its elemental name with
–ide
.
•
Do not use Greek prefixes such as mono– , di– , or tri– .
•
Use roman numerals for transition metals
26

Atoms, Molecules, and Ions
27

Atoms, Molecules, and Ions
28

1. NaCl
2. MgS
3. Ba
3
N
2
4. CaO
5. K
2
S
6. FeCl
2
7. FeCl
3
8. CrO
2
9. ZnCl
2
10. V
2
O
3
Example 10: Name
29

1. Calcium chloride
2. Copper (II) sulfide
3. Sodium nitride
4. Silver bromide
Example 11: Draw
5. Nickel (II) phosphide
6. Cesium oxide
7. Strontium iodide
8. Cobalt (I) sulfide
30

Atoms, Molecules, and Ions
31

Atoms, Molecules, and Ions
•
Naming Ionic Compounds Containing Polyatomic
Ions :
–
Same as binary ionic compounds
–
But use the name provided for the polyatomic ion
32

Example 12: Atoms, Molecules, and Ions
•
Examples
–
CaCO
3
–
FeCrO
4
–
KOH
Name:
Ba
3
(PO
4
)
2
Na
2
SO
4
Sn(ClO
4
)
4
Calcium carbonate
Iron(II) chromate
Potassium hydroxide
Write Formulas:
Iron(II) permanganate
Cesium nitrate
Zinc acetate
33

Example 13:
Which of the following is a covalent compound?
1) NaCl
2) NaOH
3) H
2
O
4) AlCl
3
34

Atoms, Molecules, and Ions
Acid: A substance that provides H + ions in H
2
O
Base: A substance that provides OH in H
2
O
Oxoacid: Contain oxygen and hydrogen and another element
35

Atoms, Molecules, and Ions
When acid is dissolved in water gives one or more H + and a polyatomic oxoanion, (has to have
(aq)
)
Name of acid is based on the oxoanion
36

Atoms, Molecules, and Ions
37

Example 14: Atoms, Molecules, and Ions
Name the following acids:
(a) HBrO
3
(aq)
(b) HCN (aq)
(c) HIO
3
(aq)
(d) HMnO
4
(aq)
(e) H
2
CrO
4
(aq)
38

Balancing Chemical Equations
•
A balanced chemical equation represents the conversion of the reactants to products such that the number of atoms of each element is conserved.
Calcium carbonate
 calcium oxide + carbon dioxide
CaCO
3
(s)

CaO(s) + CO
2
(g)
39

Balancing Chemical Equations
•
Balancing Equations: write unbalanced equation
A
2
+ B
2

A
2
B
•
Use coefficients to indicate how many formula units are required to balance the equation:
A
2
+ B
2

A
2
B
40

Balancing Chemical Equations
•
Method 1 (suggested)
–
Balance those atoms which occur in only one compound on each side
–
Balance remaining atoms
–
Reduce coefficients to smallest whole integers
–
Check your answer
41

Balancing Chemical Equations
•
Method 2
–
Identify most complex compound
–
Balance this compound by placing 1 before it
–
Balance remaining compounds using fractions
–
Multiply fractions to obtain integers
42

Example 15: Balancing Chemical Equations
•
Balance the following equations
C
6
H
12
O
6

C
2
H
6
O + CO
2
Fe + O
2

Fe
2
O
3
NH
3
+ Cl
2

N
2
H
4
+ NH
4
Cl
KClO
3
+ C
12
H
22
O
11

KCl + CO
2
+ H
2
O
43