1. Significant Figures Any digit that is not zero is significant
1.234 kg significant figures
Zeros between nonzero digits are significant
606 m significant figures
Zeros to the left of the first nonzero digit are not significant
0.08 L significant figure
If a number is greater than 1, then all zeros to the right of the decimal point are significant
2.0 mg significant figures
If a number is less than 1, then only the zeros that are at the end and in the middle of the number are significant
g 3 significant figures

2. How many significant figures are in each of the following measurements?
24 mL
2 significant figures
3001 g
4 significant figures m3
3 significant figures
6.4 x 104 molecules
2 significant figures
560 kg
2 significant figures

3. Significant Figures Addition or Subtraction
The answer cannot have more digits to the right of the decimal
point than any of the original numbers.
89.332
1.1 +
90.432
one significant figure after decimal point
round off to 90.4
3.70
0.7867
two significant figures after decimal point
round off to 0.79

4. Significant Figures Multiplication or Division
The number of significant figures in the result is set by the original number that has the smallest number of significant figures
4.51 x =
= 16.5
3 sig figs
round to
3 sig figs
6.8 ÷ =
= 0.061
2 sig figs
round to
2 sig figs

5. Significant Figures Exact Numbers
Numbers from definitions or numbers of objects are considered
to have an infinite number of significant figures
The average of three measured lengths; 6.64, 6.68 and 6.70? 3
= = 6.67
= 7
Because 3 is an exact number

6. Dimensional Analysis Method of Solving Problems
Determine which unit conversion factor(s) are needed
Carry units through calculation
If all units cancel except for the desired unit(s), then the problem was solved correctly.
How many mL are in 1.63 L?
1 L = 1000 mL 1L
1000 mL
1.63 L x
= 1630 mL 1L
1000 mL
1.63 L x = L2 mL

7. The speed of sound in air is about 343 m/s
The speed of sound in air is about 343 m/s. What is this speed in miles per hour?
meters to miles
seconds to hours
1 mi = 1609 m
1 min = 60 s
1 hour = 60 min
343 m s x
1 mi
1609 m
60 s
1 min x
60 min
1 hour x
= 767 mi
hour

8. Chapter 2 Development of atomic theory Atomic structure Periodic table
Chemical formulas
Naming compounds

9. Dalton’s Atomic Theory (1808)
Elements are composed of extremely small particles called atoms.
All atoms of a given element are identical. The atoms of one element are different from the atoms of all other elements.
Compounds are composed of atoms of more than one element, in specific ratios.
Chemical reactions only involve separation, combination, or rearrangement of atoms. Atoms are not created or destroyed in chemical reactions

10. Law of conservation of mass Law of definite proportions
16 X
8 Y +
8 X2Y
Law of conservation of mass
Law of definite proportions

11. Subatomic particles
Electron
Proton
Neutron

12. Electric and magnetic field off
Magnetic field ON
Electric and magnetic field off
Electric field ON
J.J. Thomson, measured mass/charge of electron
(1906 Nobel Prize in Physics)

14. (Uranium compound)

15. Particles emitted in radioactive decay
a-rays (positively charged)
b-rays (negatively charged; electrons)
g-rays (high energy, uncharged)

16. Atoms’ positive charge is concentrated in the nucleus
(1908 Nobel Prize in Chemistry)
Protons!
Atoms’ positive charge is concentrated in the nucleus

17. Chadwick’s Experiment (1932)
H atoms - 1 proton
He atoms - 2 protons
mass He/mass H should = 2
measured mass He/mass H = 4
Neutrons!
Also shown to reside in the nucleus

18. Rutherford’s Model of the Atom
atomic radius ~ 100 pm = 1 x m
nuclear radius ~ 5 x 10-3 pm = 5 x m

19. X H H (D) H (T) U Atomic number (Z) = number of protons in nucleus
Mass number (A) = number of protons + number of neutrons
= atomic number (Z) + number of neutrons
Isotopes are atoms of the same element (X) with different numbers of neutrons in their nuclei
Mass Number A X
Element Symbol
Atomic Number Z H 1
H (D) 2
H (T) 3 U
235 92
238

20. Group 2A: alkaline earth metals Group 8A: noble gases (rare gases)
The periodic table
Group 1A: alkali metals
Group 2A: alkaline earth metals
Group 7A: halogens
Group 8A: noble gases (rare gases)