Antoine Lavoisier, 1743-1794. Joseph Priestly, 1766-1844. Marie Curie, 1867-1934. Dmitri Mendeleev, 1834-1907. John Dalton, 1766-1844. What is Matter? Matter : Anything that occupies space and has mass Energy: Ability to do work, accomplish a change Physical States of Matter
Joseph Priestly, 1766-1844
Marie Curie, 1867-1934
Dmitri Mendeleev, 1834-1907
John Dalton, 1766-1844
Matter: Anything that occupies space and has mass
Energy: Ability to do work, accomplish a change
Physical States of Matter
Gas: Indefinite volume, indefinite shape, particles far away from each other
Liquid: Definite volume, indefinite shape, particles closer together than in gas
Solid: Definite volume, definite shape, particles close to each other
Property: Characteristic of a substance
Each substance has a unique set of properties identifying it from other substances.
Intensive Properties: Properties that do not depend on quantity of substance
Examples: boiling point, density
Extensive Properties: Properties that depend on or vary with the quantity of substance
Examples: mass, volume
Physical Properties: Properties of matter that can be observed without changing the composition or identity of a substance
Example: Size, physical state
Chemical Properties: Properties that matter demonstrates when attempts are made to change it into new substances, as a result of chemical reactions
Example: Burning, rusting
Physical Changes: Changes matter undergoes without changing composition
Chemical Changes: Changes matter undergoes that involve changes in composition; a conversion of reactants to products
Example: Burning match; fruit ripening
Measurement: Determination of dimensions, capacity, quantity or extent of something; represented by both a number and a unit
Examples: Mass, length, volume, energy, density, specific gravity, temperature
Mass vs. Weight
Mass: A measurement of the amount of matter in an object
Weight: A measurement of the gravitational force acting on an object
Density: mass divided by volume; d = m/v
Specific gravity: density of a substance relative to the density of water
Fahrenheit: -459oF (absolute zero) - 212oF (water boils)
Celsius: -273oC (absolute zero) - 100oC (water boils)
Kelvin: 0K (absolute zero) - 373 K (water boils)
oC = 5/9 (Fo - 32) oF = 9/5 (oC) +32
Converting Celsius and Kelvin:
oC = K - 273 K = oC + 273
Scientific Notation and Significant Figures
Scientific notation: a shorthand way of representing very small or very large numbers
Examples: 3 x 102, 2.5 x 10-4
Practice with Scientific Notation moved from its original position in the number to its position when the number is written in scientific notation
50,000 = 5.0 x 104 300 =
.00045 = 4.5 x 10-4 .0005 =
3.00 x 102
5 x 10-4
4 sig. figs.
5 sig. figs.
4 sig. figs.
1 sig. fig.
2 sig. figs.
4 sig. figs.
Calculations and Significant Figures moved from its original position in the number to its position when the number is written in scientific notation
Answers obtained by calculations cannot contain more certainty (significant figures) than the least certain measurement used in the calculation
Multiplication/Division: The answers from these calculations must contain the same number of significant figures as the quantity with the fewest significant figures used in the calculation
Example: 4.95 x 12.10 = 59.895
Round to how many sig. figs.?
Addition/Subtraction: moved from its original position in the number to its position when the number is written in scientific notation The answers from these calculations must contain the same number of places to the right of the decimal point as the quantity in the calculation that has the fewest number of places to the right of the decimal
Example: 1.9 + 18.65 = 20.55
How many sig. figs.required?
Rounding off: a way reducing the number of significant digits to follow the above rules
Determine the appropriate number of significant figures; any and all digits after this one will be dropped.
If the number to be dropped is 5 or greater, all the nonsignificant figures are dropped and the last significant figure is increased by 1
If the number to be dropped is less than 5, all nonsignificant figures are dropped and the last significant figure remains unchanged
Exact (counted) numbers: numbers determined by definition or counting
Example: 60 minutes per hour, 12 items = 1 dozen
Inexact (measured) numbers: numbers determined by measurement, by using a measuring device
Example: height = 1.5 meters, time elapsed = 2 minutes
Classify each of the following as an exact or a inexact number.
A. A field is 100 meters long.
B. There are 12 inches in 1 foot.
C. The current temperature is 20o Celsius.
D. There are 6 hats in the closet.
Calculating Percentages numbers
percent = “per hundred”
% = (part/total) x 100
Example: 50 students in a class, 10 are left-handed. What percentage of students are lefties?
% lefties = (# lefties/total students) x 100
= 10/50 x 100
= .2 x 100
Accuracy vs. Precision arithmetic to produce the final answer
Error: difference between true value and our measurement
Accuracy: degree of agreement between true value and measured value
Uncertainty: degree of doubt in a measurement
Precision: degree of agreement between replicated measurements