Presentation on theme: " What is the definition of significant? How is “Digit” used in this phrase?"— Presentation transcript:
What is the definition of significant? How is “Digit” used in this phrase?
Nonzero digits 654 Zeros between nonzero digits 6042 Zeros to the right of a nonzero digit and to the left of a decimal Zeros to the right of a nonzero digit and to the right of a decimal 0.30
Zeros to the left of decimal in values less than one 0.82 Zeros to the right of decimal and to the left of the first nonzero digit 0.082
Exact Conversion factors are considered to have unlimited significant digits 1000 mm = 1 m Counting numbers have unlimited sig digs 6 doughnuts
Why do we use an elevator? Why is a fax machine an office requirement? Why do we drive a car to work? Which is faster, a whisk or a blender? Why do we use a microwave oven?
Why should you use scientific notation? When should you use scientific notation?
This number represents the number of molecules in one “MOLE” of material. BUT ◦ You have to know the formula of the material. ◦ Write it five times!
Want to write it five more times? Lets write it again like this: ◦ X ◦ This is called scientific notation. ◦ Write this one five times! Which would you rather write? WHY?
What do you notice about this number? ◦ One number to the left of the decimal ◦ This is called scientific notation. ◦ x is NOT scientific notation How do you punch Avogadro's number into a calculator? WARNING, it varies.
x x ◦ These numbers cannot be added as written. ◦ The exponents must be the same in order to add or subtract. = x x = x 10 23
x x 2.37 x 10 22
I’m making omelets for a bunch of people. I need a lot of eggs. What is “a dozen” eggs? Express a dozen eggs in scientific notation: ◦ 1.2 X 10 1 Can you think of two mathematical ways to express TWO dozen eggs (use scientific notation)? ◦ 2 x (1.2 X 10 1 ) ◦ (1.2 X 10 1 ) + (1.2 X 10 1 )
Properly expressed, a SciNot value will have one nonzero digit to the left of the decimal. In converting to SciNot: ◦ ◦ For each place you move the decimal left, increase the exponent by 1 ◦ = X 10 5 (6 Significant Digits) In converting to SciNot: ◦ ◦ For each place you move the decimal right, decrease the exponent by 1 ◦ = X (4 Significant Digits)
The language of chemistry is mathematical and verbal. The typical measurement system of chemistry is the SI system. ◦ Length = Meters (m) ◦ Mass = Grams (g) ◦ Volume = Liters (L) ◦ Temperature = Kelvins (k) or degrees celsius °C ◦ Pressure = Pascals (Pa) or Atmospheres (atm) There are more conversions that we will cover later.
Metric conversions – Remember this acronym: ◦ KHDmdcm g L King Hector Died monday drinking chocolate milk Use this acronym when converting from one metric unit to another metric unit.
Example: ◦ Convert 650 mL (milliliters) to L Liters K H D (L) d c m Since you have to Jump 3 places to the left, move the decimal point 3 digits to the left. You have to move 3 places left = L
Example II: ◦ Convert 7.25 Km (Kilometers) to m (meters) K H D (m) d c m K H D (L) d c m Since you have to Jump 3 places to the right, move the decimal point 3 digits to the right and add a zero. You have to move 3 places right = m
Try! Convert 72.5 g to mg Answer: 72,500 mg Try one more: Convert 26 HL to dL Answer: 26,000 dL
1. Convert 65 mg to g 2. How many Decagrams are in 5 grams? 3. How many kilograms are in 7588 grams? 4. How many deciliters are in 2.7 liters? 5. How many km are in 102,000 cm?