Chemistry Unit 1 Test: Basic Science & Measurements

scientific notation

communicates large numbers efficiently

1) has two parts: coefficient and power of 10

scientific notation coefficient

the number being multiplied by a power of 10 in scientific notation

1) must be lesser than 10 but greater than 1

scientific notation power of 10

the number being multiplied by the coefficient in scientific notation

1) has positive and negative powers (+ → move to right; - → move to left)

4) number of places to the left or right = the exponent

theory

A mega-hypothesis contributed to by multiple people for decades

1) ex: cell theory

conclusion

the answer to one hypothesis in one experiment

1) ex: I am not alergic to shrimp

types of observations

1) qualitative

2) quantitative

qualitative observations

descriptions of non-number qualities (color, opacity, etc.)

quantitative observations

numbers and measurements

measurements

numbers and units

Scientific Notation on Calculator

coefficient + E + power of 10 exponent

exponent rules

• 10^a x 10^b = 10^a+b

• 10^a/10^b = 10^a-b

coefficient x power of 10 exponent relationship

= like a seesaw

1) if one goes up, the other goes down

scientific method

1) observations

2) hypothesis

3) experiment

4) conclusion

significant figures

all certain digits + one estimated digit

1) communicate the tool/precision with which we’re working

valid significant figures

1) all digits of scientific notation coefficient

2) nonzero digits

3) captive zeros

4) trailing zeros iff the number contains a decimal

captive zeros

zeros in between nonzero digits

trailing zeros (significance)

trailing zeros are significant iff number contains a decimal

1) so if you need certain zeros to count, use a decimal

2) ex: 100. has 3 sig figs

leading zeros

are never significant

exact numbers

definitions and #’s counted by “hand”

1) not a measurement

2) infinite number of significant figures because nothing is uncertain

2) ex: there are 2 dogs

sig fig addition/multiplication

always limited by least precise measurement

sig fig multiplication

product has same number of sig figs as # with fewest sig figs

sig fig addition

sum goes to the same sig fig place value as least precise measurement

precision

how detailed was the equipment?

accuracy

how close were you to measuring something’s true value?

1) = measured in percent error

percent error formula

(| true value - estimated value|/true value) x 100%

1) cannot be negative because of absolute value signs

Metric conversion rates

• M = mega = 10⁶m

• k = kilo = 10³m

• root unit = 10⁰

• d = deci = 10^-1

• c = centi = 10^-2

• m = milli = 10^-3

• µ = micro = 10^-6

• n = nano = 10^-12

STUDY

LABS

Potential Energy Formula

PE = (mass)(g)(height) = Activation Energy in Joules