Exam 1 (Chem 130 2024, Streacker)
what do atoms need to decompose - ✔✔electric current
scientific method steps - ✔✔observation
hypothesis
experiment (can either go to theory or back to observation)
theory (model)
prediction
experiment (can go back to theory, theory can be modified as needed)
theory (model) - ✔✔set of tested HYPOTHESES that gives an overall explanation of a natural
phenomenon
- constantly refined or replaced as more information becomes available, limited to human
understanding
natural law - ✔✔a summary of observed (measurable) behavior
- ex: LAW OF CONSERVATION OF MASS in chemistry
law vs theory - ✔✔law - statement on generally observed behavior, summarizes what happens
theory - human inventions, attempts to explain why something happens
science drawbacks - ✔✔focusing on a theory may limit one's ability to see alternative explanations
scientists are humans, and humans have prejudices
science is affected by profit motives, budgets, fads, wars, and religious belief
1.3 - Units of Measurement - ✔✔
important SI units - ✔✔kg (kilogram, mass)
,m (meter, length)
K (kelvin, temperature)
mol (mole, amount of a substance)
s (second, time)
important SI prefixed - ✔✔tera (T) - 10x12
giga (G) - 10x9
mega (M) - 10x6
kilo (K) - 10x3
10x0
deci (d) - 10x-1
centi (c) - 10x-2
milli (m) - 10x-3
micro (u) - 10x-6
nano (n) - 10x-9
mass - ✔✔measure of the resistance of an object to a change in its state of motion - measure of matter
in an object
- measured by the force necessary to give an object a certain acceleration
weight - ✔✔force exerted by gravity on an object
- varies w/ the strength of the GRAVITATIONAL FORCE
ex: 1 kg ball, 4.45 Newtons and 9.81 m/s(2) (on Earth)
- on moon: 0.739 Newtons, 1.62 m/s(2), 0.166 of Earth
1.4 - Uncertainty in Measurement - ✔✔
, certain digits - ✔✔numbers that remain the same regardless of who measures them, and the certain
digits and first uncertain digit are recorded
- uncertainty in the last number is always assumed to me +/-1 unless otherwise indicated
uncertain digits - ✔✔digits that must be estimated and therefore vary
accuracy - ✔✔agreement of a particular value with the TRUE value (how close they are to it)
precision - ✔✔degree of agreement among one/two/several measurements of the same quality (how
close together they are)
random error (intermediate error) - ✔✔measurement that has an equal probability of being low or high
systematic (determinate) error - ✔✔occurs in the same direction each time (always high or always low,
never both)
1.5 - Significant Figures and Calculations - ✔✔
rules for counting sig figs - ✔✔nonzero integers - always count as sig figs
- 1-9
- exact numbers
-> determined by counting, not measuring
-> assumed to have an "infinite number" of sig figs
-> can arise from definitions (such as a dozen)
zeros:
- leading = not significant
- captive = significant
- trailing = not significant
what do atoms need to decompose - ✔✔electric current
scientific method steps - ✔✔observation
hypothesis
experiment (can either go to theory or back to observation)
theory (model)
prediction
experiment (can go back to theory, theory can be modified as needed)
theory (model) - ✔✔set of tested HYPOTHESES that gives an overall explanation of a natural
phenomenon
- constantly refined or replaced as more information becomes available, limited to human
understanding
natural law - ✔✔a summary of observed (measurable) behavior
- ex: LAW OF CONSERVATION OF MASS in chemistry
law vs theory - ✔✔law - statement on generally observed behavior, summarizes what happens
theory - human inventions, attempts to explain why something happens
science drawbacks - ✔✔focusing on a theory may limit one's ability to see alternative explanations
scientists are humans, and humans have prejudices
science is affected by profit motives, budgets, fads, wars, and religious belief
1.3 - Units of Measurement - ✔✔
important SI units - ✔✔kg (kilogram, mass)
,m (meter, length)
K (kelvin, temperature)
mol (mole, amount of a substance)
s (second, time)
important SI prefixed - ✔✔tera (T) - 10x12
giga (G) - 10x9
mega (M) - 10x6
kilo (K) - 10x3
10x0
deci (d) - 10x-1
centi (c) - 10x-2
milli (m) - 10x-3
micro (u) - 10x-6
nano (n) - 10x-9
mass - ✔✔measure of the resistance of an object to a change in its state of motion - measure of matter
in an object
- measured by the force necessary to give an object a certain acceleration
weight - ✔✔force exerted by gravity on an object
- varies w/ the strength of the GRAVITATIONAL FORCE
ex: 1 kg ball, 4.45 Newtons and 9.81 m/s(2) (on Earth)
- on moon: 0.739 Newtons, 1.62 m/s(2), 0.166 of Earth
1.4 - Uncertainty in Measurement - ✔✔
, certain digits - ✔✔numbers that remain the same regardless of who measures them, and the certain
digits and first uncertain digit are recorded
- uncertainty in the last number is always assumed to me +/-1 unless otherwise indicated
uncertain digits - ✔✔digits that must be estimated and therefore vary
accuracy - ✔✔agreement of a particular value with the TRUE value (how close they are to it)
precision - ✔✔degree of agreement among one/two/several measurements of the same quality (how
close together they are)
random error (intermediate error) - ✔✔measurement that has an equal probability of being low or high
systematic (determinate) error - ✔✔occurs in the same direction each time (always high or always low,
never both)
1.5 - Significant Figures and Calculations - ✔✔
rules for counting sig figs - ✔✔nonzero integers - always count as sig figs
- 1-9
- exact numbers
-> determined by counting, not measuring
-> assumed to have an "infinite number" of sig figs
-> can arise from definitions (such as a dozen)
zeros:
- leading = not significant
- captive = significant
- trailing = not significant
