chem mid term 2024 ch 1 and 2

chemistry

science that seeks to understand how matter behaves by studying what atoms and molecules do and explains the properties and behavior of chemicals by helping us understand the molecules that compose them

atoms

come together to form different types of molecules, smallest unit of matter

molecules

two or more atoms formed together

scientific method

a way of learning that emphasized observation and experiment

observations

involvue measuring and observing

hypothesis

tentative explanation of observations

law

summarizes the result of a large number of observations and predicts future ones

theory

a model that gives a deeper explanation for the underlying causes for observation and laws

antoine lavoisier

french chemist who measured mass of substances during combustion and concluded that the mass was same before and after burning (conservation of mass)

mass

measure of quantity of matter within something

conservation of mass

matter is neither created nor destroyed

atomic theory

all matter is made of atoms

scientific data

data from the measurements scientists take as part of their observations

quantification

measurement as part of observation

scientific notation

used for very large and very smal numbers

uncertainty

indicated by the last digit in a number (0.6)

is it a sig fig: trailing zero to the right of a sig fig and after a decimal point (2.0)

yes

is it a sig fig: leading zeros (0.004)

no

is it a sig fig: sandwiched zeros (205)

yes

is it a sig fig: all nonzero numbers (82,3,57,2)

yes

is it a sig fig: trailing zeros before a decimal point (20.1)

yes

is it a sig fig: trailing zeros at the end of a number without decimals (200)

no

when do you round up and down

up: 5 and up

down: 4 and under

rule for rounding sig figs in multiplication and division

round to the same number of sig figs as the number with the fewest sig figs

rule for rounding sig figs in addition and subtraction

round to the same number of decimal places as the quantity with the fewest decimal places