Chemistry Chapter 1: Intro to Matter, Units, and Measurements

Classifying matter

Element vs Compound

Element: cannot be separated further
Compound: 2 or more elements chemically bonded

Homogeneous mixture

Uniform composition throughout

Heterogeneous mixture

Can visually differentiate between the things in the mixture

Physical properties

Characteristics that can be observed with the senses (Boiling point, melting point, color, mass,...)

Chemical properties

Characteristics that can only be observed when undergoing a chemical reaction (flammability, toxicity, conductivity,...)

Extensive physical properties:

Depends on the amount of matter present (mass or volume)

Intensive physical properties

does NOT depend on amount of matter present (hardness or color)

Physical matter change

matter changes form, but not chemical identity (breaking a glass)

Chemical matter changes

reaction occurs which alters chemical identity (boiling an egg)

Law of conservation of mass

matter cannot be created or destroyed during ordinary physical or chemical changes. Therefore the total quantity of matter always remains the same.

Celsius to Fahrenheit conversion

C = 5/9(F-32)

Kelvin to Celsius conversion

K= C+273.15

Density

D= Mass over volume

Density of water

1 g/ml

Unit for solids

g/cm^3

Unit for liquid or gases

g/ml

1 cm^3 is equal to...

1 g/ml

Accuracy

How close the measured value is to the accepted outcome (getting very close to a bullseye once)

Precision

How close the results from repeated measurements or trials are to each other (not getting close to a bullseye necessarily, but all shots are close together)

Uncertain numbers

Numbers with unknown accuracy due to limitations of measuring

Sig Fig rules

1. Leading zeros are never significant
2. Sandwiched zeros are always significant
3a. Trailing zeros are sometimes significant
3b. In a number with a decimal point the zeros ARE significant (120. = 3 sig figs)
3c. in a number without a decimal the zeros are NOT significant
3d. to indicate a trailing zero as significant, add a decimal point or convert to scientific notation
4. All digits included in a number written in scientific notation ARE significant

Sig fig multiplication/division rules

Round answer to the same number of sig figs as the starting number with the least number of sig figs

Sig figs addition/subtraction rules

round the answer to the same number so the answer has the same place value as the least certain starting number (32.11, .159, 13.2, 19.069 - round to the tenths place)