Chemistry and measurements

Length

uses unit of meter (m) in both metric and SI systems

Volume definition

the space occupied by a substance

Volume

Uses the unit Liter (L) in the metric system and uses the unit m³ (cubic meter) in the SI system

Mass definition

A measure of the quantity of material it contains

Mass

Uses the unit gram (g) in the metric system and uses the unit kilogram (kg) in the SI system

Temperature

Uses the celsius (^oc) scale in the metric system and uses the kelvin (k) scale in the SI system

Time

uses unit seconds (s) in both metric & SI systems

Scientific notation definition

used to write very small or large numbers

Measured numbers definition

Are the numbers obtained when you measure a quantity such as your height, weight, or temperature

Estimated number

The final number in your measured number

Significant figures

All non-zero numbers in a measured number are significant

Sandwich zeros

zeros between non-zero numbers are significant even with a decimal involved

Trailing zeros

trailing zeros without a decimal are not significant, with a decimal they are always are significant

Leading zeros

Precede non-zero numbers in a decimal number and are not significant

Significant figures in scientific notation

all digits including zeros in the coefficient are significant

How many significant figures are there in 0.030 m

2

Exact numbers

1. not measured and do not have a limited
   number of significant figures.

2. not used to find the number of significant
   figures in a calculated answer.

3. numbers obtained by counting.
   8 cookies

4. definitions that compare two units.
   1 kg = 1000 g

5. definitions in the same measuring system.

Calculations definitions

answers must have the same number of sig figs as the measured, calculator answers must often be rounded off, and rounding rules are used to obtain the correct number of sig figs

Multiplication and division

use the same number of sig figs as the measurement with the fewest sig figs when rounding

Multiplication rounding example: 110.5 × 0.048 =5.304

5.3

Division rounding example: 4.311/ 0.07=61.586

60

Both multiplication and division example: 2.54×0.0028/0.0105×0.060=11.2889

11

Addition and subtraction

use the same number of decimal places as the measurement with the fewest decimal places when rounding

addition rounding example: 235.05 + 19.6 + 2= 256.65

257

Subtraction rounding example: 58.925-18.2= 40.725

40.7

prefixes and equalities

1kg=1000g, 1g=100cg, 1g=1000mg