Chemistry Ch. R

Measurement, Unit conversions, dimensional analysis, density+derived relationships, temperature, sig figs, classification of matter, SI units, unit prefix

Significant figures

sig figs (communicate the uncertainty of the measurement) are: nonzero digits, leading zeros, captive zeros, and trailing zeros

Exact numvers

numbers with infinite significant figures that are counted or defined, such as those in a mathematical formula or a defined measurement like 100 centimeters in a meter.

Sig fig. rules in math operations

Multiplication/Division: answer has the same # of sig figs as the # in the calculation w/ the least sig figs
Addition/subtraction: answer has same # of decimal places as # in calculation w/ the least of decimal places

Unit prefix: femto

Symbol: f
10^-15

Unit prefix: pico

symbol: p

10^-12

unit prefix: nano

symbol: n

10^-9

unit prefix: micro

symbol: µ
10^-6

unit prefix: milli

symbol: m
10^-3

unit prefix: centi

symbol: c
10^-2

unit prefix: deci

symbol: d
10^-1

unit prefix: kilo

symbol: k
10³

unit prefix: mega

symbol: M
10^6

unit prefix: giga

symbol: G
10^9

unit prefix: tera

symbol: T
10^12

empiricism

knowledge based on observation/measurement

Dalton’s atomic theory postulates

1. each element consists of indestructible atoms

2. atoms of an element are identical (have identical properties)

3. compounds combine atoms

4. chemical reactions involve combining, separating, or rearranging atoms (not change atoms)

Law of conservation of mass

total mass remains constant during a chemical reaction bc atoms only rearrange

law of definite porportions

a given compound always contains the exact same relative mass and # of atoms of each element

law of multiple proportions

if 2 elements form more than one compound, the mass ratios are small whole numbers

SI Unit: mass

kilogram (kg)

SI unit: length

meter(m)

SI unit: time

second(s)

SI unit: temperature

kelvin(K)

SI unit: electric current

ampere(A)

SI unit: amount of substance

mole (mol)

SI unit: luminous intensity

candela(cd)

element: H

hydrogen

element: He

helium

element Li

lithium

element Be

Beryllum

element Na

sodium

element Mg

magnesium

element B

boron

element C

carbon

element N

nitrogen

element O

oxygen

element F

flourine

element Ne

neon

element Al

aluminum

element Si

silicone

element P

phosphorus

element S

sulfer

element Cl

chlorine

element Ar

argon

element K

Potassium

element Ca

calcium

element Sc

scandium

element Ti

titanium

element V

vanadium

element Cr

chromium

element Mn

manganese

element Fe

iron

element Co

cobalt

element Ni

nickel

element Cu

copper

element Zn

zinc

element Ga

galium

element Ge

germanium

element As

arsenic

element Se

selenium

element Br

bromine

element Kr

krypton

element Rb

rubidium

element Sr

strontium

a measurement has..

1. a unit

2. a value

3. an uncertainty

density units

g/mL or g/L or g/cm³

atomic mass unit

amu

m=dm

1m=10dm

dm=cm

1dm=10cm

lbs=kg

2.2lbs=1kg

mi=km

1mi=1.6km

kg=g

1kg=1000g

dm³ =L

1dm³ =1L

cm³ =mL

1cm³ =1mL

dm³ =m³

1000dm³ =1m³

mi=ft

1mi= 5280ft

ft=in

1ft=12in

in=cm

1in=2.54cm

joules

J

watts or energy/power

W or Jouls/second

W= J/s

1W=1 J/s

cal

calorie

cal=J

1kCal=4184J

ton=lbs

1ton=2000lbs

L=cm³

1L=1000cm³

^oC to K

K= C + 273.15

C to F

F= C x 5/9 +32F

F to C

C= 5/9 (F -32F)

Density definition

mass of a substance per unit volume

what is density used for

identifying substances, separating liquids

Density) volume relationship

1cm³ (solids)= 1mL (liquids, gases)

density conversion to know

water density) 1g/mL=1g/cm³