Significant figures

ex.

.02040

30.0

800

• leading zeros dont count
• zeros in between do count
• trailing zeros count only if there is a decimal point

.02040- 4 sig figs

30.0 - 3 sig figs

800-1 sig fig

10^-3

[image]Beryllium,magnesium, calcium

• Atomic#= Protons
• if # of electrons > # of protons - the element is negative the difference
• Mass= neutrons + protons

ex. 15 N^-3

mass?

how many protons?

electrons?

neutrons?

mass=15

Protons=7

electrons=10

neutrons= 8

Naming (I)

-(anion+anion)or (anion+cation within 1A,2A,3A,Zn,Cd,Ag)

add [prefix+name][prefix+ide] 

prefix?: 1,2,3,4,5,6,7,8,9,10

ex. name Cl203

Prefix:

mono,di,tri,tetra,penta,hexa,hepta,octa,nona,deci

ex.dichlorine trioxide

Naming(II)

• If the compound includes any transitional metals than roman Numerals are used to represent the charge of transitional metal.

ex. Cu3 and Cr2S3

Cu3     Copper (III) ion

Cr2S3  Chromium (III) Sulfide

Empiracle Formula

ex. 35.57% Phosphorus 64.43% Sulfur

?molP=35.57gP(1mol/30.97g) =1.149molP

?molS=64.43gS(1mol/32.07g)=2.009molS

P1.149 S2.009

 /1.149  /1.149

=P1S1.75

4(P1S1.75)

P4S7

Steps

-find mol ratio using atomic mass

-multiply both ratios by smallest ratio

-if #s don't come out even then multiply by largest number to make them even.

Limiting reactant

ex. ?gC02 when 18gC3H8O3 combine w/ 24gO2

• found out how many grams of both C3H803 and 02 make CO2
• the one who makes less is the limiting reactant

ex. ?gC02=18gC3H8O3

     ?gCO2=24gO2

Dilution

M1*V1=M2*V2

Molarity

/consentration

M= #mols

     1L

ex. If you have .233M how many gram of AlCNO3I3 poor out 475ml

?g=475ml 1L          .223mol 213.01g

                1000ml  1L          1mol

=22.6g

-now how many ml if you have 8.5g and .223M

?ml=8.5g 1mol       1L     1000ml

               213.01g  .223    1L

=180ml