COMPOSITION OF POLLUTION - FREE GROUND LEVEL AIR

Nitrogen 

78.08%

Oxygen 

20.95%

Carbon Dioxide

0.03%

 

COMPOSITION OF UNIVERSE

COMPOSITION OF EARTH

         

Hydrogen

60.40%

  

Iron 

35.4%

Helium 

36.56%

  

Oxygen 

 27.8%

Oxygen

 0.96%

  

 Magnesium

 17.0%

 

Carbon

 0.30%

  

 Silicon

 12.6%

 

ELEMENTS

90 Naturally occurring
19 Synthesized
109 TOTAL

ATOM Chapter 3

What is it?

Def: The smallest particle still having the characteristics of an element. It is made up of smaller particles: electrons, protons, and neutrons.

Simplest atom is H (hydrogen).

 

electron

proton

 

PROTON

1. Positive charge
2. "Weighs" 1 amu (atomic mass unit)
     1 lb. = 273 x 1024 amu
3. The number of protons is the atomic number of an element.
4. The number of protons tells you what the element is.
5.  What element has 6 protons?
6.  How many protons in the element nitrogen (N)?

ELECTRON
1. Negative charge
2. 1835 electrons weigh 1 amu.
3. Responsible for chemical bonds

NEUTRON
1. No net charge
2. Weighs 1 amu

ATOMIC WEIGHTS

To get the atomic weight you add the number of protons and neutrons. When the protons and neutrons are considered as a unit, they are referred to as "nucleons".

Def. Average weight of all the atoms of an element.

Hydrogen has 1 proton and 1 electron, totaling 1 amu.

Deuterium has 1 proton (1 amu), 1 neutron (1 amu),
               and 1 electron, totaling 2 amu.

Tritium has 1 proton (1 amu), 2 neutrons (2 amu), and 1 electron, totaling 3 amu.

ISOTOPES

Def: Atoms of the same element that have the same
       atomic number but have different mass numbers.

       The isotopes of an element all have the same number of protons but a different number of neutrons.

       Hydrogen, deuterium and tritium are isotopes.

       Tritium is radioactive.

ISOTOPES OF URANIUM

238                   235
    U             U
 92                    92

What does the 92 mean? What does the 238 mean?

Summary:

Atomic number
Atomic weights

ISOTOPES

A
  X             X = symbol of the element
Z                      Z = number of protons
                        A = mass number (number of protons and neutrons)

                    1H = hydrogen      2H = deuterium        3H = tritium
                    1                                    1                                       1

ATOMIC STRUCTURE

2 electrons can fit on the first level

 

 

8 electrons on the second

Atoms are happy when a shell or level is complete - will enter into reaction just to get the number of electrons for that shell.

 

IONS

When an atom does not have the same number of electrons and protons, it has a charge. This is an ion.

If an ion had 11 protons and 10 electrons, it would be a positive ion. These are called cations.

What element has 11 protons?

If an ion had 17 protons and 18 electrons, it would be a negative ion. These are called anions.

What element has 17 protons?

Atoms and Ions

Atoms have no net charge. They are neutral.

Ions have a charge, either positive or negative.

A positive ion has more protons than electrons. CATION

A negative ion has more electrons than protons. ANION

The ion of an atom has very different chemical properties than the atom or molecule. Sodium is a soft metal, which reacts with water and gives explosive hydrogen.

The sodium ion is half of table salt NaCl, which dissolves in water and is needed for human life.

                                        23Na                 23Na+

# protons     

# neutrons

# electrons

 

Problems

Chemical Symbol

#Protons

# Neutrons

#Electrons

Charge

Name
           

4020Ca++

          

19078Pt

          

22387Fr

          

12953I-

          

4He

          
   

7

6

  

Carbon
   

14

15

  

0
   

18

18

  

Sulfur ion
   

30

24

  

Iron ion
   

118

  

+3

Gold ion
 

9

9

  

-1

  

Wednesday, March 21, 2007 01:28:03 PM