COMPOSITION OF POLLUTION - FREE GROUND LEVEL AIR
COMPOSITION OF UNIVERSE
COMPOSITION OF EARTH
90 Naturally occurring
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).
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)?
1. Negative charge
2. 1835 electrons weigh 1 amu.
3. Responsible for chemical bonds
1. No net charge
2. Weighs 1 amu
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.
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
What does the 92 mean? What does the 238 mean?
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
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.
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.