Miss FoggFall 2015
ELECTRONSVALENCE ELECTRONS
BORH DIAGRAMS
2-8-8 Rule Electrons orbit the nucleus in energy levels within the electron cloud
The 1st energy level holds 2 electrons
The 2nd and 3rd energy levels holds 8 electrons
1
2
1 2
3
4
56
7
8
1 2
3
4
56
7
8
Valence Electrons
Valence Electron
VALENCE ELECTRONS
Valence electrons: electrons in the last shell or energy level of an atom.
1
2
1 2
3
4
56
7
8
1 2
3
4
56
Last energy level: Level 3
So count the electrons in the last energy level
6 Valence Electrons!
VALENCE ELECTRONS
1
2
1 2
3
4
56
7
8
1 2
3
How many valence electrons are in this atom?
3Valence Electrons
VALENCE ELECTRONS
1
2
1 2
3
4
5
How many valence electrons are in this atom?
5Valence Electrons
VALENCE ELECTRONS
1
How many valence electrons are in this atom?
1Valence Electrons
VALENCE ELECTRONS
1
2
1 2
How many valence electrons are in this atom?
2Valence Electrons
Happy Atoms
VALENCE ELECTRONS
“Happy" atoms are stable atoms
Atoms are stable when their outermost energy levels (shells) are full
1
2
1 2
3
4
56
7
8
1 2
3
4
56
7
8
1
2
1 2
3
4
56
7
8
1
2
Stable
Stable
Stable
1
2
1 2
3
4
56
7
8
Is this atom stable?
YES!
VALENCE ELECTRONS
Is this atom stable?
NO!
1
2
1 2
3
4
56
7
8
1 2
3
4
56
7
Valence Electrons
SadAtoms
VALENCE ELECTRONS
Sad atoms are not stable When an atom's outermost shell
is not complete/full it is not stable.
1
2
1 2
3
4
56
7
8
Is this atom unstable?
NO!
VALENCE ELECTRONS
Is this atom unstable?
YES!
1
2
1 2
3
4
56
7
8
1 2
3
4
56
7
Valence Electrons
SadAtoms
VALENCE ELECTRONS
Atoms become stable by bonding (joining) with other elements. Bonded atoms are called molecules. A covalent bond is one where atoms share
electrons. An ionic bond is one where electrons are
either given or taken, not shared. A metallic bond is when metal ions share a
pool of electrons
We can draw Bohr Models to summarize all the information we know about an element
BOHR DIAGRAMS
Nucleus (with # protons and # neutrons)
2 electrons found on first shell
8 electrons found on second shell
1 valence electron
Sodium (Na)
1. Draw the nucleus as a circle
2. Put the # of protons & # of neutrons inside the nucleus
3. Draw the appropriate # of electron shells around the nucleus
4. Draw the electrons counter clockwise from the inner shell to the outer shells, following the electron orbital rules
HOW TO DRAW A BORH DIAGRAM
6 p+6 n
6 - Carbon
1. Draw the nucleus as a circle
2. Put the # of protons & # of neutrons inside the nucleus
3. Draw the appropriate # of electron shells around the nucleus
4. Draw the electrons counter clockwise from the inner shell to the outer shells, following the electron orbital rules
HOW TO DRAW A BORH DIAGRAM
7 p+7 n
7 - Nitrogen
1. Draw the nucleus as a circle
2. Put the # of protons & # of neutrons inside the nucleus
3. Draw the appropriate # of electron shells around the nucleus
4. Draw the electrons counter clockwise from the inner shell to the outer shells, following the electron orbital rules
HOW TO DRAW A BORH DIAGRAM
13 p+14 n
13 - Aluminum