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