 Which
atom
best
represents a
Carbon
atom?
Warm up
Electron Cloud
It’s a small world after all
PLEASE!!!!
Do not sing this terribly annoying song

The electrons swirling around the nucleus
of an atom are called the electron cloud.

This ‘cloud’ contains all the electrons in a
given atom.
Valence
electrons

The electron cloud has different energy levels
that electrons must follow in, called electron
shells.


We will only look at the first three.
The following shells can hold:
1st shell-Up to
2 electrons
2nd shell- up to 8
electrons
3rd shell- up to 18
Electron cloud
Vocab:
Valence electrons:
Electrons on the
outermost shell of
an atom.

So how many
valence electrons
do these atoms
electrons have?

Valence

model- a simple version of a more
complicated system or concept. Models
make something easier to understand.
Models
Just label the shells

The Bohr modelshows ALL the
electrons, protons,
and neutrons in an
atom.
Draw in IAN
The Bohr Model

Scientist use a more simple way to
represent atoms and their valence
electrons than the Bohr model.

An electron dot diagram shows ONLY the
valence electrons of an atom and its
name.

Next, draw the same carbon atom using
the electron dot diagram.
Electron dot diagrams

Draw in IAN the C (Carbon atom) and draw an
arrow to the valence electrons.
Bohr model
Electron Dot model
Bohr model vs. Electron dot
Vocab:
 Rule of eight- all atoms want to have 8
valence electrons to fill up their outer
shell.
 The atom will do whatever it can to make
the rule of 8.

This is a perfect time to introduce
the atoms rule of eight

The atom will give valence electrons away
or steal from other atoms to make their
outer shell have 8 electrons.
Electrons, not money---->
This is a perfect time to introduce
the atoms rule of eight

An atom reacts with another atom based
on its # of valence electrons. (electrons
on the outer shell)

An atom is unstable and wants to react
because of its # of valence electrons.

EVERY chemical reaction happens because
# of valence electrons

This ‘stealing’ and ‘sharing’ is how ALL
reactions happen!!!
Lets do this on the board!!!!!

Another
example.
The electron is
stolen by the Cl
atom and the
Na atom wants
to get rid of it
 Why?

Remember those things called
ions!