Transcript Presentation

Mr. Fleming


Why and how do atoms bond?
What happens when atoms lose or gain an
electron?

Charged atom
◦ Negative- Anion
◦ Positive- Cation

Normal atom
◦ # Protons= # of Electrons
◦ Net Charge=0

Atoms gain or lose electrons in order to have
an outermost orbit of 8 electrons.
 When the valence shell is full, the
atom is stable, less likely to react.
 8 electrons=stable or full valence
shell
 Example: Noble (Inert Gases)
Kr
 Exceptions
to Octet Rule
 Hydrogen only needs 1 more
electron for full valence shell.
 Helium only has 2 electrons, but
still has a full shell.

Charge of Atom= # Protons - # Electrons
Step 1: Find the # protons from the atom’s
atomic number.
Step 2: Subtract the number of electrons from
the number of protons.


What is charge of Aluminum ion that has 13
protons and 10 electrons.
Charge of Ion= 13 protons -10 electrons= +3
Na , 11 e
Na + , 10e


An atom that has lost one or more electrons.
Positively (+) charged.


An atom that has gained one or more
electrons.
Negatively (-) charged.
What do you call atom that has lost an electron
and what is its charge?
Cation, + Charge
How many electrons does the following atom
have: Li+
2 electrons