Notes :The Bohr Model

&Happy Atoms/Ions

What atom (element) do you think this is? How can you tell?

Bohr Model Diagrams• Atom is always neutral (=numbers of e- and

+)• Electrons in an atom are arranged in

energy levels (or shells) around the nucleus.

• Electrons in the 3rd energy level have more energy than electrons in the first energy level.

• Maximum # of electrons in the first energy level (shell) is 2. Max # of electrons in the second energy level (shell) is 8.

• The outermost energy level (shell) can never have more than 8 electrons in it (2,8,8,...). These outer electrons are called valence electrons.

Steps to drawing a Bohr model

• First step: Determine the number of protons, neutrons and electrons in each element.

• Second step: Represent the nucleus as a small circle and indicate the number of protons and neutrons.

• Third step: Making larger circles, arrange the electrons around the nucleus.

What atom (element) do you think this is?

=

=

Proton

Neutron

Electronegativity

Happy Atoms• Atoms are “happy” (most stable) when they

have a full shell (2,8,8,…) of electrons.• To become happy, some atoms (usually metals)

will give up their outermost electrons (valence electrons) to other atoms.

• This leaves them with fewer electrons than protons so that overall they have a 1+, 2+ or even 3+ charge. We call these atoms ions.

• Non-metals (right side of periodic table) will take electrons from metals to fill their outer shell.

• This means they have more electrons than protons so that they have a 1-, 2-, or 3- charge. These atoms are also ions.

The Making of an Ion

Na1+ Cl1-

I’m happy now. How about you?

Yep.