Chemistry ReviewYou need to remember some basic things

The Atom

•Smallest possible unit that maintains properties of the element

•Made of:▫Protons – positively charged particles▫Neutrons- neutral particles

Together form the atomic nucleus▫Electrons- negatively charged particles

•Each element has a unique number of protons (atomic number)

Electron Orbitals/Shells•Electrons are found

in characteristic areas around the nucleus, called an orbital▫Each one represents

a different energy level

•Simplifying things, orbitals are grouped into “shells”

Electron Shells

•The innermost shell is filled first

•The outermost shell is called the valence shell

Electron Shells Con.

•The first shell has only 1 orbital, so it can hold only 2 electrons

The 2nd/3rd Shell

•Consists of 4 orbitals, so each shell can hold 8 electrons

Represents 1 Orbital. Each orbital gets 1 electron before any orbital in the shell gets a 2nd

Draw on your Whiteboard

•A neutral boron atom (for the nucleus you can just write B)

•A neutral fluorine atom

Using the Periodic Table• Ignore the D block (the metals)• The row tells you the # of shells the atom should have• The column tells you the # of valence electrons a neutral atom

should have in its valence shell

Please add these to your table!

Practice using the “short cuts” Draw

•A neutral magnesium atom

•A neutral phosphorus atom

Ions: Atomic Charge

•Charged atoms

•+ ions = more protons than electrons

•- ions = more electrons than protons

Draw the ions on your Whiteboard

•Na+

•Si2-

Filling Valence Shells

•Generally chemical reactions occur that fill valence electron shells

•Either by gaining/losing electrons OR

•By sharing electrons with other atoms

Lewis Structures

•Atoms almost always will end up with 8 electrons in their valence shell (may be lone pairs or shared electrons)**

•So an atom that normally has 6 valence electrons needs to get 2 more from bonding

(only showing the valence electrons)

The column can be used to figure out how many bonds an atom will normally form

4 3 2 1 0