chemistry review you need to remember some basic things
TRANSCRIPT
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
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
Ions: Atomic Charge
•Charged atoms
•+ ions = more protons than electrons
•- ions = more electrons than protons
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)