You need to remember some basic things Chemistry Review You 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
The first shell has only 1 orbital, so it can hold only 2 electrons Electron Shells Con. The first shell has only 1 orbital, so it can hold only 2 electrons
Represents 1 Orbital. Each orbital gets 1 electron before any orbital in the shell gets a 2nd The 2nd/3rd Shell Consists of 4 orbitals, so each shell can hold 8 electrons
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