OBJECTIVES:
1. Be able to describe an element by the way its electrons are orbiting the nucleus.
How many energy levels?
Which energy sublevels?
How many electrons are represented in each?
2. Create Lewis Dot structures to represent valence electrons in atoms.
1. Be able to describe an element by the way its electrons are orbiting the nucleus.
How many energy levels?
Which energy sublevels?
How many electrons are represented in each?
2. Create Lewis Dot structures to represent valence electrons in atoms.
STEP 2: This is a short-cut to Bohr diagrams for understanding electrons. Valence electrons (the outermost e-) are the most important for determining basic chemical reactions.
1. Write the symbol first.
2. Look it up on the periodic table
3. Use the number at the top of the chemical family.
4. Put this many dots around the symbol.
5. Dots should be "single" first, then double or partnered.
1. Write the symbol first.
2. Look it up on the periodic table
3. Use the number at the top of the chemical family.
4. Put this many dots around the symbol.
5. Dots should be "single" first, then double or partnered.
STEP 3: Electron Configurations
-These are a lot like knowing which line you are on when reading poetry or plays or even the Bible, except you are reading the periodic table instead of a text.
1. Start by identifying where the element of interest is, for example Titanium is element 22.
2. Read from the TOP LEFT OF THE PERIODIC TABLE on down to your element just like a book and give:
a. The period you are passing (1-2-3-4)
b. The orbital subshell (block) you are passing (s-p-d-f)
c. How many elements you pass along the way (each one adds an electron)
*Important exception: The D subshell adds to the 3rd energy level even though it begins in the 4th period. Look at the Bohr Diagrams, the 3rd energy level holds 18 electrons. This is where the other 10 come from.
Example: Give the electron configuration for Titanium: 1s2 2s2 2p6 3s2 3p6 4s2 3d2
This says that for titanium the first energy level has 2 electrons in the s orbital
its second energy level has both s & p orbitals full (2+6)
its third energy level has s & p full (2+6)
its fourth energy level has s full (2)
its LAST ADDED ELECTRONS are in the D orbital and THERE ARE 2
SHORTCUT: Use the noble gas configuration of the period before to denote FULL energy levels
Example: Titanium becomes [Ar]4s2 3d2
-These are a lot like knowing which line you are on when reading poetry or plays or even the Bible, except you are reading the periodic table instead of a text.
1. Start by identifying where the element of interest is, for example Titanium is element 22.
2. Read from the TOP LEFT OF THE PERIODIC TABLE on down to your element just like a book and give:
a. The period you are passing (1-2-3-4)
b. The orbital subshell (block) you are passing (s-p-d-f)
c. How many elements you pass along the way (each one adds an electron)
*Important exception: The D subshell adds to the 3rd energy level even though it begins in the 4th period. Look at the Bohr Diagrams, the 3rd energy level holds 18 electrons. This is where the other 10 come from.
Example: Give the electron configuration for Titanium: 1s2 2s2 2p6 3s2 3p6 4s2 3d2
This says that for titanium the first energy level has 2 electrons in the s orbital
its second energy level has both s & p orbitals full (2+6)
its third energy level has s & p full (2+6)
its fourth energy level has s full (2)
its LAST ADDED ELECTRONS are in the D orbital and THERE ARE 2
SHORTCUT: Use the noble gas configuration of the period before to denote FULL energy levels
Example: Titanium becomes [Ar]4s2 3d2