Note Taking Guide: Radioactive Decay



Name: Date: Period:

Note Taking Guide: Electron Configuration Shorthand Notation & Valence Electrons

Valence Electrons

• Valence electrons are the electron’s located in the ___________________________ energy level or orbit

• These are the electrons that determine the___________________________ properties of an element

• And these are the electrons involved in ___________________________and _________________

• ___________________________ = electrons in _______________ the subshells with the highest principal energy shell (outermost shell)

• _______________________________ = in lower energy shells

• Atoms will try to either _________________ or _________________ electrons in order to get to a full or empty outer most shell

Short hand Notation: Noble gas notation

• A way of abbreviating long electron configurations

• Since we are only concerned about the outermost or valence electrons, we can skip to the closest _________________ and then finish the configuration

• The noble gases have _____________________ valence electrons

• except for He, which has only 2 electrons

• Noble gases are especially _________________; He and Ne are practically inert

• Reason noble gases are unreactive is that the electron configuration of the noble gases is especially _________________

It’s the Showcase Showdown!

• Step 1: Find the closest _________________ to the atom (or ion), WITHOUT GOING OVER the number of electrons in the atom (or ion). Write the noble gas in brackets [ ].

• Step 2: Find where to resume by finding the next ____________________________.

• Step 3: Resume the configuration until it’s finished.

• Step 4: Check by counting the ___________________________of electrons!

Check for understanding:

• Chlorine Longhand is 1s2 2s2 2p6 3s2 3p5

• Write the noble gas notation:

STOP: WRITE THE NOBLE GAS NOTATIONS FOR THE FIRST 20 ELEMENTS

Take aways for writing electron configurations

1. The number of protons equals the ___________________________which equals number of electrons

2. The number of the highest energy levels occupied by electrons equals the ___________________________ of the element.

3. The number of electrons in the highest used energy level (valence level) equals the roman numeral ___________________________.

4. We can break up the periodic table in ___________________________ that correspond to the ending configuration orbitals.

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STOP AND WORK ON COMPLETING WORKSHEET 5-6

What about valence electrons for transition metals?

• The general method for counting valence electrons is generally not useful for the d-block transition metals.

• Therefore, we will focus on s and p block elements.

Check for Understanding: How many valence electrons does each atom have?

| |Number of valence electrons |

|carbon: 1s22s22p2 | |

|magnesium: 1s22s22p63s2 | |

|chlorine: 1s22s22p63s23p5 | |

|gallium: 1s22s22p63s23p64s23d104p1 | |

STOP:

• Write the number of valence electrons for each element in the upper right corner and circle it

• Write the ion most likely to form in the upper right corner

Electron Dot Diagrams

• If you want to see how atoms of one element will react, it is handy to have an easier way to represent the atoms and the electrons in their outer energy levels.

• An electric dot diagram is the symbol for the element surrounded by as many dots as there are valence electrons.

•

• Also known as ___________________________

• Named after G.N. Lewis, an American chemist who developed the method while teaching chemistry class in 1902.

How to write them

• Start by writing one dot on the right of the element symbol, then work your way around ___________________________ adding dots to the bottom, left, and top.

• Add a fifth dot to the top to make a_______________. Continue in this manner until you reach ___________________________to complete the level.

Check for understanding

1. Electrons are now known to swarm around the nucleus of an atom in a configuration known as the _______.

2. What information can you learn from this diagram?

3. The _______ an energy level is from the nucleus, the _______ electrons it can hold.

4.

a. Write the shorthand electron configuration for arsenic (atomic number 33)

b. What block is it in?

c. How many valence electrons does it have?

d. Write the electron dot diagram.

STOP:

Write the electron dot diagrams for the first 20 elements on the periodic table in your packets.

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