Review Electrons are the negatively charged part of the atom Electrons are found in orbitals around the nucleus We write the electron configuration of the element to see the different orbitals ID: 436901
Download Presentation The PPT/PDF document "Valence Electrons Day 1" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Valence Electrons Day 1Slide2
Review
Electrons are the negatively charged part of the atom
Electrons are found in
orbitals
around the nucleus
We write the electron configuration of the element to see the different
orbitals
the electrons are located inSlide3
Review
Write the electron configuration for Lithium…
Write the electron configuration for Fluorine…Slide4
Valence electrons
The electrons in the last energy level of the element are the VALENCE electrons
The last energy level is the part of the configuration that has the largest number in front of it
Lithium = 1s
2
2s
1
Fluorine = 1s
2
2s
2
2p
5
Slide5
Valence electrons
An element can have anywhere from 1-8 valence electrons
The number of valence electrons determines how REACTIVE the element is
8 = totally
unreactive
1 and 7 = extremely reactive
2 and 6 = pretty reactive
3-5 = only
kinda
reactiveSlide6
How to find valence electrons?
Pull out your periodic table!
You can find the valence electron of the element by seeing what group it is in….
Where are the groups on the periodic table?Slide7
You should already have groups 1-18 listed on your periodic table
Group 1 = 1 Valence Electron
Group 2 = 2 Valence Electrons
Group 13 = 3 Valence Electrons
Group 14 = 4 Valence Electrons
Group 15 = 5 Valence Electrons
Group 16 = 6 Valence Electrons
Group 17 = 7 Valence Electrons
Group 18 = 8 Valence ElectronsSlide8
What about groups 3-12?
The transition metals in groups 3-12 have their own set of rules
Don’t worry about them for nowSlide9
In - Class Practice: Due at end of hour!
Write down the following elements on a sheet of paper… next to them find out how many valence electrons they have?
1. Neon 2. Sodium 3. Aluminum
4. Calcium 5. Sulfur 6. Iodine 7. Carbon
8. Lead 9. Phosphorus 10. KryptonSlide10
Valence Electrons Day 2Slide11
Review
How many valence electrons does Arsenic have?
How many valence electrons does Potassium have?Slide12
Valence Electrons
To find the number of valence electrons for the elements in groups 1,2 and 13-18 you look at your periodic table
Transition metals (groups 3-12) have their own rulesSlide13
Transition Metals
To find the number of valence electrons for a transition metal you have to write the shorthand electron configuration for that metal
For example… Iron’s shorthand electron configuration is [
Ar
] 4s
2
3d
6Slide14
Transition Metals
Just like the regular valence electrons, we look at the highest energy level
Iron’s shorthand electron configuration is [
Ar
]
4s
2
3d
6
4s
2
= highest energy level
Iron has 2 valence electronsSlide15
Transition Metals
All transition metals will have a shorthand configuration that gives you 2 valence electrons
However, Transition Metals can act like they have anywhere from 1-4 electronsSlide16
Homework
“Valence Electrons” side of worksheet
For each question you should
Write the shorthand electron configuration
Write how many valence electrons each element hasSlide17
Valence Electrons Day 3Slide18
Review
By now we know that an element can have anywhere from 1-8 valence electrons
We can find the number of valence electrons the element has by looking at the periodic table or by its electron configurationSlide19
Valence Electron Review
For Groups 1,2, 13-18 the number of valence electrons depends on group it is in
Exception! Helium is a noble gas and is full, but because of its electron configuration it has 2 valence electrons, not 8
Transition metals in groups 3-12 all have 2 valence electrons, even though they don’t always act that waySlide20
Lewis Structures
We can draw Lewis Structures to represent the valence electrons of an element
To draw
a Lewis Structure
Put the element symbol in the middle
Determine how many valence electrons it has
Draw a dot for each electron around the symbolSlide21
Important Rules
As you are putting the dots around the symbol you start by putting one dot on each side of the symbol
No side should ever have more than 2 dots
Example: Electron dot diagram for Carbon
:
C:
C Slide22
Practice
Draw the electron dot diagram
Put the element symbol in the middle
Determine how many valence electrons it has
Draw a dot for each electron around the symbol
Na
Cl
Mg
ArSlide23
Homework
“Lewis Dot Diagrams” side of worksheet
Remember, Helium is an exception to the noble gases, it only has 2 valence electrons!