1. Ms. Samayoa Birmingham Community Charter High School Chemistry
Simple Ions
Ms. Samayoa
Birmingham Community Charter High School
Chemistry

2. Learning Objective
Students will learn how to predict the type of ion that a given element forms from its position on the periodic table

3. Simple Ions
How much an element reacts depends on its valence electron configuration
Ask students what reactivity property do noble gases have

4. The noble gases show almost no chemical reactivity Why?
Simple Ions
The noble gases show almost no chemical reactivity
Why?
Because they have a FULL valence shell of electrons!
Reactions occur when atoms lose or gain electrons
Because noble gases don’t lose or gain electrons there is no chemical reactivity

5. Simple Ions: The Octet Rule
As we’ve learned before, atoms like to be stable
Feel most stable when electron shells are full
Electron shells become full when they have eight valence electrons
This is called the OCTET RULE, which says that atoms like to have full valence shells of eight electrons
Ask student to state what octet rule means

6. Simple Ions: The Octet Rule
How many valence electrons do noble gases have? 8

7. Check for Understanding
Explain why the noble gases tend not to react using the following vocabulary words: valence electrons and octet rule
Sentence starter:
Noble gases don’t tend to react because….

8. Simple Ions: The Octet Rule
Atomsreactsothattheycanacheivethesameelectron configurationsasthenoblegases
Atoms react so that they can achieve the same electron configurations as the noble gases

9. Write the electron configuration of POTASSIUM.
PRACTICE
Write the electron configuration of POTASSIUM.

10. Simple Ions 1s22s22p63s23p64s1 Example: Potassium (K)
How many valence electrons does potassium have to lose to have an electron configuration of a noble gas? Which noble gas?
Potassium wants to lose ONE valence electron to achieve the same valence electron configuration as ARGON  1s22s22p63s23p6

11. Simple Ions K  K+ + e After giving up one electron…
Potassium still has 19 protons
But only 18 electrons
= +1
Because the numbers are not the same, there is an overall electrical charge = ION
K  K+ + e

12. Ions that have a positive charge are known as CATIONS
Elements lose electrons to form cations

13. Finish this sentence
Since potassium lost an electron, it has a ________ charge and is classified as ___________

14. Write the electron configuration for chlorine
PRACTICE
Write the electron configuration for chlorine

15. PRACTICE Example: Chlorine (Cl) 1s22s22p63s23p5
How many valence electrons does chlorine have to gain to have an electron configuration of a noble gas? Which noble gas?
Chlorine wants to gain ONE valence electron to achieve the same valence electron configuration as Ar  1s22s22p63s23p6

16. Simple Ions After gaining one electron… Chlorine still has 17 protons
But only 18 electrons
= -1
Because the numbers are not the same, there is an overall electrical charge = ION
Cl + e  Cl-

17. Ions that have a negative charge are known as anions
Elements GAIN electrons to form ANIONS

18. Finish this sentence
Since chlorine gained an electron, it has a ________ charge and is classified as ___________.

20. Think About it…
You will be given 2 minutes to find a question to the answer given.
Partner A: The answer is cation. What is the question?
Partner B: The answer is anion. What is the question?

21. Think About It… Now share with your partner:
Partner A: Write down the question that your Partner B came up with in your notes and explain why anion is the answer
Partner B: Write down the question that your Partner A came up with in your notes and explain why cation is the answer

22. Think About It…
Partner A: Give an example of an element that LOSES electrons to form an ion with a POSITIVE CHARGE
Partner B: Give an example of an element that GAINS electrons to form an ion with a NEGATIVE CHARGE

23. Exceptions Many stable ions have noble-gas configurations
However some stable ions do not have noble-gas configurations
Transition metals often form ions WITHOUT complete octets
ALL TRANSITION METALS FORM CATIONS
Notice that mostly transition metals can form several stable ions that have different charges
Example copper
Can give up one electron or can give up two and both are stable even though they do not have noble gas configurations

24. COMMON MISCONCEPTIONS
“An atom and its ion have the same chemical properties.” WRONG!!!!!!!!
e.g. Sodium ion vs Sodium
Explain that sodium is extremely reactive
Chlorine is also reactive
When reacting together very violent
Although made from two dangerous elements, something you can eat because they are cation and anions

25. COMMON MISCONCEPTIONS
When an atom loses/gains electrons to form an ion, it achieves an electron configuration IDENTICAL to a noble gas
That does not mean it becomes a noble gas!
Na vs Ne
Sodium still has ___ protons and Neon has ____ protons