Bell Ringer

• 1. What is ionization energy?• 2. Which atom has the higher ionization

energy?– Li or Cl?– Na or Br?

• 3. Identify the three subatomic particles and name the type of charge for each.

• 4. What is the electron configuration of sodium?

Outline• Bell Ringer• Objectives

– SWBAT explain why atoms form ions.– SWBAT identify the atoms most likely to form positive ions and the atoms

most likely to form negative ions.– SWBAT indicate the most likely number of electrons the atom will gain or lose

given the symbol of a main group element.– SWBAT predict the charge on ions from the ionization energies and electron

configuration of the atom. • Essential Vocabulary

– Anion– Cation

• Essential Question– Why does sodium react readily with oxygen and explosively with water?

• Work Period– Partner Practice Problems

• Closure – Practice Test Question

• Anything that looks like this must be in your notes

• Anything else is bonus material

Na + H2O

• Why do you think sodium reacts violently with water?

– Think about sodium’s electron configuration

• You might think that the most stable form for an element is that of a neutral atom

• However, there are approximately 190,000,000,000,000,000 kilotons of sodium on earth, yet almost none of that is in the form of sodium atoms– What form is it in then?

• If sodium ions and not sodium atoms can be readily found in nature, it is due to the fact that ions are chemically more stable than atoms– Chemically stable = less likely to undergo

chemical change

• One of the major tendencies that causes change to occur in chemistry is the tendency for matter to alter its condition in order to achieve lower potential energy

• Rubber band example

• The house of cards will remain balanced, provided no one wiggles the table

• But, if someone wiggles the table, the structure will fall to a lower potential energy

• Much like the cards, atoms and molecules are in constant random motion

• This motion causes collisions between the particles– These collisions initiate

the change to lower potential energy

Ion Formation

• An atom becomes an ion when it gains or loses electrons

• Cations are positively charged ions that form when an atom LOSES electrons

• Anions are negatively charged ions that form when an atom GAINS electrons

Ion Formation

• When fluorine takes on an extra electron, it releases energy and moves toward lower potential energy

Metals have low ionization energies and therefore lose electrons readily and tend not to gain electrons

Nonmetals have high ionization energies and therefore do not lose electrons but tend to gain electrons

• Atoms bump into each other and the atom with low IE (metal or nonmetal?) will lose an electron to the other (metal or nonmetal?)

Recall

• Ionization energy – energy required to remove an electron from an atom

– If we’re removing electrons, are we creating positive or negative ions?

Ionization EnergiesWhat charge?

Ionization EnergiesWhat charge?

Ionization Energies

What about aluminum?

What charge?

Partner Practice

1. In general, how does the ionization energy of a metal compare to the ionization energy of a nonmetal?

2. Will an iron atom form a positive or negative ion? Why?

3. Will a bromine atom form a positive or negative ion? Why?

Partner Practice

4. Which is larger, a fluorine atom or a fluoride ion?

5. How is the number of valence electrons of a metal atom related to the charge on the ion the metal will form?

6. How is the number of valence electrons of a nonmetal related to the charge on the ion the nonmetal will form?

Partner Practice

7. If carbon were to behave like a metal and give up electrons, how many electrons would it give up?

8. How many electrons are in a typical sodium ion?

9. Explain why chlorine is a small atom that tends to take on an extra electron, but argon is an even smaller atom that does not tend to take on electrons.

Partner Practice

10. If an atom had the following successive ionization energies, to which family would it belong? Why did you choose this family?– 1st ionization energy = 75 kJ/mol– 2nd ionization energy = 125 kJ/mol– 3rd ionization energy = 1225 kJ/mol– 4th ionization energy = 1750 kJ/mol

Test Question