Do Now 1/7/10Explain IN COMPLETE SENTENCES why

atoms are neutral in charge.

HINT: think about the charges and numbers of the subatomic particles

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Do Now Discussion

• Atoms are neutral because they have equal numbers of protons and electrons.

• Protons are positively charged and electrons are negatively charged

• When equal in number, the charges cancel each other out.

Review: What is an ion?

A single atom or groups of atoms with either a positive or negative charge.

Cation: positively charged ionRemember: Cats purrrrr.

Anion: negatively charged ionThink: If you are “anti” something, you are

against it, or have a negative opinion of it.

How do Ions form?Ions form when atoms lose or gain valence

electrons.

Lose electrons = Make a CATION

Gain electrons = Make an ANION

Na Na+

Atoms want 8 e- in their valence shell so it is full. This will give them the configuration of a noble gas

Atoms lose, gain, or share e- in order to get 8 e- in their valence shell

Na Cl+ Na+ Cl+-

Cation,Like Ne

Anion,Like Ar

Octet Rule “octo” means 8

Trends in Ion Formation

Groups 1, 2, 13 & sometimes 14 give their valence electrons away (lose)

12 1314 Li Li+

Mg Mg2+

B B3+

Trends in Ion Formation

Groups 15, 16, 17 take electrons (gain)

151617 P P3-

O O2-

F F-

Trends in Ion Formation

Group 18 doesn’t form ions (noble gases)They already have the lucky 8 electrons!

18

Example 1What would be the ion for Calcium (Ca)?

Group

Gain/Lose electrons

Charge

2

Lose

2+

IonCa2+

Example 2What would be the ion for Boron (B)?

Group

Gain/Lose electrons

Charge

13

Lose

3+

IonB3+

Example 3What would be the ion for Phosphorus (P)?

Group

Gain/Lose electrons

Charge

15

Gain

3-

IonP3-

Do Now for 1/8 (15 min)

1. Read the article that you should have grabbed from the table up front.

2. Answer questions 1-4 on your “Do Now” sheet.

Dictionaries are on the book cart.

3. When you are done, order all of your “Do Now” sheets from 11/17/09 until today, STAPLE them NEATLY, and put them in the HW bin.

If you do not have them with you today, turn all of them in (including today’s) on Monday.

4. Return the article NEATLY to the stack on the table.

Review from yesterday

What would be the ion for Sulfur (S)?

Group

Gain/Lose electrons

Charge

16

Gain

2-

IonS2-

One moreWhat would be the ion for Beryllium (Be)?

Group

Gain/Lose electrons

Charge

2

Lose

2+

IonBe2+

PracticeWhat group is Sodium in?What is the atomic #?How many:

Protons = ______ Electrons = ______

What is the e- configuration for Na?

How many valence e- does Na have?

Group 1

1 from the 3s block = 1 valence e-

1s22s22p63s1

1111

11

Na11 protons11 neutrons

Na needs to loose 1 e- to have a full outer shell!

Cation

PracticeWhat group is Fluorine in?What is the atomic #?How many:

Protons = ______ Electrons = ______

What is the e- configuration for F?

How many valence e- does F have?

Group 17

2 from the 2s block + 5 from the 2p block = 7 valence e-

1s22s22p5

99

9

F9 protons9 neutrons

F needs 1 more e- to fill it’s outer shell!

Anion

So what happens?

F9 protons9 neutrons

Na11 protons11 neutrons

Na looses its single e- in the 3rd energy level, donating it to F

Na+ no longer has e- in the 3rd energy level, but does have a full 2nd energy level w/ 8 e-

Has become a Na+ ion.

F now has a full 2nd energy level with a full 8 e-, and has become the F- ion.

1. What do you notice about the e- shell diagrams after the e- has been given to F?

2. What element has this e- configuration normally?

+-

Exit Slip – Respond on your “Do Now” sheet from today. Then turn all of your “Do Nows”

in.

“Do Now” 1/11/10Respond using complete sentences!!1. Identify the number of protons in K

and then identify the number of electrons in K.

The number of protons in K is 19. The number of electrons in K is 19.

2. Identify the number of protons in K+ and the number of electrons in K+.

The number of protons in K+ is 19. The number of electrons in K+ is 18.

3. Is K+ an anion or cation?

Periodic Trends (Ch. 6)

Trends are: Predictable ways in which something changes Things that are commonly seen (think fashion

trends)

Atomic Radius Trend in the size of an atom

Ionic Radius Trend in the size of ions of an atom when they have

formed

Ionization Energy Trends in the amount of energy needed to remove a

single e- from an atom

Get ready for Cornell notes!!!

Atomic RadiusAn atom’s size is determined by the space occupied

by its e- cloud Remember: The e- cloud is the area around the nucleus where the

orbitals containing the e- are.

Size is measured by determining the size of the radius.

Turn to p. 187, look at graphic

Radius of: Metals = ½ the distance

between nucleus of 2 atoms next to each other in crystal form

Nonmetals = Distance between nuclei of 2 bonded atoms of the same element.

Turn to p.188 – Atomic RadiusGenerally decreases

Gen

eral

ly in

crea

ses When drawing arrows to

show trends, always start from the upper right

corner!Period 1, Group 1

What trend(s) do you notice as you move from left to right across the periods?

Do you have more or less e- as you move from left to right?

The size _________ because:

Trends in periods

The atomic radius gets smaller as you move from left to right

• Elements in the same period have the same highest (principal) energy level.

• e- AND protons are added (atomic # increases) • Nucleus has more power to pull e- in principal

energy level closer to nucleus (= smaller radius)

decreases

Less e-

Trends in groupsWhat trend(s) do you notice as you move

from top to bottom?

Do you have more or less e- as you move from top to bottom?

The atomic radius gets _________ because:

The atomic radius gets larger as you move from top to bottom

More

larger

Each atom has the same # of e- in their valence shell, but the highest (principal) energy level has increased by 1 each time you move down. (You would need to draw an additional shell around the nucleus.)

Examples Using only your notes and a periodic table,

which would have a bigger radius?

He / Ar

K / Ar

Fe / Br

Ar

K

Fe

Mg / S Mg

Ionic RadiusSize of radius of an atom after it has gained or

lost e- to become stable Remember: Stability is achieved by having a full valence shell.

Size is measured by determining the size of the radius, same as for atomic radius.

Turn to p. 190, look at graphicThe ionic radius becomes:

Smaller = When e- are lost Larger = When e- are gained

e- gainede- lost

Ionic Radius, p. 190

Write down your thoughts in your notes:1. What is happening between Groups 14 and

15 that accounts for the sudden increase in the size of the ionic radius?

Ionic Radius, p. 190

According to the image, Group 14 elements donate their 4 valence e-

Loosing e- = smaller radius

Group 15 is gaining e- (only needs 3 to fill shell)

Gaining e- = larger radius

Ionization EnergyEnergy required to remove an e- from an

atom Only looking at energy required to remove valence e-, so those in

the outermost shell or highest (principal) energy level.

Think about how ions are formed (which groups give up e- and which ones take e-) and write down your thoughts to the following ?’s:

1. As you move from left to right, would you expect it to be easier or harder to remove valence e-? Why??

2. As you move down a group, would you expect it to be easier or harder to remove valence e-? Why??

Graph showing Ionization Energy

Look at the elements that are represented by the circles – Why do you think the amount of energy needed may have decreased for these? Think about what happens to the e- configuration …

New energy sub-level (from s

block to p block, etc.)

Ionization Energy cont.

From left to right = Increase in the amount of energy (more needed) As # of valence e- increases, more energy is

needed More protons to pull e- towards nucleus

From top to bottom = Slight decrease in the amount of energy needed (less needed) As atomic radius increases due to additional

energy levels (more shells), e- are farther from the nucleus and it is harder for protons to hold on to them.

Trend in Ionization Energy