Catalyst – September 4 + 24, 2010

1. What is an ion?2. What are the 2 types of

ions?3. Fill in the blanks:

___________ electrons are those that interact to form chemical ________s.

Today’s Agenda

CatalystReview of FridayOctet Rule and Stable IonsProperties of Ionic Compounds (tom)

Exit Question, Tests, and Progress Reports

Today’s Objectives

SWBAT use the octet rule to predict the stable ion an atom will form in a chemical bond.

SWBAT describe the properties of ionic compounds. (tomorrow)

Review: What is a compound?A compound results from interaction between valence electrons of different atoms.

Review: Lewis Dot Structures

Lewis Dot Structures only show the number of valence electrons in an atom.

Valence electrons are the only electrons involved in bonding

Valence electrons are the most important electrons

Review: Lewis Dot Sructures

What do the Lewis

Dot Structures

have in common?!?

!?

Review: Ions

An ion is an element that has gained or lost an electron. Cation = positive ion (+)Anion = negative ion (-)

+

-

Formation of Negative Ions (ANIONS) Imagine that electrons are

pieces of poop Is poop is flying into your

yard (an atom’s energy levels) a positive or negative thing?

So…if poop lands in your yard, are you more positive or more negative?

So…NEGATIVE ions are formed when an atom GAINS one or more electrons!

-

Formation of Positive Ions (CATIONS) Imagine that electrons are

pieces of poop Is poop in your yard (an

atom’s energy levels) a positive or negative thing?

So…if you get rid of the poop in your yard, are you more positive or more negative?

+

So…POSITIVE ions are formed when an atom LOSES one or more electrons!

Practice Questions

1. If an atom gains an electron it will have a ___________ charge.

2. If an atom loses an electron it will have a ___________ charge.

3. If chlorine gains 3 electrons it will have a _______ charge.

NEGATIVE

POSITIVE

3-

Ions!

Cl loses 4 Electrons

What is the ion formed?

Ions!

Cobalt gains2 electrons

What is the ion formed?

Ions!

Si3- What happened…

Gain or lose?How many?

Ions

Si3- Silicon gained 3

electronsHow many total

electrons does Si have now?

Practice Problems – Write all down! Write down the ion that will

form for the following: 1. Sr gains 5 electrons 2. Phosphorous loses 1 electron

Then, determine how many TOTAL electrons each ion will have after gaining or losing

Practice Problems – Write all down!

How many TOTAL electrons do the following ions have?

1. Cl2+

2. Li2-

3. Xe3+

4. O1-

5. Zn5-

Notes: Octet Rule

What is different about the valence shells of the elements on the Left and those on the Right?

The noble gases have full valence shells, the other atoms do not…

Key Point #1: The octet rule says that atoms are most stable when they have 8 valence electrons.

1.Atoms can gain or lose electrons to become stable (happy)

2.Atoms with 4 or more valence electrons will GAIN electrons to become stable (happy)

3.Atoms with 3 or less valence electrons will LOSE electrons to be stable (happy)

Octet Rule

Octet Rule - Examples

How many electrons will the following atoms gain or lose to become stable (happy)? How many TOTAL electrons will the atom then have? What is the STABLE ION?

1. F2. O3. N4. H

Try the following on your own How many electrons will the

following atoms gain or lose to become stable (happy)? How many TOTAL electrons will the atom then have? What is the STABLE ION?

1. P2. Kr3. Ca4. I5. K

Classwork

Complete Half-Sheet and leave in group

folder.Then, start working

on HW Worksheet 6.3

Exit Question

1. Anion = _______ charge, Cation = _______ charge

2. What is the STABLE ION that will form for Lithium?

3. Draw the LDS for the following elements: Sulfur Magnesium

HOMEWORK: Worksheet 6.3 AND Unit 2 RESUME!