Chemistry- Reactivity and Electrons

7/29/2019 Chemistry- Reactivity and Electrons

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CHEMISTRY: ELECTRONS

AND REACTIVITY


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Click forSodium and Potassium Movie

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1. Compare the reactions of sodium

and potassium in water.

2. Why do you think that they

reacted similarly?
http://teachertube.com/viewVideo.php?video_id=167365&title=Sodium_in_Water__Potassium_in_Water&vpkey=4c7340bdfb&album_id=http://teachertube.com/viewVideo.php?video_id=167365&title=Sodium_in_Water__Potassium_in_Water&vpkey=4c7340bdfb&album_id=


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The Periodic Table

Period

Group or

family

Groups or families are vertical columns in the periodic table

The zig- zag line separates metals from

non-metals

With the discovery ofisotopes by Mosley in 1909, the Periodic Table was

reorganized by increasing atomic number (number of protons).

This is modern Periodic Table we use today!


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11

Na

22.998

Atomic Number =

# protons (+)

Atomic Mass = Mass #

(rounded)= protons + neutrons

Symbol

P+N

Sodium contains how many of the following?

Atomic # Mass # Protons Neutrons Electrons

EnergyLevel filling

28

8 or 1832

BOHR MODEL OF

ATOM:

Level 1

Level 2


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How many protons and electrons are found in an atom ofChlorine?

How many neutrons are found in an atom of Sodium (Na) that has

a mass number of 23 amu?

What happens to an atom when you add anotherproton?

How can you change the mass number of an atom of sodium?

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COMPLETE THE FOLLOWING TABLE FOR

ELEMENTS 1-21

ElementSymbol

Atomic #

AtomicMass

Mass#

#Proton

s

#Neutron

s

#Electron

s

BohrModel

LI 3 6.941 7 3 4 3

3

4

2e-

1e-

1. How many outer shell electrons are present in all group 1A Elements?

In Group 2A? In Group 3A? In Group 4A? 5A? 6A? 7A? 8A?


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These are the electrons found in the last level of an atom.

They are the MOST important electrons in determining thereactivity of an atom.

Elements with the same number ofvalence electrons will reactsimilarly.

As a rule elements in the same group have the same number of

valence electrons.

For example: Hydrogen, Lithium, Sodium etc all have 1 valenceelectron.

GROUPS 1A 8A GIVE THE # OF VALENCE ELECTRONS

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Lithium is #3 in the periodic table. So it has THREEelectrons.

As we had stated before two electrons are in first level,leaving ONE electron in level 2.

So Lithium has ONE valence electron.

8


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How many electrons are there in an atom of Sulfur (S)?

How many valence electrons are found in an atom of Sulfur?

Name an element that would have similarchemical properties toSulfur.

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Click here for: Graphing Lab #2

Click here: Post Lab Clip
http://localhost/var/www/apps/conversion/tmp/scratch_5/Appendix/Graph%20activity%202.dochttp://dwb4.unl.edu/ChemAnime/ATRADIID/ATRADIID.htmlhttp://dwb4.unl.edu/ChemAnime/ATRADIID/ATRADIID.htmlhttp://localhost/var/www/apps/conversion/tmp/scratch_5/Appendix/Graph%20activity%202.doc


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Elements react in order to have 8 valence

electrons in their last energy level.

This is called the Octet Rule

In order to complete follow the octet rule,

elements either gain or lose electrons and for

IONS.

Cations = lose e- form positive ionsAnions = gain electrons and form negative ions

Build and Atom Simulation

WHY DO ELEMENTS REACT AND FORM

COMPOUNDS?
http://phet.colorado.edu/en/simulation/build-an-atomhttp://phet.colorado.edu/en/simulation/build-an-atom


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CA +2 N-3

Metals lose theirvalence electrons to form cations Cations = positive. (Cats whiskers)

Click here for: Cation clip

Nonmetals will gain enough electrons to form anions. They willtake as many electrons they need to get 8 valence electrons.

Anions = negative (An means to negate)

Click here for:Anion clip

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http://localhost/var/www/apps/conversion/tmp/scratch_5/Appendix/04_01c1.MOVhttp://localhost/var/www/apps/conversion/tmp/scratch_5/Appendix/04_01d1.MOVhttp://localhost/var/www/apps/conversion/tmp/scratch_5/Appendix/04_01d1.MOVhttp://localhost/var/www/apps/conversion/tmp/scratch_5/Appendix/04_01c1.MOVhttp://localhost/var/www/apps/conversion/tmp/scratch_5/Appendix/04_01c1.MOVhttp://localhost/var/www/apps/conversion/tmp/scratch_5/Appendix/04_01c1.MOV


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1. Mr. Lopezs science class is playing an educational game to study the

periodictable. He gives Trahn a card with some clues to help him identify aparticular group on the periodic table. Below is Trahns card.

1313

FCAT Science Sample Test Book 2007

Trahns card describes which group on the periodic table?

F. Group 1

G. Group 2

H. Group 16

I. Group 18

Which chemical group

1. Reacts with water to form basic solutions2. Readily combines in nature to form other compounds

3. Loses 2 outer energy level electrons to form +2 ions


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Julio is given an unknown element to study. After carefully analyzing

his element he arrives at the following conclusions.

His element has a very low density and when it reacts with otherelements it gains 3 electrons to form an anion with a -3 charge.

In which of the following groupscould we find Julios element?

A) Group 3

B) Group 5

C) Group 13

D) Group 15

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3. Suppose a scientist makes an unexpected discovery about thepossible existence of a new element. The finding does not fit wellwith the initial hypothesis. The scientist is a member of a team ofresearchers. If the team behaves according to the best principlesof scientific inquiry, which of the following would NOT occur?

A) rejection of the finding as being impossible.B) willingness to repeat the studies that led to the finding for

confirmation.

C) urging the scientist to communicate findings to other

researchers.

D) insistence on reviewing all data carefully and systematicallyfor any errors.

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Chemistry- Reactivity and Electrons