Extra Credit Opportunities - Science
Complete the following sheets for a maximum of 100 extra credit points.
Name:
Oxidation states
The oxidation number of an element tells you how many electrons an element will either give away or accept. A negative
number means it gains electrons (as electrons have a negative charge, you are adding negatives). A positive number means
that it loses electrons (taking away negative charges creates positive charges). This is very similar to what we had learned
earlier about the creation of ions, although in this case the elements do not necessarily lose or gain the electrons, but might share
the electrons instead.
Negative oxidation numbers
Elements on the right hand side of the periodic table generally have negative oxidation numbers. Remember that the atoms are
most stable with a complete s- and p- energy level, these elements will tend to gain electrons to fill up those orbitals, also known
as an octet, as the s- and p-orbitals can hold a total of eight electrons. Keep in mind, that for the following rules, there will always
be some exceptions and in the future you will come into contact with those exceptions.
Halogens will always need to gain or share an electron, thus they will always have a -1 oxidation number.
The oxygen group generally gains or shares two electrons, so they will have a -2 oxidation number.
The nitrogen group generally gains or shares three electrons, so they will have a -3 oxidation number.
Practice problems
Give the oxidation number of the following elements:
1.
Oxygen
2.
Nitrogen
3.
Fluorine
4.
Sulfur
5.
Chlorine
6.
Iodine
7.
Helium
8.
Astatine
9.
Neon
10. Bromine
11. Phosphorous
12. Tellurium
Positive oxidation numbers
Elements on the left hand side of the periodic table generally have positive oxidation numbers. Remember that the first two
columns of the periodic table are elements that have the valence electrons in the s-orbital. The elements will often lose these
electrons to have filled s- and p-orbitals.
Alkali metals will always lose or share their one electron in the s-orbital. They have a +1 oxidation number.
Example: Potassium has a +1 oxidation number.
Alkaline earth metals will always lose or share their two electrons in the s-orbital. They have a +2 oxidation number.
Example: Calcium has a +2 oxidation number.
Transition metals are those metals to the right of the alkaline earth metals, generally those filling in the d-orbitals. These
metals can have a number of oxidation numbers, so there is not clear rule. The same elements may have several oxidation
numbers, when this is the case, the oxidation number will be shown by roman numerals in parentheses after the name.
Example: Iron (III) has a +3 oxidation number and iron (II) has a +2 oxidation number.
Practice problems
Give the oxidation number of the following elements
1. Lithium
2. Calcium
3. Francium
4. Iron (II)
5. Magnesium
6. Cobalt (III)
7.
8.
9.
10.
11.
12.
Chromium (VI)
Hydrogen
Copper (I)
Beryllium
Aluminum
Potassium
Periodic Table, Elements and Compound Review
Answer Bank for Questions 1-10
nonmetals
in group 1, the first column on the left
period
compound
group18
group
nonmetals
1. The numbers for each group are located
malleable
metals
across the top of the table
______________________________________________________________________________
2. Most reactive metals are found
_____________________________________________________________________________
3. A new gas that would not react with another element would be located in
_____________________________________________________________________________
4. A substance composed of two or more elements chemically combined is called a
_____________________________________________________________________________
5. Elements that are brittle and are poor conductors are
_____________________________________________________________________________
6. Metals can be flatten with a hammer which means they are
_____________________________________________________________________________
7. Elements that are dull and brittle are
_____________________________________________________________________________
8. Elements that are malleable and ductile are
_____________________________________________________________________________
9. Elements in the same horizontal row belong to the same
_____________________________________________________________________________
10. Elements in the same vertical column are belong to the same
_____________________________________________________________________________
Answer Banks for Questions 11-20
to the right of the zigzag line
are poor conductors of electricity
atomic number
element
a zigzag line
liquid at room temperature
its properties
11. Metals are separated by nonmetals on the periodic table by
metal
groups
metalloids
______________________________________________________________________________
12. Most metals are NOT
______________________________________________________________________________
13. The nonmetals are located
_____________________________________________________________________________
14. A physical property of nonmetals is that they
______________________________________________________________________________
15. The semiconductors are located in the
______________________________________________________________________________
16. Columns on the periodic table are called
______________________________________________________________________________
17. A substance that cannot be broken down into any other substance by chemical or physical means is called an
______________________________________________________________________________
18. If an unknown element was shiny and bent easily it would probably be a
______________________________________________________________________________
19. The periodic table is organized by
______________________________________________________________________________
20. From an element’s position in the periodic table, you can predict
______________________________________________________________________________
Answer Bank for questions 21-28
two
the chemicals it reacts with
the left side
three
potassium, carbon, and oxygen
6, nonmetal
metal
have a high malleability
21. The three elements that are present in potassium carbonate, K2CO3 are
______________________________________________________________________________
22. Elements that are shiny solids, can be stretched and shaped, and good conductors of heat and electricity, are found
where on the periodic table?
______________________________________________________________________________
23. What type of element is copper?
______________________________________________________________________________
24. How many elements does CO2 have?
______________________________________________________________________________
25. Property used to distinguish between metals from other elements is that they
______________________________________________________________________________
26. The property of an element MOST helpful in determining its column on the periodic table is
______________________________________________________________________________
27. The formula for glucose is C6H12O6. How many elements does glucose contain?
______________________________________________________________________________
28. What is the atomic number for carbon and is it a metal or nonmetal?
______________________________________________________________________________
Classify each of the following elements as an alkali metal, an alkaline-earth metal, transition metal,
metalloid, halogen, or noble gas based on its position in the periodic table:
boron _______________________________________
gold _______________________________________
krypton
_______________________________________
calcium
_______________________________________
oxygen _______________________________________
How many valence electrons do each of the following elements have?


carbon ______
selenium ______


xenon ______
potassium ______
Determine how many atoms of each element are present in the molecules below:
CaF2 ______________________________________________________
Be(OH)2 ____________________________________________________
Al2(SO4)3 ___________________________________________________
NH4NO3 ____________________________________________________
S2F2 ______________________________________________________
Na2CO3 ____________________________________________________
Explain why oxygen is a fairly reactive element while neon is not.
Explain why beryllium loses electrons when forming ionic bonds, while sulfur gains electrons.
Explain why fluorine and chlorine have similar reactivities (the word “valence” should be somewhere in your
answer!)
Periodic Table Puns
Use your imagination and the elements in the Periodic Table to solve each pun!
Example: Five cents - Nickel, Ni
What you do in a play
What you do to a wrinkled shirt
"Tasty" part of your mouth
Someone who likes to start fires
Superman's weakness
Your brother or mine
Extinct
Imitation diamond
A type of flower
Las Vegas lights
Police
Golden State
Name of a goofy convìct
Mr. Mony's enemy
What you do to flowers
What you did to ripped jeans
A 'prize' element
A very smart person
Person from the big blue planet
A fur seller