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Atoms and their
Structure
Protons-positive
Electrons-negative
Neutrons-no charge
(neutral)
Models of the Atom
Bohr modelcompared electrons
to planets
• Because science is always
changing, we realized that
Bohr’s model could not
expl...
Electrons are found in
orbitals-behave like wavesquantum theory!
There are four kinds of
orbitals:
s orbitals
p orbitals
d...
Each orbital has a
different amount of
energy
Orbitals closer to the nucleus
have less energy than orbitals
further from t...
Valence Electrons
Electrons that are found in
the outermost energy level
of an atom
How do we know how many
valence electr...
The first orbital can hold
electrons

2

The second and third orbitals
can each hold 8 electrons
Higher orbitals are more
...
How many valence electrons
would an electrically neutral
Carbon atom have???
Carbon has 6 protons,
therefore an electrical...
Carbon’s first orbital can
only have 2 electrons
6 total electrons – 2
first shell electrons
leaves 4 electrons in
the out...
A Tour of the Periodic
Table
Periodic Law says:
1) Properties of elements
tend to change according
to a regular pattern when
those elements are
arrange...
What does this mean???
It means that elements with
certain characteristics in
common (like # of valence
electrons) are mor...
Periods and Groups

Horizontal Rows (leftright) are called
PERIODS

Handy for determining
valence shell electrons!!
Periods and Groups

Vertical columns (up-down) are
called GROUPS
All elements in a particular
group will have the same
num...
Atoms that have lost or
gained electrons are
called…IONS
Atoms that have lost or
gained neutrons are
called…ISOTOPES
Cation=atom that has
lost electrons, giving it
a positive charge
i.e. Li +
Anion=atom that has
gained electrons,
giving it...
Metals
-most elements are
metals
-good conductors of heat
and electricity
-most are fairly reactive
Metals continued

Alkali Metals-found in
Group 1
-Highly reactive
-one valence electron
-readily form cations
(+)
-not fou...
Alkaline Earth Metals

-Found in Group 2

-Very reactive, but not as
reactive as Alkali Metals
-2 valence electrons
-readi...
TRANSITION METALS
Groups 3-12
Can form more than one
cation, depending on what
they are bonding with
Very useful in techno...
Nonmetals
Found on the right side of the periodic
table
Very plentiful on earth-especially carbon,
silicon, oxygen, nitrog...
Halogens
-elements in Group 17
-very reactive, especially with alkali metals!
-7 valence electrons-only need ?? To have a ...
Noble Gases-Group 18
-Found in Group 18
-all inert gases
-full valence shells-do not need to get
any more electrons, there...
Semiconductors

Found on the “stairsteps”

Intermediate conductors of heat
and electricity-not as good as
metals, but bett...
Using Moles to Count Atoms
The mole is a counting unit, much like
“dozen” or “pair”
A dozen = 12 objects
A pair = 2 object...
Molar Mass
Average atomic mass is the mass of 1
atom
Molar mass is the mass of 1 mole of
atoms
The number is the same for ...
Conversion Factors
Just as we used a conversion factor to
do our metric conversions, we will use
a conversion factor to go...
More Conversion Factors
For our purposes, the conversion factor is
the molar mass of an element-found on
the periodic tabl...
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Atoms and the Periodic Table

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  • Transcript of "Ps ch 3_presentation"

    1. 1. Atoms and their Structure
    2. 2. Protons-positive Electrons-negative Neutrons-no charge (neutral)
    3. 3. Models of the Atom
    4. 4. Bohr modelcompared electrons to planets • Because science is always changing, we realized that Bohr’s model could not explain all of our observations!!
    5. 5. Electrons are found in orbitals-behave like wavesquantum theory! There are four kinds of orbitals: s orbitals p orbitals d orbitals f orbitals
    6. 6. Each orbital has a different amount of energy Orbitals closer to the nucleus have less energy than orbitals further from the nucleus
    7. 7. Valence Electrons Electrons that are found in the outermost energy level of an atom How do we know how many valence electrons a particular atom has???
    8. 8. The first orbital can hold electrons 2 The second and third orbitals can each hold 8 electrons Higher orbitals are more complicated and will be learned in Chemistry class!
    9. 9. How many valence electrons would an electrically neutral Carbon atom have??? Carbon has 6 protons, therefore an electrically neutral atom would need 6 electrons to balance the charge
    10. 10. Carbon’s first orbital can only have 2 electrons 6 total electrons – 2 first shell electrons leaves 4 electrons in the outer shell (valence shell)
    11. 11. A Tour of the Periodic Table
    12. 12. Periodic Law says: 1) Properties of elements tend to change according to a regular pattern when those elements are arranged by increasing atomic number!!
    13. 13. What does this mean??? It means that elements with certain characteristics in common (like # of valence electrons) are more likely to have similar chemical properties (like what kinds of atoms they react with!)
    14. 14. Periods and Groups Horizontal Rows (leftright) are called PERIODS Handy for determining valence shell electrons!!
    15. 15. Periods and Groups Vertical columns (up-down) are called GROUPS All elements in a particular group will have the same number of valence electrons, which gives them all similar chemical properties
    16. 16. Atoms that have lost or gained electrons are called…IONS Atoms that have lost or gained neutrons are called…ISOTOPES
    17. 17. Cation=atom that has lost electrons, giving it a positive charge i.e. Li + Anion=atom that has gained electrons, giving it a negative charge i.e. Cl -
    18. 18. Metals -most elements are metals -good conductors of heat and electricity -most are fairly reactive
    19. 19. Metals continued Alkali Metals-found in Group 1 -Highly reactive -one valence electron -readily form cations (+) -not found naturally in nature-why?
    20. 20. Alkaline Earth Metals -Found in Group 2 -Very reactive, but not as reactive as Alkali Metals -2 valence electrons -readily form cations (+2) -too reactive to be found alone in nature
    21. 21. TRANSITION METALS Groups 3-12 Can form more than one cation, depending on what they are bonding with Very useful in technology and economy
    22. 22. Nonmetals Found on the right side of the periodic table Very plentiful on earth-especially carbon, silicon, oxygen, nitrogen, and sulfur Readily form anions by gaining electrons to form full outer shells
    23. 23. Halogens -elements in Group 17 -very reactive, especially with alkali metals! -7 valence electrons-only need ?? To have a full shell… -form anions (-1) by GAINING that one missing electron
    24. 24. Noble Gases-Group 18 -Found in Group 18 -all inert gases -full valence shells-do not need to get any more electrons, therefore they do not react with other atoms or elements -will not form ions
    25. 25. Semiconductors Found on the “stairsteps” Intermediate conductors of heat and electricity-not as good as metals, but better than nonmetals Classified as nonmetals, but have some properties of metalssometimes called “metalloids”
    26. 26. Using Moles to Count Atoms The mole is a counting unit, much like “dozen” or “pair” A dozen = 12 objects A pair = 2 objects A mole = 6.022 x 10 23 objects 6.022 x 10 23 is known as Avogadro's constant
    27. 27. Molar Mass Average atomic mass is the mass of 1 atom Molar mass is the mass of 1 mole of atoms The number is the same for both of these and can be found on the periodic table, usually under the Chemical symbol for that particular element The only difference for these two values is the unit you use -Atomic Mass Unit vs grams/mole
    28. 28. Conversion Factors Just as we used a conversion factor to do our metric conversions, we will use a conversion factor to go from moles → mass and mass → moles
    29. 29. More Conversion Factors For our purposes, the conversion factor is the molar mass of an element-found on the periodic table So... 1 mole Carbon = 12.011 grams 12.011 grams Carbon = 1 mole
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