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Atomic Structure and<br />
the Periodic Table<br />
1. Students can describe the parts of an atom<br />
2. Students can read the element information on<br />
the periodic table<br />
3. Students can describe the reactivity of alkali<br />
metals<br />
4. Students can describe how various types of<br />
bonding in different categories of materials<br />
effects their behavior
Atoms<br />
• smallest particle of an element that has<br />
the properties of the element<br />
• made of 3 basic subatomic particles<br />
• there are now many more subatomic particles<br />
– theoretical physics
• nucleus<br />
• small, dense center of atom<br />
• contains almost all the mass of the atom<br />
• contains protons and neutrons
• Atomic Mass Unit (amu)<br />
• metric unit to measure the mass of VERY<br />
small objects (particles)<br />
• a unit to measure the mass of atoms
Subatomic Particles<br />
Name Protons (p or +) Neutrons (n) Electrons (e - )<br />
Charge +1 No charge -1<br />
Location in nucleus in nucleus in shells around<br />
nucleus<br />
Mass ≈ 1 amu ≈ 1 amu ≈ 2000 x<br />
smaller<br />
“Job”<br />
Determines<br />
identity of<br />
element<br />
Supplies proper<br />
mass to hold<br />
nucleus together<br />
Determines<br />
bonding/<br />
how it reacts<br />
Number
Subatomic Particles<br />
Name Protons (p or +) Neutrons (n) Electrons (e - )<br />
Charge +1 No charge -1<br />
Location in nucleus in nucleus in shells around<br />
nucleus<br />
Mass ≈ 1 amu ≈ 1 amu ≈ 2000 x<br />
smaller<br />
“Job”<br />
Determines identity<br />
of element<br />
Supplies proper<br />
mass to hold<br />
nucleus together<br />
Determines<br />
bonding/ how it<br />
reacts<br />
Number Atomic # Atomic mass –<br />
atomic # =<br />
# of neutrons<br />
Same as #<br />
of protons
# of protons<br />
• atomic number<br />
• whole number on periodic table<br />
• number of protons in an atom of an element<br />
• does NOT vary in an element – the same in<br />
all atoms of an element
# of electrons<br />
• atoms are neutral<br />
• (+) = (-)<br />
• # of protons = # of electrons<br />
• p = e -
• atomic mass (weight)<br />
• decimal number on the periodic table – it is<br />
for all the atoms of the element<br />
• number of protons plus the number of<br />
neutrons – it’s an average on the table<br />
• weighted average of all the isotopes of<br />
that element<br />
• the mass of one atom is a whole number
• Isotopes<br />
• iso = same<br />
• atoms of the same element with different<br />
numbers of neutrons<br />
• have different atomic masses but the same<br />
atomic number<br />
• some are stable, some are radioactive<br />
(carbon-12 and carbon-14)
Free Write<br />
• What do you know about:<br />
• atoms<br />
• the periodic table
Periodic Table<br />
• How is the periodic table arranged?<br />
• arranged by increasing atomic number<br />
• rows<br />
• called periods<br />
• tells number of electron shells<br />
• number them down the left side of the<br />
periodic table – 1 through 7
Periodic Table<br />
• columns<br />
• called families or groups<br />
• elements in same column have similar<br />
chemical properties<br />
• same number of valence electrons
Ion<br />
• atom with a charge<br />
• atom has gained or lost electrons<br />
• gained e - = (-) charge<br />
• lost e - = (+) charge<br />
• (+) ion = cation<br />
• (-) ion = anion
Column 1<br />
• alkali metals<br />
• want to give away one electron<br />
• most reactive metals
Alkali metals on the show<br />
brainiac
Bonding<br />
• atoms achieve a stable number of<br />
electrons (ionic and covalent)<br />
• involves valence (outer) electrons<br />
• make compounds and/or solids
Metallic Bonding<br />
All pure metals have metallic bonding and<br />
therefore exist as metallic structures. Metallic<br />
bonding consists of a regular arrangement of<br />
positive ion cores of the metals surrounded by a<br />
mobile delocalized sea of electrons.
Metallic Bonding<br />
• Each atom donates its valence electrons to<br />
the whole<br />
• Atom therefore becomes a cation (here called<br />
an ion core)<br />
• Donated electrons form an electron cloud<br />
surrounding all the ion cores<br />
• Electron cloud binds all the ion cores together<br />
by coulombic forces
Metallic Bonding<br />
• Valence electrons are delocalized:<br />
• Shared by all atoms in the material<br />
• Electrons are free to drift throughout the<br />
material<br />
• Provides unique properties only found in<br />
metals<br />
• shiny metallic luster<br />
• good electrical and thermal conductivity<br />
• many others ...
Metallic Bonds: Mellow dogs with plenty of<br />
bones to go around<br />
These bonds are best imagined as a room full of<br />
puppies who have plenty of bones to go around and<br />
are not possessive of any one particular bone. This<br />
allows the electrons to move through the substance<br />
with little restriction. The model is often described<br />
as the "kernels of atoms in a sea of electrons."
Ionic Bonding<br />
(ceramics and polymers)
Ionic Bonds: One big greedy thief dog!<br />
Ionic bonding can be best imagined as one big greedy<br />
dog stealing the other dog's bone. If the bone<br />
represents the electron that is up for grabs, then when<br />
the big dog gains an electron he becomes negatively<br />
charged and the little dog who lost the electron<br />
becomes positively charged. The two ions (that's where<br />
the name ionic comes from) are attracted very strongly<br />
to each other as a result of the opposite charges.
Sodium lets Chlorine use its valance electron
Covalent Bonding<br />
(Ceramics)
Covalent Bonds: Dogs of equal strength.<br />
Covalent bonds can be thought of as two or more dogs<br />
with equal attraction to the bones. Since the dogs<br />
(atoms) are identical, then the dogs share the pairs of<br />
available bones evenly. Since one dog does not have<br />
more of the bone than the other dog, the charge is<br />
evenly distributed among both dogs. The molecule is not<br />
"polar" meaning one side does not have more charge than<br />
the other.
Polar Covalent Bonds: Unevenly matched but<br />
willing to share.<br />
These bonds can be thought of as two or more dogs that<br />
have different desire for bones. The bigger dog has<br />
more strength to possess a larger portion of the<br />
bones. Sharing still takes place but is an uneven<br />
sharing. In the case of the atoms, the electrons spend<br />
more time on the end of the molecule near the atom<br />
with the greater electronegativity (desire for the<br />
electron) making it seem more negative and the other<br />
end of the molecule seem more positive.
• http://www.bbc.co.uk/scotland/education/bitesize/higher/<br />
chemistry/energy/bsp1_rev.shtml<br />
• Read the 4 slides and take the quiz at the end<br />
• Patterns in the periodic table<br />
• http://www.ewart.org.uk/science/structures/str13.htm<br />
• Ionic bonding Electron numbers ions and aions<br />
• http://www.ewart.org.uk/science/structures/str14.htm<br />
• Covalent bonding<br />
• http://www.ewart.org.uk/science/structures/str7.htm<br />
• Structure of the atom