Transcript Physical Science Review #1

Physical Science Review #2
Atom, Periodic Table, Lewis Dot
Structures, Mole
Atom Basics
• Atom: smallest unit of matter
– Composed of 3 subatomic particles
• In the nucleus
– Protons (positive charge)
– Neutrons (neutral charge)
• Outside Nucleus
– Electrons (negatively charged)
– Stays together because of the Positive and
negative attraction between protons and electrons
– Isotopes: atoms of the same element with
difference masses because of different number of
neutrons
Calculating Atom Stuff
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Atomic # = # Protons
Atomic Mass = # Protons + # Neutrons
# protons = Atomic # = # electrons if no charge
# neutrons= Mass # - # protons
# protons = Atomic # = # Electrons = Mass - #n
# electrons = # protons
Bohr Models
• Inside nucleus you write # p & # n
• Outside you draw your electron orbitals.
– 1st level can only hold 2 electrons
– 2nd level can hold up to 8
• # of valence electrons = # electrons in outside
shell
Periodic Table Basics
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YOU MUST KNOW YOUR ELEMENTS!
Rows = Periods
Columns = Groups
# of valence electrons = Group #
Group 1 = Alkali Metals = Most reactive group
Group 2 = Alkaline Earth Metals
Middle = Transition Metals
Group 7= Halogens
Group 8 = Noble Gases = Least reactive group
Periodic Table Basics
• There are mostly metals on the periodic table
(left side of metalloids)
• 6 metalloids (B, Si, Ge, As, Sb, Te)
• Non metals are on the Right side of metalloids
• Hydrogen is the only nonmetal on the left side
of the periodic table
Lewis Dot Structures
• Show the # of valence electrons
• For single element, write element then dots
around. (start with single dots at top, bottom,
left, right, then double up your dots)
Lewis Dot Structures: Compounds
• When drawing Lewis Dot Structures for
Compounds Use the NASL method.
• Remember all elements except H & He Need
8, H & He need 2
• A is how many valence electrons are available
• S is how many are shared (N-A) this tells you
how many electrons are in bonds (2 electrons
per bond)
• L is # of lone dots
Lewis Dot: Charged Compounds
• On the A Step:
– Add the number of charge if it is negatively charged
– Subtract the number of charge if positively charged
Using the Mole
• Use train tracks to go from grams to mole or
moles to grams.
• To figure out how many grams in 1 mole, use
the periodic table mass
• Ex. Change 20 moles of carbon to g.
Other
• # of Atoms = How many of each type of
element you have (In P2O6 you have 8 total
atoms)
• # of molecules how many of the compound
you have: 8 H2O2 = 4 atoms, 8 molecules)
Find the mass of Compounds
Steps:
1. Write down the elements you have
2. Write down how many you have of each
3. Look up the mass of each element
4. Multiple your mass by how many you have
5. Add up all totals.
Example: Find the mass of C2O3