Post on 05-Jan-2016
transcript
“Whether you think you can, or you think you can’t - you’re right.”
- Henry Ford
Review ofChapter 1: The Atom
History of Atomic Theories
Parts of an AtomNucleus
Protons: positive charge, mass = 1 amu Neutrons: no charge, mass = 1 amu
Electrons Negative charge, mass = 0 amu Valence e- are the outermost ones Located somewhere in orbitals, regions of e-
density
amu is an “atomic mass unit”, a unit of weight
Remember: # protons = # electrons in uncharged atoms
Atomic Number
Atomic number is
# of protons
(and # of electrons)
Mass number is
# of protons and
neutrons combined, gives “weight” of atom
Isotopes
Isotopes are different versions of the same element Same atomic number (# protons) Different mass number (from different # neutrons)
H-1 H-2 H-3
Calculating Atomic Mass
(amu-1)(%1) + (amu2)(%2) + (amu3)(%3) + …
Electron Locations
Electrons are in orbitalsGround state is the
lowest levelElectrons can absorb
energy and move to a higher level, or excited state
Release energy as they drop back down
Review ofChapter 2: Formulas
and Equations
Formula BasicsSymbols identify elements: K, Na, O, F, Mg, SbFormulas give info from symbols and numbers
NaCl NH3 CH3Br
Qualitative info can’t be counted (quality). Ex: what elements are present
Quantitative info can be counted (quantity). Ex: how much of each element?
Writing Formulas
Coefficients are written in front of a formula, tells how many of the formula there are
3 CO2 5 H2O 8 NH3
Subscripts are small, after symbols, and tell how many atoms there are of each element
3 CO2 5 H2O 8 NH3
Ions
Uncharged atoms have same #
of protons and electronsIons are atoms that lose or gain electrons,
become charged:
Cl-, Na+, Cu Polyatomic ions are charged molecules:
NH4+, SO4 , NO3-
2+
2-
Equalizing Charges
Naming Compounds
Ionic (M/NM) compounds: use name of (+) element (metal), change end of (-) nonmetal to “-ide.” Ex: NaCl = Sodium chloride
Polyatomic ions keep their namesCovalent (NM/NM) compounds: less
electronegative atom written first, each is named with “mono-, di-, tri-, tetra-” prefixes. Ex: N2O4 = Dinitrogen tetroxide
Roman Numerals in Names
Use a numeral in names when an atom has several options of what its charge can be
Copper (III) sulfate means the copper atom has a +3 charge, as opposed to other possible charges. Cu2(SO4)3
Lead (II) nitrate = Pb(NO3)2
Ch-ch-ch-changes
Physical changes affect form of starting material, but stays same substance Cheese melting, chopping wood
Chemical changes produce new substances Burning wood, mixing acid & base
Chemical Reaction Equations
Reactant + Reactant Product + Product
HCl + NaOH H2O + NaCl
Law of Conservation of Mass says whatever’s on the left needs to be on the right, nothing created or destroyed
4 Types of ReactionsAddition: A + B C
Things come together
Decomposition: C A + B Something breaks apart
Single Replacement: AB + C A + BC Part of a compound is replaced
Double Replacement: AB + CD AD + BC All the pieces of a compound switch around