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Regents Chemistry
Midterm Review
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Chemistry: ___Study of the structure, composition, and behavior of matter___ Metric System: based on powers of 10 – easier to convert! Example 1. Convert the following: 5.39 g = ___________ cg 87 nm = ___________ µm
Significant digits: Express how precise a number is Remember: all non-zeros are significant Zeros on the end of the number: Atlantic-Pacific Rule:
Remember! = ___________ have their densities listed on _________ __
Example 3:
1. A student measures the mass of a block of copper to be 43.2 g. If the measured dimensions are 0.50 cm x 2.4 x 4.3, what is the measured density?
2. What is the student’s percent error?
Key Idea: Measurement has a degree of _______________ and ______________.
Density:
% Error:
Rounding:
Multiplying/Dividing: Round by the NUMBER of significant digits Adding/Subtracting: Round to the DECIMAL PLACE
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Energy is the capacity to do _______ or produce ________.
Matter: has _________ and ____________.
The law of conservation of mass (and energy) states:
Kinetic Molecular Theory describes an __________ gas: Gas particles are in ____________, ___________, ____________ motion Gas particles are separated by ____________ distances relative to size. The volume of
particles is considered _____________. Gas particles have no ________________ forces between themselves. This occurs best
at _______ temperatures and _______ pressures. Collisions between the particles and the _______ of their containers create
___________ and are perfectly ___________ (transfer of energy).
In reality:
Key Idea: Temperature is a measure of __________ _________ __________. It can be expressed in either the __________ or ________ scales. Given by the formula __________________.
Key Idea: Kinetic Molecular Theory is a model that is used to explain the behavior of matter. It describes relationships among pressure, volume, temperature, velocity, frequency, and force of _____________.
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Combined gas law: Relates changes in the pressure, volume, and/or temperature of a gas
Avogadro’s Law:
Equal volumes of gas have the same number of particles
Dalton’s Law:
The total pressure is equal to the sum of the partial pressures
Graham’s Law:
The lighter a gas is, the faster it diffuses
Changes in Phase:
Melting Vaporization Sublimation Freezing Condensation Deposition
Key Idea: A heating curve demonstrates that during a phase change, the _____________ ___________ __________, or temperature, does not change. ____________ _____________ does change, however.
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Element Compound Mixture
Physical Property/Change
identity of the substance does NOT change
Examples:
Chemical Property/Change
identity of the substance DOES change
Examples:
Key Idea: Matter can be classified as an element, compound, or mixture. Elements and compounds are considered _____ ______________ because they consist of only one type of particle.
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Sample Problem: 1. Identify the type of substance (mixture, element, or compound) in each of the following
boxes of matter.
Separating Mixtures:
Filtration: Used to separate a solid from a liquid. WILL NOT SEPARATE A DISSOLVED
SUBSTANCE!
Distillation: Separates two liquids
based on different boiling points.
Crystallization: Separated a dissolved
substance (aq) from its solvent
Chromatography: Separates based on
polarity and solubility
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Dalton
Atoms are indivisible particles Reactions are a rearrangement of atoms
Thompson
Cathode ray tube Discovered presence of electrons / negative charges Plum pudding model: positive atom with electrons stuck on outside
Rutherford
Gold foil experiment – shot alpha particles at foil, expecting them to bounce off solid atoms Most went through – thus the atom is mostly empty space Some deflected – thus there is a small, dense positive nucleus
Bohr
Planetary model 7 rings – principal energy levels – of electrons orbiting Lowest energy closest to nucleus
Wave-Mechanical
Current model of thinking Electrons exist in areas of probability called orbitals, which are arranged in sublevels in the energy levels Electron behavior is described in probabilities
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Atomic Number: Number of protons (ID of element)
Atomic Mass: ______weighted average of naturally occuring isotopes___
Mass Number: ____mass of protons + neutrons__________________________
Isotope: _____same element, different number of neutrons____________
Ion: _______charged atom (lost or gained electrons)__________________
Ground State ____electrons are in lowest energy configuration (Closest to
nucleus)__
exCITED STATE ___an electron has jumped up an energy level__________
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Example 1:
1. Fill in the chart below with the missing information.
Symbol Protons Electrons Neutrons Atom/Ion
11 10 12
51 71 Atom
2. Which of the following is an excited atom?
a. 1s2 2s2 2p5 b. 1s2 2s2 2p63s1 c. 1s2 2s2 2p53s1 d. 1s2 2s2 2p4
3. Silicon has three naturally occurring isotopes: Si-28, Si-29, and Si-30. Each occurs in the following relative abundances: 92.21%, 4.70%, and 3.09%. What is the atomic mass?
Key Idea: Spectral lines are created by the ___________ of energy as electrons go from __________ state back to _________ state. Each element has unique __________________ so each produces a unique pattern.
Key Idea: The number of __________ gives the atom its ____________. Each element has a unique number of protons.
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Example 2:
1. Give the electron configurations (Bohr and sublevel), and draw the orbital diagram for each of the following:
a. An oxygen atom
b. A chlorine ion
2. The ‘mixture’ box is a mixture of which of
the two elements?
Remember: s and p blocks are the same as the period d is one behind f is two behind
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*The first shell can only hold 2 electrons, so for those elements the magic number is 2
Important Facts about the Periodic Table: ________________ developed one of the first tables, leaving spaces that _____________
the existence and properties of elements that had yet to be discovered
Rows are called PERIODS, columns are called GROUPS or FAMILIES
Elements are placed in order of increasing ____________ __________
The elements in a group have __________ ___________ due to the fact that each has the same number of _____________ _____________
The table can be split into 3 groups: metals, semimetals, and nonmetals.
Key Idea: The ________ rule states that all elements want ___ valence electrons. Metals tend to _____ electrons and nonmetals tend to _____ electrons to accomplish this.
Metals Nonmetals
Semimetals
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Atomic radius: distance from the nucleus to the outermost electron
Metallic Character: how easily atom loses an electron (reactive)
Electronegativity: attraction/affinity for electrons
Ionization Energy: energy required to remove an electron
+ ion: - ion: Example 1:
1. Which of the following would have a high melting point and be fairly malleable? a. Br b. B c. Be d. Bo
2. Which of the following is considered a metalloid? a. Al b. Si c. Po d. C
3. Which of the halogens would have the highest affinity for electrons? a. F b. Cl c. Br d. I
Atomic Radius Metallic Character
Electronegativity Ionization Energy
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4. Which atom has an ion with a smaller atomic radius than the parent atom? a. Ne b. Sb c. Ca d. N
Key Features of the Periodic Table:
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Lewis Dot Diagrams
Example 1. Draw the Lewis Dot Diagrams for the following:
Na Na ion
Chlorine Chlorine ion H2O K2O N2
CO2 F2 MgCl2
Key Idea: Atoms want a ________ _______ of valence electrons. Their bonding behavior is based on this tendency, and is the reason they will _____, _______, or ________ electrons.
Ionic Bonding:
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Network Covalent Bonding:
Allotrope: Example 2:
1. Which of the following is created by the equal sharing of electrons? a. K2O b. CaO c. N2O d. N2
2. Name each of the following:
a. MgO _______________________ d. Ag3PO4 ______________________ b. N2O5 _______________________ e. PbO2 ________________________ c. Fe2O3 _______________________ f. NO__________________________
3. Write the formulas for each of the following: a. Calcium fluoride __________ d. Silicon dioxide ___________ b. Cobalt II nitrate ___________ e. Zinc hydroxide ___________
Covalent Bonding:
Metallic Bonding:
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c. Lithium acetate ___________ d. Carbon tetrafluoride _______
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Shapes of Molecules
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Sample Problems: 1. Which of the following has a polar bond but is a
nonpolar molecule? a. N2 b. H2O c. NH3 d. CCl4
2. For each of the following: a. Draw the entire Lewis Dot Diagram, including unshared electrons. b. Identify the shape. c. Determine the polarity.
O2
Shape: Polarity:
HBr
Shape: Polarity:
H2O
Shape: Polarity:
BF3
Shape: Polarity:
NH3
Shape: Polarity:
CO2
Shape: Polarity:
CCl4
Shape: Polarity:
H2S
Shape: Polarity:
CH3Cl
Shape: Polarity:
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Intermolecular forces
3 general types: Dispersion Forces:
Dipole-Dipole:
Hydrogen Bonding:
Vapor Pressure:
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Chemical Reactions:
Table J Table F Example 1: Balance the following reactions.
_____Fe + _____Cl2 _____FeCl3
_____Ca(NO3)2 + _____AlPO4 _____Al(NO3)3 + _____Ca3(PO4)2 _____KMnO4 + _____HCl _____KCl + _____MnCl2 + _____H2O + _____Cl2
Identify the type of reaction. Pb(NO3)2 + 2KI PbI2 + 2KNO3
Fe + S FeS Mg + 2H2O Mg(OH)2 + H2
2H2O 2H2 + O2 For each of these reactions, identify if they would occur. Cu + HCl Na2SO4 + AgNO3 FeCl3 + F2 NH4C2H3O2 + Mg(OH)2