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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