The Wave-Mechanical Model of an Atom: Key Concepts and Properties
Concepts in the Wave-Mechanical Model
Which statement describes a concept included in the wave-mechanical model of an atom?
Electrons are located in regions called orbitals.
Isotopes and Atomic Structure
Two atoms that are different isotopes of the same element have
the same number protons, different number neutrons.
Chemical Properties and Classification
The element in Group 14, Period 3, of the Periodic table is classified as a
metalloid (on or below the steps).
Chemical Similarities and Properties
Which element has chemical properties that are most similar to potassium? (Choices: Cs, Ca, N, S)
Cesium (same group = similar properties).
Ionization Energy and Electron Removal
Which element requires the least amount of energy to remove the most loosely held electron from a gaseous atom in ground state? (Choices: Na, Ar, P, Cl)
Na (lowest ionization energy).
Compound Categories and Bonding
Which terms identify two different categories of compounds?
ionic and molecular.
Bond Formation and Energy Changes
Which statements describes the energy and bonding changes as two atoms of fluorine become a molecule of fluorine?
Energy is released as a bond is formed.
Atomic Structure and Lewis Diagrams
Which part of a calcium atom in ground state is represented by the dots in its Lewis electron-dot diagram?
the electrons in the fourth shell (valence electrons).
Chemical Attraction and Electronegativity
Based on Table S, an atom of which element has the strongest attraction for electrons in a chemical bond?
Chlorine (highest electronegativity).
Chemical Decomposition and Nature of Substances
Which substance can not be broken down by chemical means?
aluminum (because it's an element).
Kinetic Molecular Theory and Gaseous Particles
Which statement describes the particles of an ideal gas, based on the kinetic molecular theory?
The volume of the gas particles is negligible compared with the total volume of the gas.
Heat and Phase Changes
What is the amount of heat released by 1.00 gram of liquid water at degrees Celsius when it changes to a 1.00 gram of ice at 0 degrees Celsius?
334 J (Heat of Fusion).
Intermolecular Forces and Bonding
Which term identifies a type of intermolecular force?
hydrogen bonding.
Chemical Equilibrium and Reactions
Which statement describes a reaction at equilibrium?
The rate of formation of the products must equal the rate of formation of the reactants.
Entropy and Energy Changes
Entropy is a measure of
disorder of a system.
Chemical Reactions and Nature's Direction
Systems in nature tend to undergo change toward
lower energy and greater randomness.
Acid-Base Chemistry and Identification
Which compound is an Arrhenius base? (Choices: HCl, H3PO4, Ca(OH)2, CH3COOH)
Ca(OH)2 (because base = OH).
Neutralization Reactions and Product Formation
In a neutralization reaction, an aqueous solution of an Arrhenius acid reacts with an aqueous solution of an Arrhenius base to produce
a salt and water.
Acid-Base Theories and Definitions
According to one acid-base theory, a base is an
H+ acceptor.
Radioactivity and Nuclear Properties
Based on Table N, uranium-238 and uranium-235 have different
half-lives.
Nuclear Transformations and Elements
A change in the nucleus of an atom that converted the atom from on element to another element is called
transmutation.
Radiation Types and Properties
Which radioactive emission has the greatest penetrating power but the least ionizing power?
gamma ray.
Fission Reactions and Energy Production
Which statement describes a benefit of using fission reactions?
Large amounts of energy are produced per mole of reactant.
Atomic Mass and Identification
Which atom has a mass of 12u?
E.
Excited States and Electron Configurations
Which electron configuration could represent the electrons in a sodium atom in an excited state?
2-7-2.
Valence Electrons and Atomic Properties
What is the number of valence electrons in a nitrogen atom in the ground state?
5.
Carbon Forms and Structure
Graphite and diamond are both solid forms of the element carbon. Which statement explains the different properties of these two forms of carbon?
Diamond has a different crystal structure from graphite.
Atomic Radius and Error Calculation
A measured value for the atomic radius of platinum atoms was determined to be 143 picometers. Based on Table S, what is the percent error of this measured value?
10%.
Chemical Formulas and Compounds
What is the chemical formula for sodium oxalate?
Na2C2O4.
Molecular Formula and Composition
What is the molecular formula for this compound?
C3H6.
Types of Chemical Reactions
Which equation represents a single replacement reaction?
2Al + 6HCl --> 2AlCL3 + 3H2.
Chemical Bonds and Polarity
The bond between which two atoms is most polar?
H-O (greatest difference in electronegativities).
Gas Samples and Comparison
Which two gas samples contain equal numbers of atoms?
Helium and Argon.
Chemical Equilibrium and System Changes
What occurs when Na2SO4 is added to this system, increasing the concentrations of SO4 2-?
Heat of Reaction and Enthalpy
Which numbered interval represents the heat of reaction?
2.
Metal Activity and Reactivity
Based on Table J, which metal is more active than tin, but less active than zinc? (Choices: Ag, Cr, Cs, Mn)
Cr.
Concentration Measurements and Solutions
What is the concentration of the KOH solution?
0.0250 M.
Chemical Elements and Identification
What is the unidentified element?
L.