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Questions and Answers
If the temperature of a gas in a closed container increases, which of the following properties will also increase, assuming amount of gas remains unchanged?
If the temperature of a gas in a closed container increases, which of the following properties will also increase, assuming amount of gas remains unchanged?
A gas is at a temperature of 27°C. What is the temperature in Kelvin?
A gas is at a temperature of 27°C. What is the temperature in Kelvin?
Which of the following represents the correct relationship between the volume and amount of gas, according to Avogadro's law?
Which of the following represents the correct relationship between the volume and amount of gas, according to Avogadro's law?
Which of the following best explains why vegetable oil does not dissolve in water?
Which of the following best explains why vegetable oil does not dissolve in water?
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Which of the following gases is considered a triatomic gas?
Which of the following gases is considered a triatomic gas?
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Which scientist is credited with discovering the existence of electrons?
Which scientist is credited with discovering the existence of electrons?
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What is the atomic theory formulated by John Dalton based on?
What is the atomic theory formulated by John Dalton based on?
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According to Niels Bohr's model, what is emitted when an electron jumps from a higher energy level to a lower one?
According to Niels Bohr's model, what is emitted when an electron jumps from a higher energy level to a lower one?
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What is the ground state of an electron in an atom?
What is the ground state of an electron in an atom?
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What is the primary characteristic of alkali metals concerning their reactivity?
What is the primary characteristic of alkali metals concerning their reactivity?
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Which description best characterizes transition metals?
Which description best characterizes transition metals?
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What does an Atomic Mass Unit (amu) represent?
What does an Atomic Mass Unit (amu) represent?
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Which of the following is a key property of Alkaline Earth Metals?
Which of the following is a key property of Alkaline Earth Metals?
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Which of the following statements accurately describes the relationship between electronegativity and atomic radius within a period?
Which of the following statements accurately describes the relationship between electronegativity and atomic radius within a period?
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What is the primary reason why covalent compounds generally have lower melting points compared to ionic compounds?
What is the primary reason why covalent compounds generally have lower melting points compared to ionic compounds?
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What happens to the electron affinity of an atom as you move down a group on the periodic table?
What happens to the electron affinity of an atom as you move down a group on the periodic table?
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Which of the following best describes the role of a surfactant?
Which of the following best describes the role of a surfactant?
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In a polar covalent bond which is represented by a dipole, which of the following is true?
In a polar covalent bond which is represented by a dipole, which of the following is true?
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When a metal nitrate is heated, what products are formed?
When a metal nitrate is heated, what products are formed?
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Which of the following is NOT a characteristic of noble gases?
Which of the following is NOT a characteristic of noble gases?
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If the electronegativity difference (ΔEN) between two bonded atoms is 1.2, what type of bond is most likely formed?
If the electronegativity difference (ΔEN) between two bonded atoms is 1.2, what type of bond is most likely formed?
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What does the formula $Z_{eff} = Z - S$ represent?
What does the formula $Z_{eff} = Z - S$ represent?
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Which of the following best describes London dispersion forces?
Which of the following best describes London dispersion forces?
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An acid that doesn't contain oxygen, such as $HCl$, is named using which prefix/suffix?
An acid that doesn't contain oxygen, such as $HCl$, is named using which prefix/suffix?
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What causes the increased acidity of oceans due to climate change?
What causes the increased acidity of oceans due to climate change?
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Which of the following factors would NOT typically increase the rate of dissolving a solid in a liquid?
Which of the following factors would NOT typically increase the rate of dissolving a solid in a liquid?
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According to kinetic molecular theory, what is the relationship between the average kinetic energy of gas molecules and temperature?
According to kinetic molecular theory, what is the relationship between the average kinetic energy of gas molecules and temperature?
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What are the main types of motion that gas molecules exhibit?
What are the main types of motion that gas molecules exhibit?
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Study Notes
Atomic Theory and Structure
- Dalton's Atomic Theory: Proposed that elements are composed of indivisible particles called atoms; atoms of the same element are identical; atoms of different elements are different; atoms combine to form new substances; atoms cannot be created or destroyed.
- JJ Thomson's Discovery: Discovered electrons, negatively charged particles within the atom, using a cathode ray tube.
- Niels Bohr's Theory: Proposed that electrons orbit the nucleus in specific energy levels; electrons absorb or emit energy when transitioning between levels.
Atomic Structure - Energy Levels
- Bohr's Energy Levels: Electrons orbit the nucleus at defined energy levels (lowest energy in level 1); electrons can transition between levels by gaining or losing energy; filling order: 1st, then 2nd and 3rd
- Light Wavelength: Color of light emitted or absorbed depends on the specific energy levels electrons jump between (electron transitions)
Atomic Mass Unit (amu)
- Atomic Mass Unit (amu): A unit of mass equal to 1/12 the mass of a carbon-12 atom.
Elements and Properties
- Alkali Metals: Shiny, soft, solids at room temperature; highly reactive; always bonded with another element in nature
- Alkaline Earth Metals: Light, highly reactive metals; react with oxygen to form oxides; solid at room temperature.
- Transition Metals: Form multivalent ions; variable reactivity; good conductors of heat and electricity; many react with oxygen to make oxides.
- Halogens: Can be solid, liquid or gas; dull; non-conductors; highly reactive.
- Noble Gases: Colorless gases; extremely unreactive; low melting & boiling points; found in Earth's atmosphere.
Effective Nuclear Charge (Zeff)
- Effective Nuclear Charge (Zeff): The net positive charge experienced by an electron in an atom, taking into account the shielding effect of inner electrons. Formula: Zeff = Z - S (Z = number of protons, S = number of core electrons)
Electron Affinity
- Electron Affinity: The energy change associated with adding an electron to a gaseous atom. Multiple electron affinities exist for adding multiple electrons.
- Trend Down a Group: Decreases as the attraction between the nucleus and an added electron decreases and shielding increases.
- Trend Across a Period: Increases as the attraction between the nucleus and an added electron increases.
Electrolytes
- Electrolytes: Substances that form an electrically conductive solution when dissolved.
- Ionic Compounds as Electrolytes: Ionic compounds are electrolytes because their ions dissociate in water, allowing them to carry charge through the solution.
Covalent Compounds and Melting Points
- Low Melting Points of Covalent Compounds: Covalent compounds, despite having tightly bonded atoms, often have weak intermolecular forces, resulting in low melting points.
Electronegativity
- Electronegativity: The ability of an atom to attract bonding electrons.
- Trend Across a Period: Increases as atomic radius decreases and the attraction between valence electrons and the nucleus increases (additional protons).
- Trend Down a Group: Decreases as atomic radius increases and the attraction between valence electrons and the nucleus weakens.
Electronegativity Difference
-
Electronegativity Difference (ΔEN): The difference in electronegativity between two atoms. This difference determines the type of bond:
- Less than 0.5: Nonpolar covalent
- 0.5 - 1.7: Polar covalent
- Greater than 1.7: Ionic
Dipole
- Dipole: Separation of positive and negative charges within a polar molecule, creating positive and negative poles, indicated by δ+ and δ- respectively and the arrowhead points to the negative pole.
Intermolecular Forces
- Dipole-Dipole Forces: Attraction between the positive end of one polar molecule and the negative end of another. Strongest in polar molecules.
- London Dispersion Forces: Temporary, weak attractions between nonpolar molecules due to temporary shifts in electron cloud distribution. Present in all molecules, weaker than dipole-dipole forces unless the nonpolar molecule is very large.
- Hydrogen Bonding: Strong dipole-dipole force between molecules with a hydrogen atom bonded to a highly electronegative atom (N, O, or F).
Chemical Equations
- Nomenclature Rules and Patterns (Per-, -ate → -ite, Hypo-): Predicting formulas for and naming chemical compounds of different oxidation states.
- Common Chemical Reactions (Metal replacement): Including metal displacement from water, oxides, and acid reactions.
- Acid Rain: Caused by nitrogen and sulfur oxides reacting with water, creating nitric or sulfuric acid.
Stoichiometry
- Empirical Formula: Determining the simplest whole-number ratio of atoms in a compound.
- Molecular Formula: Finding the actual number of atoms in a molecule.
- Hydrate: Determining the ratio of water molecules to the ionic compound in a hydrate.
- Limiting and Excess Reactants: Determining the reactant that limits product formation.
- Percent Yield: Comparing actual yield of a product to its theoretical yield.
Reactions and Rates
- Rates of Dissolution: Affected by temperature, agitation, and particle size.
- Factors Affecting Solubility: Temperature, pressure, size of solute particle.
Solutions
- Surfactants: Compounds that reduce surface tension by breaking down hydrogen bonds at the surface, enabling polar solvents to dissolve nonpolar liquids.
Acids and Bases
- Naming Acids: Differentiating acids without and with oxygen.
Gases
- Kinetic Molecular Theory: Describing the behavior of gases at the molecular level, average kinetic energy dependent on temperature.
- Gas Laws: Boyle's law (P & V), Charles's law (V & T), Gay-Lussac's law (P & T), Ideal gas law (PV=nRT).
- Gas Stoichiometry: Applying gas laws to chemical reactions.
Periodic Table
- Periodic Table Arrangement: Mendeleev based it on atomic mass; Moseley suggested arranging it by atomic number.
- Periodic Trends: Elements in the same group have similar chemical properties due to similar numbers of valence electrons.
Solubility in Water
- NaCl: Highly soluble due to ionic nature and interaction with water molecules.
- Glucose: Soluble due to hydrogen bonding with water.
- Vegetable Oil: Insoluble due to nonpolar nature, inability to interact with polar water.
- Monatomic, Diatomic, Triatomic gases: Describing gases based on the number of atoms in a molecule.
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Description
Test your knowledge on atomic theory with questions covering Dalton's Atomic Theory, JJ Thomson's discoveries, and Bohr's energy levels. Dive into the structure of atoms and the principles governing electron transitions. This quiz is designed for students studying chemistry concepts in depth.
