Questions and Answers
Why are there exceptions to the electron configuration rules?
Exceptions to the Aufbau principle are based on the fact that a few atoms are more stable when their electrons fill or half-fill an electron shell or subshell.
Define electron configuration.
The distribution of electrons of an atom or molecule in atomic or molecular orbitals.
How was the periodic table arranged in the past?
Based on physical properties.
Who is Johann Dobereiner?
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What is the Halogen Triad?
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What does the Law of Octaves propose?
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Who published a table of the elements organized by increasing atomic mass?
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Who is Lothar Meyer?
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Why is Mendeleev called the 'father of the modern periodic table'?
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What is the role of Henry Moseley in periodic table development?
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What did Glenn T. Seaborg do?
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What is the periodic law?
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What are periods in the periodic table?
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What are groups or families in the periodic table?
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What is a chemical symbol?
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Define atomic number.
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What is atomic mass?
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What are valence electrons?
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How many valence electrons can an atom have?
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What are valence electrons used for?
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How do you determine the number of valence electrons?
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What kind of elements make up most of the periodic table?
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What are metalloids?
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List the properties of metals.
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What are the properties of nonmetals?
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What are the properties of metalloids?
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What is a semiconductor?
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When does atomic radius increase on the periodic table of elements?
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Why does atomic radius increase in columns?
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When does atomic radius decrease on the periodic table?
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Why does atomic radius decrease across a period?
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What is electron shielding?
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When is an atom 'ionized'?
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If an atom loses an electron, what happens?
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If an atom gains an electron, what happens?
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What is ionization energy?
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What happens if an atom is larger?
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Are ionization energy and atomic radius directly or inversely proportional?
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What is electron affinity?
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What is metallic character?
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Define electronegativity.
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What is the unit for electronegativity?
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How does electronegativity work on the periodic table?
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What is the overall reactivity trend for metals?
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What is the overall reactivity trend for nonmetals?
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What is the octet rule?
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What is an anion?
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What is a cation?
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What is the ionic radius for cations?
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What is the ionic radius for anions?
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What are noble gases?
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What are alkali metals?
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What are alkaline earth metals?
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What are transition elements?
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What are lanthanides?
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What are actinides?
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What are main block elements?
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What are halogens?
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What are chalcogens?
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What properties do noble gases exhibit?
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What defines hydrogen's unique position on the periodic table?
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What is the shielding effect with ionization energy?
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What is the Heisenberg uncertainty principle?
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What are the electron cloud levels?
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How many principal energy levels are there?
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What are subshells and orbitals?
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Where does the modern quantum mechanical model come from?
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What is an atomic orbital?
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What is the shape of an s orbital?
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What is the shape of a p orbital?
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What are the number of electrons for the first four energy levels?
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What does the Aufbau principle state?
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Which groups have filled s orbitals?
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Which groups have filled p orbitals?
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Which groups have filled d orbitals?
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Which groups have filled f orbitals?
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How to abbreviate electron configurations?
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Why are there electron configurations that are exceptions?
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What is the d^4 and d^9 rule?
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What is the Pauli Exclusion Principle?
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What is Hund's Rule?
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What is the order of electron configuration?
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What are quantum numbers?
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What is the principal quantum number?
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What is the angular momentum (azimuthal) quantum number?
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What does the magnetic quantum number indicate?
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What is the spin quantum number?
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What are subshells?
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What defines a nonpolar covalent bond?
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What defines a polar covalent bond?
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What defines an ionic bond?
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Study Notes
Electron Configuration and Principles
- Exceptions to the Aufbau principle arise from stability preferences in electron configurations, particularly in transition metals like copper and chromium.
- Electron configuration refers to the distribution of electrons in an atom's orbitals.
- The atom's electron arrangement is essential to understanding its chemical properties and reactivity.
Historical Periodic Table Arrangements
- Initially, the periodic table was organized based on physical properties rather than atomic structure.
- Johann Dobereiner classified elements into triads based on similar properties, like the halogen triad: chlorine, bromine, and iodine.
- John Newlands introduced the Law of Octaves, suggesting that properties repeat every eighth element according to atomic mass.
- Dmitri Mendeleev created a periodic table by increasing atomic mass, predicting undiscovered elements and their properties.
Key Figures in Periodic Table Development
- Lothar Meyer produced a similar table to Mendeleev's around the same time.
- Henry Moseley rearranged the periodic table by increasing atomic number, solidifying the modern organization.
- Glenn T. Seaborg advanced the table by moving 14 elements to create the Actinide series and co-discovered ten new elements.
Structure of the Periodic Table
- The periodic law states that the properties of elements are periodic functions of their atomic numbers.
- Elements are arranged into rows (periods) and vertical columns (groups/families).
- Chemical symbols are one or two-letter abbreviations derived from Greek or Latin names.
Atomic Characteristics
- Atomic number indicates the number of protons or electrons in an atom.
- The atomic mass is the sum of protons and neutrons in the nucleus.
- Valence electrons are crucial for chemical bonding, with atoms typically having 1 to 8 in their outermost shell.
Trends in the Periodic Table
- Atomic radius increases down a group due to the addition of energy levels, and decreases across a period due to increased nuclear charge.
- Ionization energy, the energy required to remove an electron, is inversely proportional to atomic radius.
- Electronegativity measures an atom's attraction for electrons; it increases left to right and decreases down a group.
Types of Elements
- Most of the periodic table is made up of metals, which are typically shiny, malleable, ductile, and good conductors.
- Nonmetals display opposite properties; they are dull, brittle, and poor conductors.
- Metalloids possess characteristics of both metals and nonmetals, acting as semiconductors.
Chemical Bonds and Ion Formation
- Atoms form ions through the gaining or losing of electrons, creating cations (positively charged) and anions (negatively charged).
- Metallic character refers to how easily an atom can lose electrons, correlating with reactivity in metals and nonmetals.
- The octet rule suggests that atoms strive for a full set of eight valence electrons for stability.
Quantum Mechanics and Electron Behavior
- Quantum numbers describe electron positions, including principal energy levels, orbital shapes, orientations, and spins.
- The Pauli Exclusion Principle allows a maximum of two electrons in an orbital with opposite spins, while Hund's Rule deals with the distribution of electrons among orbitals of the same energy.
- Atomic orbitals have distinctive shapes: s orbitals are spherical, and p orbitals are dumbbell-shaped.
Bonding Types
- Non-polar covalent bonds occur when electronegativity differences are less than 0.5, with electrons shared equally.
- Polar covalent bonds arise from electronegativity differences between 0.5 and 1.7, resulting in unequal sharing of electrons.
- Ionic bonds form when the electronegativity difference is greater than 1.7, typically between metals and nonmetals.
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Description
Explore the principles of electron configuration, including exceptions to the Aufbau principle, and the historical development of the periodic table. This quiz covers key figures and their contributions, such as Mendeleev and his predictions of undiscovered elements. Enhance your understanding of atomic structure and chemical properties.