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What happens to the effective nuclear charge as you move across a period?
What happens to the effective nuclear charge as you move across a period?
Which of the following correctly describes the trend of effective nuclear charge down a group?
Which of the following correctly describes the trend of effective nuclear charge down a group?
According to Slater's Rules, how much nuclear charge do valence electrons in the same group shield?
According to Slater's Rules, how much nuclear charge do valence electrons in the same group shield?
What should be ignored when calculating the effective nuclear charge for an electron of interest?
What should be ignored when calculating the effective nuclear charge for an electron of interest?
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In Slater's Rules, how much nuclear charge do electrons in the (n-1) group shield for an ns or np valence electron?
In Slater's Rules, how much nuclear charge do electrons in the (n-1) group shield for an ns or np valence electron?
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What is the shielding constant (S) when calculating the effective nuclear charge for an electron in the (ns, np) group with 6 other electrons present in the same group?
What is the shielding constant (S) when calculating the effective nuclear charge for an electron in the (ns, np) group with 6 other electrons present in the same group?
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For an electron in the (nd) group, which electrons contribute to the shielding effect?
For an electron in the (nd) group, which electrons contribute to the shielding effect?
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What is the correct formula for calculating the effective nuclear charge (Z*)?
What is the correct formula for calculating the effective nuclear charge (Z*)?
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What is the value of shielding constant (S) for the (nf) group when there are no other electrons present?
What is the value of shielding constant (S) for the (nf) group when there are no other electrons present?
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Calculate the effective nuclear charge for the last electron in an atom with an atomic number (Z) of 17, given a shielding value (S) of 10.9.
Calculate the effective nuclear charge for the last electron in an atom with an atomic number (Z) of 17, given a shielding value (S) of 10.9.
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In the calculation of effective nuclear charge, which set of electrons does NOT contribute to shielding when considering a 3d electron?
In the calculation of effective nuclear charge, which set of electrons does NOT contribute to shielding when considering a 3d electron?
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For the last electron in the electron configuration of Bromine, what is the effective nuclear charge calculated using the configuration (1s)2 (2s, 2p)8 (3s, 3p)8 (3d)10 (4s, 4p)7?
For the last electron in the electron configuration of Bromine, what is the effective nuclear charge calculated using the configuration (1s)2 (2s, 2p)8 (3s, 3p)8 (3d)10 (4s, 4p)7?
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The effective nuclear charge (Z*) for an electron in an atom is significantly influenced by which of the following factors?
The effective nuclear charge (Z*) for an electron in an atom is significantly influenced by which of the following factors?
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How do stable electronic configurations affect electron affinity?
How do stable electronic configurations affect electron affinity?
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What trend occurs in electron affinity as you move from left to right across a period in the periodic table?
What trend occurs in electron affinity as you move from left to right across a period in the periodic table?
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Which statement correctly describes the trend in electron affinity down a group?
Which statement correctly describes the trend in electron affinity down a group?
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Why does the second electron affinity (EA2) typically have a positive value?
Why does the second electron affinity (EA2) typically have a positive value?
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Which element has a higher electron affinity between fluorine (F) and chlorine (Cl)?
Which element has a higher electron affinity between fluorine (F) and chlorine (Cl)?
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Which element has very low electron affinity due to its electronic configuration?
Which element has very low electron affinity due to its electronic configuration?
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What is the overall effect of electron proximity on electron affinity?
What is the overall effect of electron proximity on electron affinity?
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What causes beryllium (Be) and magnesium (Mg) to have very low electron affinities?
What causes beryllium (Be) and magnesium (Mg) to have very low electron affinities?
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What defines the reason for inert gases having zero electron affinity?
What defines the reason for inert gases having zero electron affinity?
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How does electronegativity change as you move from left to right across a period?
How does electronegativity change as you move from left to right across a period?
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Which element has the highest electronegativity value on the Pauling scale?
Which element has the highest electronegativity value on the Pauling scale?
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What happens to the electronegativity as you move down a group in the periodic table?
What happens to the electronegativity as you move down a group in the periodic table?
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What is meant by polarization in chemical bonding?
What is meant by polarization in chemical bonding?
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What does Fajans' Rule help predict?
What does Fajans' Rule help predict?
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What is the relationship between electronegativity and partial charges in a molecule like HCl?
What is the relationship between electronegativity and partial charges in a molecule like HCl?
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What does polarizability refer to in a chemical bond?
What does polarizability refer to in a chemical bond?
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What is the primary feature distinguishing groups in the modern periodic table?
What is the primary feature distinguishing groups in the modern periodic table?
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Which period of the modern periodic table contains the element Ne?
Which period of the modern periodic table contains the element Ne?
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How many groups are there in the modern periodic table?
How many groups are there in the modern periodic table?
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Which of the following elements is found in the fourth period?
Which of the following elements is found in the fourth period?
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What is the characteristic of the first period in the modern periodic table?
What is the characteristic of the first period in the modern periodic table?
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Which elements occupy the sixth period of the modern periodic table?
Which elements occupy the sixth period of the modern periodic table?
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The transition elements in the periodic table belong to which groups?
The transition elements in the periodic table belong to which groups?
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In the modern periodic table, how is the atomic number related to element properties?
In the modern periodic table, how is the atomic number related to element properties?
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Study Notes
Modern Periodic Table
- The physical and chemical properties of elements are periodic functions of their atomic numbers.
- Elements with similar properties are arranged in vertical columns known as groups.
- Horizontal rows in the periodic table are known as periods.
- The Modern Periodic Table consists of 7 periods and 18 groups.
- Each period is characterized by its principal quantum number (n).
- The first period has two elements: Hydrogen (H) and Helium (He) — filling the 1s orbital.
- The second period contains eight elements: Lithium (Li) to Neon (Ne) — filling the 2s and 2p orbitals.
- The third period consists of eight elements: Sodium (Na) to Argon (Ar) — filling the 3s and 3p orbitals.
- The fourth period has 18 elements: Potassium (K) to Krypton (Kr) — filling the 4s, 4p, and 3d orbitals, containing 10 transition elements (Scandium (Sc) to Zinc (Zn)).
- The fifth period contains 18 elements: Rubidium (Rb) to Xenon (Xe) — filling the 5s, 5p, and 4d orbitals, containing 10 transition elements (Yttrium (Y) to Cadmium (Cd)).
- The sixth period has 32 elements: Cesium (Cs) to Radon (Rn) — filling the 6s, 5d, 6p, and 4f orbitals, containing 14 lanthanides (Lanthanum (La) to Lutetium (Lu)).
Effective Nuclear Charge (Z*)
- Effective nuclear charge increases across a period due to increasing nuclear charge with minimal shielding effect.
- Effective nuclear charge decreases down a group because the shielding effect outweighs the increasing nuclear charge.
- Slater's Rules are used to calculate effective nuclear charge:
- Ignore electrons in higher groups (those to the right in the electronic configuration).
- For ns and np electrons:
- Electrons in the same group shield 0.35 (except for 1s, shielded by 0.30).
- Electrons in the (n-1) group shield 0.85.
- Electrons in the (n-2) or lower groups shield 1.00.
- For nd and nf electrons:
- Electrons in the same group shield 0.35.
- Electrons in lower groups shield 1.00.
Ionization Energy
- Ionization energy (IE) is the energy needed to remove one electron from a gaseous atom in its ground state.
- First ionization energy refers to the removal of the first electron, second ionization energy refers to the removal of the second electron, and so on.
- General trends:
- IE increases across a period due to the increasing nuclear charge and decreasing atomic size.
- IE decreases down a group because of the increasing atomic size and shielding effect.
- Exceptions:
- IE of Group 13 and Group 15 elements is lower than the preceding element due to the half-filled and completely filled valence shells in the preceding elements.
- Important note: IE has units of kJ/mol.
Electron Affinity (EA)
- Electron affinity is the energy change when an electron is added to a gaseous atom in its ground state.
- It can be positive or negative.
- Negative EA indicates energy is released during the addition of an electron, making the process exothermic.
- Positive EA indicates energy is absorbed during the addition of an electron, making the process endothermic.
- General trends:
- EA becomes more negative (more exothermic) across a period, as the added electrons are closer to the nucleus and experience a stronger attraction.
- EA becomes less negative (more endothermic) down a group because the added electrons are further from the nucleus and experience weaker attraction.
- Exceptions:
- EA of Group 18 (Noble gases) is almost zero because their valence shells are completely filled, making them stable.
- EA of Group 14 (Carbon group) is less negative due to the half-filled p orbitals.
Electronegativity
- Electronegativity (EN) is a measure of an atom's tendency to attract electrons in a covalent bond.
- It is a dimensionless quantity.
- General trends:
- EN increases across a period due to the increasing nuclear charge and decreasing atomic size.
- EN decreases down a group due to the increasing atomic size and shielding effect.
- Linus Pauling's scale is a widely used scale for electronegativity, with fluorine being the most electronegative element (EN = 4.0) and cesium being the least electronegative (EN = 0.8).
Polarization
- Polarization occurs due to the difference in electronegativity between cations and anions in an ionic compound.
- The electron density of the cation is attracted towards the more electronegative anion, resulting in a deformation of the anion.
- The tendency of the anion to get deformed is called polarizability.
- The ability of a cation to deform an anion is called the polarizing power.
Fajans' Rules
- Fajans' Rules predict the degree of covalent character in an ionic compound based on the cation's size and charge.
- Smaller cations with higher charges have greater polarizing power, leading to a higher degree of covalent character in the compound.
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Description
Explore the structure and significance of the Modern Periodic Table in this quiz. Learn about the arrangement of elements in groups and periods, their atomic numbers, and how they relate to physical and chemical properties. Perfect for anyone studying chemistry or looking to refresh their knowledge on this fundamental topic.
