Medicinal Chemistry: The Periodic Table

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Questions and Answers

What is the primary factor used to arrange the elements in the periodic table?

Atomic number (correct)

Chemical reactivity

Density of elements

Increasing atomic mass

Which of the following best defines 'effective nuclear charge'?

The total charge of an electron cloud

The amount of energy required to remove an electron

The net positive charge experienced by an electron in an atom (correct)

The sum of protons in the nucleus

How does the atomic radius generally change as you move down a group in the periodic table?

It increases (correct)

It remains constant

It decreases

It fluctuates randomly

Which group in the periodic table contains the alkali metals?

Group 1 Signup and view all the answers

What does electron affinity refer to?

The energy change when an electron is added to a neutral atom Signup and view all the answers

Which of the following is considered a metalloid?

Silicon Signup and view all the answers

What characteristic primarily differentiates transition metals from other groups?

They can form multiple oxidation states Signup and view all the answers

Which element is typically found in the halogen group?

Fluorine Signup and view all the answers

What defines an atom's electronegativity?

Its ability to attract electrons in a chemical bond Signup and view all the answers

Which of the following correctly explains why fluorine is the most electronegative element?

It possesses a high nuclear charge with little shielding Signup and view all the answers

How does the electronegativity trend change across a period in the periodic table?

It increases from left to right Signup and view all the answers

Which element has a higher electronegativity than carbon but lower than fluorine?

Oxygen Signup and view all the answers

What phenomenon occurs when fluorine competes with hydrogen for electrons in a bond?

Partial positive charge on hydrogen Signup and view all the answers

What effect does an increased distance between the nucleus and the outermost electron have on ionisation energy?

Ionisation energy decreases. Signup and view all the answers

Which group of elements is characterized by the lowest ionisation energy?

Alkali metals Signup and view all the answers

How is electron affinity defined?

The energy change when an electron is accepted by an atom. Signup and view all the answers

What does a more positive value of electron affinity indicate?

The atom has a high tendency to accept electrons. Signup and view all the answers

In a bond between two different atoms, how is electron sharing typically characterized?

Electrons are shared unequally. Signup and view all the answers

What happens to the ionic radius when a cation is formed?

It decreases due to less electron repulsion. Signup and view all the answers

Why is the radius of Mg2+ smaller than that of Na+?

Mg2+ has a higher nuclear charge, leading to stronger attraction. Signup and view all the answers

How does the ionic radius of Na+ compare to that of its neutral atom?

Na+ is smaller than the neutral Na atom. Signup and view all the answers

Which statement about isoelectronic ions is correct?

Isoelectronic ions have the same electron configuration. Signup and view all the answers

What characteristic of cations influences their size in comparison to anions?

Cations possess a higher effective nuclear charge. Signup and view all the answers

What is the ionic radius of Na+?

99 pm Signup and view all the answers

Which of the following ions is likely to exhibit the largest ionic radius?

Cl- Signup and view all the answers

What effect does a higher nuclear charge have on ionic size?

It decreases the ionic size by increasing attraction. Signup and view all the answers

What is the main factor that determines the attraction between valence electrons and the nucleus?

The number of protons in the nucleus Signup and view all the answers

Which property is characteristic of metals compared to nonmetals?

Good conductors of heat and electricity Signup and view all the answers

Which of the following groups contains the most reactive elements?

Halogens Signup and view all the answers

What does the effective nuclear charge (Zeff) take into account?

The actual nuclear charge and shielding from other electrons Signup and view all the answers

What role do valence electrons play in chemical reactions?

They participate in sharing and exchange during reactions Signup and view all the answers

What happens to the effective nuclear charge as the shielding effect increases?

It decreases Signup and view all the answers

Which element property tends to vary significantly across different groups in the periodic table?

Chemical properties Signup and view all the answers

Which statement correctly reflects the arrangement of the modern periodic table?

Organized by increasing atomic number Signup and view all the answers

How does the effective nuclear charge (Zeff) change as you move from left to right across a period?

Increases due to more protons in the nucleus while adding electrons to the same energy level. Signup and view all the answers

What happens to the atomic radius as you move down a group in the periodic table?

It increases due to the addition of energy levels. Signup and view all the answers

Why do valence electrons not shield each other well?

They occupy the same energy level and experience similar repulsive forces. Signup and view all the answers

What is the formula for calculating effective nuclear charge (Zeff)?

Zeff = Z - s Signup and view all the answers

What effect does increasing atomic number (Z) have on atomic radius across a period?

Decreases atomic radius due to greater attraction from the nucleus. Signup and view all the answers

What occurs to the ionic radius when a chlorine atom (Cl) forms an anion (Cl-)?

The ionic radius increases due to additional repulsive forces among electrons. Signup and view all the answers

According to Slater's rules, what does the calculation of σ account for?

Efficient shielding effects of inner-shell electrons. Signup and view all the answers

What primarily causes the increase in atomic radius when moving down a group?

More energy levels being added to accommodate additional electrons. Signup and view all the answers

Study Notes

Fundamentals of Medicinal and Pharmaceutical Chemistry: The Periodic Table

The periodic table arranges 118 elements
Elements are grouped into families
The table displays elements according to increasing atomic number

FUNCHEM 3 Learning Outcomes

Recognize the arrangement of elements in the periodic table by increasing atomic number
Differentiate between periods and groups of elements (metals, nonmetals, metalloids, alkali metals, alkaline earth metals, transition metals, halogens, inert gases, lanthanides, and actinides)
Define "effective nuclear charge"
Define "atomic radius", "ionic radius", "ionization energy", "electron affinity", and "electronegativity", and describe how each varies across a period and down a group
Understand and analyse data from the periodic table

Mendeleev's Periodic Table

Dmitri Mendeleev created the first periodic table in 1869
Organized elements by increasing atomic mass
Predicted the existence and properties of undiscovered elements based on gaps in the table
Mendeleev did not understand the internal structure of atoms

The Modern Periodic Table

Elements are arranged according to increasing atomic number
Elements within a group have similar chemical properties
Metals are good conductors of heat and electricity, while nonmetals are poor conductors
Elements have varying properties and behaviour. Similarities emerge within families

Valence Electrons

Valence electrons affect chemical reactions by participating in sharing or exchange
The attraction between the nucleus and valence electrons depends on: number of protons in the nucleus, shielding effect of other electrons, and distance from the nucleus.

Effective Nuclear Charge (Z_eff)

This is the nuclear charge an electron experiences after accounting for the shielding effect of other electrons
Z_eff increases moving left to right across a period due to increasing nuclear charge and fewer shielding electrons
Z_eff increases going down a group due to increased shielding and a greater number of electrons in inner shells.

Atomic Radius

Atomic radius is half the distance between the nuclei of two adjacent atoms.
Atomic radius decreases across a period, as effective nuclear charge increases and pulls the electron cloud closer to the nucleus
Atomic radius increases down a group, due to the addition of electron shells

Ionic Radius

Ionic radius affects chemical reactions and cellular processes.
Anion formation increases radius (additional electron → increased repulsion → size increases)
Cation formation decreases radius (lost electron → reduced repulsion → size decreases)
Isoelectronic ions (same number of electrons) with different charges and nuclear charge will affect ionic radius.

Ionisation Energy

Ionisation energy is the energy required to remove an electron from a gaseous atom
It increases across a period due to increasing effective nuclear charge
It decreases down a group due to increasing atomic size and shielding

Electron Affinity

Electron affinity is the energy change when an electron is accepted by a gaseous atom.
More positive electron affinity indicates a greater tendency to accept an electron (becomes negative when energy is released).
Electron affinity trends vary across periods and groups.

Electronegativity

Electronegativity is the ability of an atom to attract shared electrons in a bond.
It increases across a period and decreases down a group due to variation in shielding and effective nuclear charge.
Fluorine is the most electronegative element. It has high electron affinity and ionization energy.

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Description

Explore the fundamentals of the periodic table in medicinal and pharmaceutical chemistry. This quiz focuses on the arrangement of elements, including periods and groups, and key concepts like atomic radius and ionization energy. Enhance your understanding of how these properties vary across the table.