4A2 Trends and Patterns of the Periodic Table Flashcards
Predict trends in atomic radius, ionization energy, electronegativity, and reactivity based on periodic table position.
Define:
atomic radius
The size of a neutral atom, measured from the nucleus to the outermost electron.
Atomic radius increases down a group due to additional orbitals and decreases across a period due to stronger nuclear pull.
Define:
ionic radius
The radius of an ion, which changes when an atom gains or loses electrons to form an ion.
Gaining electrons increases ionic radius (anion), while losing electrons decreases it (cation).
True or False:
Ionic radius is the same as atomic radius.
False
Ionic radius changes based on electron gain/loss, while atomic radius pertains to neutral atoms.
Why does ionic radius increase down a group?
Because the number of electron orbitals increases, resulting in a larger ion size.
Moving down a group means entering higher periods with additional electron shells.
Which has a smaller atomic radius:
sodium (Na) or chlorine (Cl)
Chlorine (Cl)
Chlorine has more protons, pulling electrons closer and decreasing its radius.
How does ionic radius differ between cations and anions?
Cations have smaller ionic radii, while anions have larger ionic radii compared to their atoms.
This is due to the loss of electrons in cations and the gain of electrons in anions.
Extra electrons in anions repel each other, expanding the electron cloud.
Why does atomic radius decrease across a period?
Because the number of protons increases, pulling electrons closer to the nucleus.
This stronger nuclear pull reduces the size of the electron cloud.
List two factors affecting the ionic radius.
- Electron gain or loss.
- Spin and coordination number.
More surrounding bonds or higher spin increases ionic radius.
How does the number of protons affect ionic radius in isoelectronic ions?
More protons result in a smaller ionic radius.
Protons pull electrons closer, reducing the size of the ion.
True or False:
Fluorine (F⁻) has a larger ionic radius than Oxygen (O²⁻).
False
Oxygen has fewer protons than fluorine, so it exerts less pull on its electrons, leading to a larger ionic radius.
What is the relationship between atomic radius and electronegativity?
Atoms with smaller atomic radii tend to have higher electronegativity.
A tighter hold on electrons leads to a greater ability to attract electrons in a bond.
Why does fluorine (F) have a smaller atomic radius than lithium (Li)?
It has more protons, pulling electrons closer to the nucleus.
The increased nuclear charge reduces the size of the electron cloud.
Define:
diagonal relationship on the periodic table
It is the similarities in properties between certain pairs of diagonally adjacent elements in the second and third periods of the periodic table.
It is caused by similar ionic potentials and opposing trends in atomic properties across periods and down groups.
For example, atomic radii increase down a group but decrease across a period, creating similarities diagonally.
List five element pairs that exhibit diagonal relationships.
- Lithium-Magnesium
- Beryllium-Aluminum
- Boron-Silicon
- Carbon-Phosphorus
- Nitrogen-Sulfur
These pairs share properties such as:
- Atomic radii
- Amphoteric behavior
- Covalent character
- Electronegativity
List three properties shared by Beryllium and Aluminum.
- Amphoteric oxides and hydroxides.
- Covalent bonding tendencies.
- Solubility in organic solvents.
Beryllium and Aluminum form compounds with low melting points and exhibit amphoteric behavior.
Define:
amphoteric behavior
A substance’s ability to act as both an acid and a base.
Beryllium and Aluminum oxides exhibit this property.
Define:
metallic character
It is an element’s tendency to lose electrons and exhibit properties like malleability and electrical conductivity.
Metallic character depends on atomic radii and ionization energy.
How does atomic radius trend affect metallic character?
As atomic radius increases, metallic character increases.
Larger atomic radii reduce the nuclear pull on valence electrons, making it easier to lose electrons.
How does metallic character vary across a period?
It decreases from left to right.
As you move across a period, atomic radii decrease, and ionization energy increases, making it harder for elements to lose electrons.
Fill in the blank:
Metallic character increases when moving _____ a group.
down
As you move down a group, atomic radii increase, and ionization energy decreases, making it easier for elements to lose electrons.
True or False:
Boron and Silicon are semiconductors.
True
Both Boron and Silicon are nonmetals, semiconductors, and exhibit allotropy.
Allotropy refers to the ability of an element to exist in different physical forms.
Which elements form triple bonds and exhibit allotropy?
Carbon and phosphorus
Both elements show strong sigma and pi bonding and exist in different forms.
How does boiling point trend across a period?
It increases from left to the middle of a period and decreases sharply in the nonmetals.
Metals have stronger bonds, leading to higher boiling points, while nonmetals have weaker intermolecular forces.
Fill in the blank:
Nitrogen and Sulfur both exhibit _______.
diamagnetism
Diamagnetism is a property where substances are weakly repelled by a magnetic field.
Define:
electronegativity
The ability of an atom to attract and hold electrons in a chemical bond.
Electronegativity is measured using the Pauling scale and varies across elements in the periodic table.
How does electronegativity change down a group?
It decreases.
Due to the increase in the number of electron shells, which increases nuclear shielding.
True or False:
Electronegativity decreases across a period in the periodic table.
False
Electronegativity increases across a period due to the increase in nuclear charge and a decrease in atomic radius.
Which element has a lower electronegativity:
potassium or phosphorus
potassium
Electronegativity decreases down a group and increases across a period; potassium is farther left than phosphorus.
Why does fluorine have a high electronegativity?
- Its small atomic radius.
- Its high nuclear charge.
Fluorine’s strong pull on electrons is due to minimal shielding and a high proton count.
It has the highest electronegativity of any element with a value of 3.98 on the Pauling scale.
Define:
nuclear shielding
The reduction in effective nuclear charge on outer electrons due to inner electron shells.
Greater shielding reduces electronegativity by lessening the nucleus’s pull on outer electrons.
Fill in the blank:
The least electronegative element is _______.
Francium
Francium has an electronegativity value close to 0, indicating its inability to hold electrons tightly.
True or False:
Noble gases typically have electronegativity values greater than 0.
False
Most noble gases have a value of 0 due to their full electron shells, which do not require attracting more electrons.
How does the number of electron shells affect electronegativity?
More shells reduce electronegativity due to increased shielding.
The greater the number of electron shells, the weaker the attraction between the nucleus and the outermost electrons.
Fill in the blank:
Electronegativity increases across a period due to increasing ______ ______.
nuclear charge
A higher number of protons increases the pull on bonding electrons.
Which element has a greater electronegativity:
sulfur or oxygen
oxygen
Oxygen is farther to the right on the periodic table, and electronegativity increases across a period.
Define:
ionization energy
The minimum energy required to remove the outermost electron from a gaseous atom of an element.
Ionization energy is measured in kilojoules per mole and is influenced by atomic structure.
List three factors affecting ionization energy.
- Number of protons
- Number of electron shells
- Number of electrons
These factors influence how strongly the nucleus attracts the outermost electrons.
How does the number of protons affect ionization energy?
More protons increase ionization energy by creating a stronger positive charge that attracts electrons.
A higher proton count in the nucleus increases the hold on electrons.
What is the relationship between ionization energy and atomic radius?
Ionization energy decreases as atomic radius increases.
A larger radius places electrons farther from the nucleus, reducing nuclear attraction.
How does the number of electron shells affect ionization energy?
More electron shells decrease ionization energy because outer electrons are farther from the nucleus.
Additional electron shells weaken the nucleus’s hold on valence electrons.
Fill in the blank:
Ionization energy _______ across a period from left to right.
increases
This is due to an increase in the number of protons.
True or False:
Ionization energy decreases as you move down a group.
True
Due to an increase in the number of electron shells.
What happens to ionization energy as atomic radius increases?
It decreases.
A larger atomic radius increases the distance between the nucleus and valence electrons, weakening the attraction.
Why does cesium have lower ionization energy than lithium?
Cesium has more electron shells, increasing the distance between the nucleus and its valence electrons.
The outermost electrons in cesium experience less nuclear attraction than in lithium.
Which element has higher ionization energy:
fluorine or lithium
fluorine
Fluorine has more protons, resulting in a stronger nuclear pull on its electrons.
Define:
second ionization energy
The energy required to remove an electron from a singly charged gaseous cation.
It is always greater than the first ionization energy due to increased nuclear attraction.
True or False:
Nonmetals have low ionization energy.
False
Nonmetals have high ionization energy, meaning they strongly attract electrons and do not lose them easily.
Fill in the blank:
The more _______ an ion becomes, the harder it is to remove additional electrons.
positive
The increasing positive charge strengthens the hold on remaining electrons, raising ionization energy.
