Atomic Radius
The element in period 5 with the largest atomic radius.
Rubidium (Rb)
Explanation: Rubidium is in group 1, it has the weakest effective nuclear charge of the elements in period 5.
The energy required to remove a second electron, after one has already been removed.
What is second ionization energy?
Explanation: ionization energy is the energy to remove an electron, if one has already been previously removed, we are now looking at the second ionization energy aka the energy to remove a second electron.
The most electronegative element
What is Fluorine?
Explanation: Fluorine has the greatest effective nuclear charge.
The group that have the highest electron affinities
What are the halogens/group 17?
Explanation: halogens have high electron affinities, because they have nearly full valence shells, and smaller atomic radii than other elements in the same period. This helps gives them a stronger effective nuclear charge and thereby a stronger electron affinity.
The ion with the smaller ionic radius:
S2- or K+
What is Potassium ion (K+)?
Explanation: cations have smaller ionic radii than anions in an isoelectronic species, because of the lower amount of repulsion
The element in the pair with the larger atomic radius:
Li or K
What is Potassium (K)?
Explanation: Potassium is located in period 4, below Lithium is in period 2. Potassium has 4 shells, while Lithium has 2.
The element in the pair with the higher first Ionization energy:
N or Si
What is Nitrogen (N)?
Explanation: Nitrogen is both above and to the right of Silicon. Ionization energy increases up and to the right on the table.
The more electronegative of the 2 elements:
O or C
What is oxygen (O)?
Explanation: Both are period 2 elements, but Oxygen is closer to the right and has a stronger pull on electrons, because the attractive forces from the nucleus are stronger than in Carbon. (greater effective nuclear charge)
The element with the greater electron affinity: S or O.
What is Sulfur?
Explanation: Although oxygen should have a higher EA as predicted by periodic trends, the small size of oxygen creates for strong repulsive forces between close together electrons, making a gain of an electron less energetically favourable.
The least electronegative halogen.
*Only consider periods 1-5*
What is Iodine?
Explanation: Iodine is located the furthest down of all the halogens, it has the largest atomic radius and thereby the weakest pull on its valence shell electrons.
The element of the 3 with the smallest atomic radius:
Cl-, Na+, or K
What is Sodium (Na+)?
Explanation: The Sodium cation is isoelectronic with Neon (Ne) while Chlorine is isoelectronic with Argon. Further, K is larger than Na because it has the weaker effective nuclear charge since they're in same group but K is in period 4 and if Na < K and Na+ < Na then Na+ < K.
The group with the largest first ionization energies.
What are the noble gases?
Explanation: Noble gases are at the most stable conformation with full valence shells, removal of an electron disrupts the stable state and makes the gas much less stable which is why it requires the most energy.
4.0
What is the electronegativity of Fluorine? OR: What is the highest possible value of electronegativity?
Explanation: electronegativity values range up to 4.
This group have lower electron affinities than predicted by the trend for electron affinity.
What are group 15 elements?
Explanation: group 15 elements have unpaired electrons in their outermost p orbital, so the addition of an electron requires electron pairing, which is less favoured than expected, because of repulsive forces between electrons.
Shielding is constant because addition of electron is cancelled by the addition of a proton.
Why is the atomic radius of D block elements in the same period similar? What are the D block elements (in the same period/row)?
Explanation: the D block elements in the same row have similar atomic radii because the addition of an electron to the inner 3d orbital is cancelled by the addition of a proton so shielding is similar.
The element in the p block with the largest atomic radius.
What is Nh (Nihonium)?
Explanation: Nh is in group 13, the leftmost of the 6 groups in the p orbital giving it the weakest effective nuclear charge in its row, and is in period 7, so it has the most shells possible.
Paired electrons in a 2p orbital repel, but upon removal of one of the paired electrons, repulsive forces are lost and a more stable configuration is achieved.
Why is the first ionization energy of Oxygen lower than that of Nitrogen?
Explanation: Neutral oxygen atoms have 4 electrons in their p orbitals, which forces 2 electrons to pair up. These paired electrons repel each other. When one electron is removed, each p orbital is now occupied by only one electron and repulsive forces are much lower resulting in a much more stable state while removing an electron from Nitrogen is less favourable since it disrupts "semistable" conformation (2p3 vs. 2p4 or 2p2).
Electronegativity difference of 0.0 - 0.4.
What is a nonpolar covalent bond?
Explanation: difference in electronegativities is used to calculate bond polarity. A small difference (0.0-0.4) is a non polar bond. This means the electrons are shared equally/close to equally.
the element with the highest electron affinity.
What is Chlorine?
Explanation: although the trend predicts it to be Fluorine, the small size of the Fluorine atom causes a lot of repulsion between close together electrons, making gaining of an electron slightly less favourable than in chlorine
This trend increases at two corners of the periodic table.
What is reactivity?
Explanation: reactivity is highest in the top right corner where reactive halogens are, and bottom left corner, where reactive alkali metals are.
The smallest atom.
What is Helium?
Explanation: Helium and Hydrogen are the 2 smallest atoms. Helium is smaller, because it has a stronger effective nuclear charge, since there are no core electrons, there is minimal shielding, but there are more protons.
This p block element has a lower IE than its s block neighbour.
What is Boron?
Explanation: Boron has one electron in its 2p orbital, so the losing the 1 electron requires little energy, because than it has "complete shell", since p orbitals are now empty.
Least electronegative atom in a compound
What is the central atom in a Lewis structure?
Explanation: The least electronegative atom is usually the central atom unless it is Hydrogen. This atom usually has the highest capacity to form bonds/can form the most bonds.
Electron repulsive forces are lower because electrons are further apart in larger atoms.
Why does electron affinity not decrease down every group?
Explanation: In larger atoms the electrons are more spread out, so there is less repulsion + some orbitals contain electrons that do not shield as well, meaning stronger effective nuclear charge, therefore more favourable electron gain.
These noble gases react with Fluorine under extreme conditions.
What are Xenon and Krypton?
Explanation: Xenon and Krypton can react with Fluorine under extremely harsh conditions.
Kr + F2 -> KrF2
Xe + F2 -> XeF2
Xe + 2F2 -> XeF4
Xe + 3F2 -> XeF6