Atomic Anatomy
As you move from top to bottom down a group on the periodic table, this primary structural feature increases with each new row.
What are energy levels (or electron shells)?
This is the minimum amount of energy required to completely remove an electron from a gaseous atom or ion.
What is ionization energy?
Holding the title of the most electronegative element on the periodic table, it is assigned a maximum value of 4.0 on the Pauling scale.
What is Fluorine?
These highly reactive Group 1 metals are soft enough to cut with a knife and react violently when dropped into water.
What are the alkali metals?
Despite being a gas and a nonmetal, this element is placed at the top of Group 1 because it possesses exactly one valence electron.
What is Hydrogen?
This is the general trend for atomic radius as you move from left to right across a single period.
What is decreasing?
This group of elements boasts the highest first ionization energies in their respective periods due to their completely filled valence shells.
What are the noble gases?
Unlike electronegativity, which involves bonding, this related periodic property measures the energy change that occurs when a neutral gaseous atom gains an electron.
What is electron affinity?
These elements span groups 3 through 12 and are famous for forming brightly colored compounds and having partially filled d subshells.
What are the transition metals?
While melting points of metals generally decrease down a group, the melting points of this group of nonmetals increase down the group due to stronger London dispersion forces.
What are the Halogens?
This specific term describes the actual nuclear charge experienced by an electron in a multi-electron atom, which explains why atoms get smaller across a period.
What is effective nuclear charge?
While ionization energy generally increases across Period 2, it unexpectedly drops when moving from Nitrogen to this neighboring element because electron-electron pairing causes repulsion in the p-orbital.
What is Oxygen?
This group of elements has an electron affinity value of effectively zero (or positive/endothermic) because adding an electron forces it into a brand-new, higher energy subshell.
What are the Alkaline Earth Metals (Group 2) or Noble Gases (Group 18)?
As you move down the Halogen group (Group 17), this is the general trend for their chemical reactivity.
What is decreasing reactivity?
This term describes the diagonal relationship where Lithium shares more chemical similarities with Magnesium than it does with its own group members.
What is a diagonal relationship?
Even though it sits below fluorine, this element actually has a smaller atomic radius than you might expect because of the poor shielding of its $d$-block electrons.
What is Gallium?
For a Magnesium atom (1s^2 2s^2 2p^6 3s^2), you will see a massive, multi-thousand-volt spike when trying to remove this specific numbered electron.
What is the 3rd electron?
Although Fluorine is the most electronegative element, this element actually releases the most energy when gaining a single electron, giving it the highest electron affinity.
What is Chlorine?
This is the specific name given to the f-block elements found in row 6, prized for their magnetic and phosphorescent properties in modern tech.
What are the Lanthanides?
Beryllium has a higher first ionization energy than Boron. This is the structural reason for this break in the periodic trend.
What is a full 2s subshell?
Arrange these three isoelectronic species in order of increasing ionic radius: P^3-, S^2-, Cl^-.
Cl^- < S^2- < P^3-
This element has the highest first ionization energy of any element on the entire periodic table.
What is Helium?
This effect, caused by inner electrons blocking the outer valence electrons from the full pull of the nucleus, explains why electronegativity decreases down a group.
What is the shielding effect?
While metallic character increases down a group, this specific metalloid in Group 15 is the only element in its family that behaves almost strictly as a semiconductor, splitting the true metals from the nonmetals above it.
What is Arsenic (or Antimony)?
This relativistic effect causes heavy row 6 elements like Gold and Mercury to have distorted periodic properties (like Mercury being a liquid) because their inner s electrons travel near the speed of light.
What is the relativistic contraction (or the inert pair effect)?