Unit 1: Part 2 - Review Flashcards
What is the atomic radius trend?
increase down the group; decrease across the period
Why does the atomic radius increase down the group?
more energy levels are added, which increases the size of the atom
Why does the atomic radius decrease across the period?
as more electrons are added, the atom becomes “stronger,” which means the nucleus “hugs” the electrons closer and atom becomes more compact
What is ionization energy?
energy required to remove an electron from an atom
What is the trend for ionization energy?
decrease down the group; increase across the period
Why does ionization energy decrease down the group?
(related to atomic radius) as the atom gets bigger, electrons become easier to steal from as valence electrons are farther from the nucleus, so less IE is needed
Why does ionization energy increase across the period?
(related to atomic radius) as the atom gets more compact (smaller), the electrons on the outer shell become harder to steal as electrons are closer to the nucleus, so more IE needed
What is electron affinity?
the energy is given off when an electron is added to a neutral atom in the gas state
What is the trend for electron affinity?
decrease down the group; increase across the period
Why does electron affinity decrease down the group?
Decreasing down the group, the atom becomes less “negative” because the electrons that are far from the nucleus get repelled out farther by other electrons. The atoms do not want any more electrons as much.
Why does electron affinity increase across a period?
Increasing across the period, EA becomes more negative because the number of protons increase across the period, which creates a stronger attraction for electrons to the nucleus. So, electrons are held closer to the nucleus, negatively increasing EA.
What is electronegativity?
the ability of an atom in a compound to attract electrons
What is the trend for electronegativity?
decrease down the group; increase across the period
Why does electronegativity decrease down the group?
Down the group, there are more layers of electrons, so outer shell electrons are farther from the nucleus. Thus, the ability to attract electrons becomes harder as more energy levels are present.
Why does electronegativity increase across the period?
As the radius decreases, the electrons get closer to the nucleus. So, it is easier for the atom to attract electrons that will be closer to the nucleus.
What is shielding?
lower energy level electrons “shields” outer electrons from the pull of the nucleus
What is the trend for shielding?
increase down the group; constant across the period
Why does shielding increase down the group?
more energy levels are added down the group, so shielding increases
Why does shielding stay constant across the period?
no new energy levels are added across the period
What is ionic size?
the radius of an atom’s ion
