Periodic Table Trends (Lessons 7 & 8) Flashcards
What are periodic table trends?
properties of elements that change across a period and down a group
What are the main periodic trends?
- atomic radius
- ionization energy (IE)
- electron affinity
- electronegativity
What is atomic size or radius?
-the distance from the centre of an atom (nucleus) to the outer boundary of electron cloud
What is the atomic radius trend?
Top to Bottom : increasing size
Left to Right: decreasing size
How does the shielding effect work?
As the inner shells get filled, the shells start to repel eachother which makes it harder to for the nuclear attraction from the nucleus to reach the outer valence electrons so they’re not as tightly held
What is effective nuclear charge?
it is the net force of nuclear attraction as experienced by the valence electrons after the shielding effect
Top to Bottom: Decreases
Left to Right: Increases
(Trend is opposite atomic radius trend)
What is ionization energy?
the minimum amount of energy to remove the most loosest held electron from an atom/ion at its gaseous ground state
What is the ionization trend?
Top to Bottom: Decreases
Left to Right: Increases
Why do atoms have to be in a ground, gaseous state when concerning IE and EA?
Ground state: where the electron should be
Gaseous state: so there is no attraction between electrons of neighbouring nuclei so the only attraction is of its own nucleus
What is the correlation between nuclear charge, effective nuclear charge, and IE magnitude?
nuclear charge increases, effective nuclear charge decreases, IE magnitude decreases
Nuclear charge decreases, effective nuclear charge increases, IE magnitude increases
What is electron affinity?
- the change in energy of an atom at its gaseous ground state when an electron is added to it
- the neutrals atom’s likelihood of graining an electron
What is the electron affinity trend?
Top to Bottom: [decreases] more endothermic (less favourable for nucleus to attract electrons bc increase inner shielding)
Left to Right: [increases] more exothermic (more favourable for nucleus to attract electrons bc more protons)
What is electronegativity?
- the measure of the ability of an atom to attract shared electrons
- based on many properties like IE and EA
What is the electronegativity trends?
Top to Bottom: Decreases
Left to Right: Increases
What is the electronegativity trend exception?
noble gases [these atoms have a full valence shell already so its less favourable (endothermic) to attract shared electrons]
