Topic 3 & 13 Periodicity Flashcards
explain the trend in melting point down group 17
the melting point down group 17 increases because the molecules increase in size as there are more electrons and an increasing atomic radius. This results in stronger intermolecular forces between the atoms because of the increased likelihood of temporary dipoles forming (increasing the dispersion forces). More energy is therefore required to break apart the bonds between the atoms going down the group.
Explain the trend in ionization energy down group 17
Ionization energy decreases because there is a weaker force of electrostatic attraction. There is additional inner electron shielding on the outer electron shell and a larger atomic radius meaning the outer shell electrons are further away from the nucleus and there is a weaker force of attraction on them by the nucleus.
why is F- ion bigger than a F atom
F- ion is bigger than an F atom because there is an additional electron in the outer shell, resulting in more repulsion between the electrons in the same shell.
Which halogen is the strongest oxidizing agent
Fluorine, because it is the most reactive and has the least number of e- shells, meaning there is less e- shielding on the outer electrons and an increased electrostatic attraction. In addition, the electron shells are able to be pulled closer to the nucleus, so fluorine is more likely to remove an electron from another atom.
why does reactivity decrease down group 17
The atomic radius is smaller, so the electrons are not pulled in as closely to the nucleus, resulting in weaker attractive forces on the electrons in the outer shell, making it easier to grab e-.
Why can chlorine replace bromine in a displacement reaction
It is a better oxidizing agent and is more reactive -> there is a stronger force of electrostatic attraction between the nucleus and outer shell e- -> it takes the e- from bromine giving it a negative charge so it bonds with the positive potassium, Br is left with 7e- in its outer shell and forms Br2
physical properties of group 17
become darker down the group
diatomic
mp/bp increases bc larger molecules = stronger IMF
insulators of heat and electricity
What are group 1 metals often stored in
oils because the metals react readily with oxygen and water vapor in the air to form a layer of oxide
Physical properties of group 1 elements
high thermal and electrical conductivity
ductile
malleable
soft and silver metals
low melting points (explains why it is so soft)
Why do group 1 elements have low bp/mp
Group 1 elements only have 1 e- in their outershell, which is weakly attracted by the nucleus, causing the e- to drift further than in atoms of other elements in the same period. The larger atomic radii results in weaker forces between atoms and lower mp/bp
why does reactivity increase down group 1
The reactivity increases because the valence e- get further and further from the nucleus and can be pulled away easier.
