Group 7 (17), the halogens Flashcards
(13 cards)
What type of elements make up Group 7 of the Periodic Table?
Group 7 elements are non - metals known as the halogens
In what form do Group 7 elements exist naturally?
Halogens exist as diatomic molecules, such as F2, Cl2, Br2 and I2
What trend is observed in the appearance of the halogens going down Group 7?
The halogens get darker in colour and denser as you go down the group
Why are the properties of fluorine untypical compared to the other halogens?
Fluorine has an unusually weak F-F bond due to repulsion between non - bonding electrons, which are very close together because of fluorine’s small atomic size
What causes the F-F bond to be weaker than expected?
The small size of fluorine atoms leads to repulsion between lone pairs of electrons, weakening the bond
How does atomic size change going down Group 7?
The atoms get bigger going down the group because each element has one extra filled main level of electrons
What is electronegativity?
Electronegativity is a measure of the ability of an atom to attract electrons (electron density) towards itself within a covalent bond
What factors affect electronegativity?
Electronegativity depends on the nuclear charge, the distance between the nucleus and bonding electrons and the shieling effect from inner electron shells
Why does electronegativity decrease going down Group 7?
As atoms get larger, the paired electrons are further from the nucleus and experience more shielding, reducing the attraction between the nucleus and paired electrons, despite the increasing nuclear charge
How does the bonding in hydrogen halides illustrate the trend in electronegativity?
In hydrogen halides, the shared electrons in the H-X bond are further from the halogen nucleus going down the group, showing increased shielding and reduced electronegativity
How do melting and boiling points change going down Group 7?
Melting and boiling points increase down the group because larger atoms have more electrons, leading to stronger van der Waals forces between molecules
What is the relationship between the volatility and boiling point in Group 7 elements?
The lower the boiling point, the more volatile the element
What is the trends in ionisation energies as you go down group 7?
As you go down group 7, ionisation energy decreases.
This is because the atoms get bigger so they have more shielding.
Leading to weaker attractions between the nucleus and electrons in the outer shells
