Question

5
identify the correct trend going down groups 1 and 17. * (0.5 points)
electronegativity decreases
melting points increase
atomic radius decreases
ionisation energy increases

Explanation:

• Electronegativity: Electronegativity decreases down both Group 1 (alkali metals) and Group 17 (halogens). This is because as you go down a group, the atomic radius increases, and the outermost electrons are further from the nucleus, so the nucleus has less attraction for bonding electrons.
• Melting points: In Group 1 (metallic bonding), melting points decrease down the group as the metallic bonds weaken (larger atoms, more diffuse electron - cloud). In Group 17 (molecular - covalent, with London dispersion forces), melting points increase down the group as the molar mass of the diatomic molecules (\(F_2\), \(Cl_2\), \(Br_2\), \(I_2\)) increases, leading to stronger London dispersion forces. So, the melting - point trend is not the same for both groups.
• Atomic radius: Atomic radius increases down both groups. As you go down a group, there are more electron shells.
• Ionisation energy: Ionisation energy decreases down both groups. Larger atoms (more electron shells) mean that the outermost electrons are more shielded from the nuclear charge and easier to remove.

Answer:

electronegativity decreases