Keshu

Group 7- the halogens

fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).

The melting point of the halogens top to bottom decreases because as you move down, the atoms get larger and heavier, leading to stronger van der Waals force between the diatomic molecules, requiring more energy to melt or boil.

Van der Waals forces are weak, short-range electrostatic attractions between neutral atoms or molecules.

Electrostatic attraction is the force of attraction between two oppositely charged particles, like a positive and a negative charge.

The four fundamental forces are gravity, the electromagnetic force, the strong nuclear force, and the weak nuclear force.

The electromagnetic force is one of the four fundamental forces of nature, arising from the interaction between electrically charged particles.

A phenomenon is the formation of new substances from original ones due to chemical reactions

An irreversible process in chemistry is a chemical reaction or a physical change that cannot be reversed.

Group 8 - noble gases

In Group 8 (the noble gases), the melting point increases as you move down the group

As you move down the group, new electron shells are added, making the atoms larger.