Chlorine and bromine have very similar chemical properties. This is best explained by the fact that both elements:

Outermost (valence) electrons

Ahigh energy (high speed) particle (alpha or beta or neutron) are shot at the target;

Polyethylene is a strong synthetic polymer that can be used to make toys and bottles. this makes plastics which are important also to people but sometimes it lead to harmful environmental effects such as global warming if these plastics are burned.