Explanation:
Lithium is an electropositive element that readily loses electrons.
Oxygen is electronegative and it will readily accept electrons.
Due to this significant electronegativity differences between the two species they form electrovalent or ionic bonds between them.
2atoms of Li lose two electrons:
Li → Li²⁺ + e⁻
Lithium isoelectronic with helium
For oxygen;
O + 2e⁻ → O²⁻
Oxygen is isoelectronic with Neon
Two ions of the lithium combines with the oxygen to form the bond;
4Li + O₂ → 2Li₂O
The electrostatic attraction between the two ions forms the ionic bond
If the crucible wasn't covered with a lid the reactants may have produced a gas that was released into the surroundings, or mass may have been lost in the form of water vapour.
The third reason helped Rutherford to discover the nucleus.
A polymer is a really long chain of smaller molecules (monomers). It's similar to a chain of paper clips because all of the little monomers will attach to each other, forming a long strain.