Answer:
The answer to your question is below:
Explanation:
1.- Atomic number, elements in the periodic table increase their atomic number from left to right.
2.- A weighted average of the masses of an element's isotopes.
3.- Most metals are brittle, Metals are not brittle, Non metals are brittle.
4.- Most reactive nonmetals, that is because halogens have 7 valence electrons that means that only need one electron to be stable.
5.- Amu, is the abbreviation of Atomic mass unit.
