Magnesium and calcium have similar chemical properties because their atoms in the ground state have 1.
equal numbers of protons and electrons
2.
equal numbers of protons and neutrons
3
two electrons in the first shell
4.
two electrons in the outermost shell

Use examples from the article to explain one positive and one negative effect that chemistry has had on society

Plz choose one of the compounds from the table and explain how you know the numbers of atoms in your formula. is it possible for two different compounds to be made from the exact same two elements? why or why not? with a limited number of elements (less than 120 are known), does this mean we also have a small number of compounds or do we have a large number of compounds in this world?

Which best describes how johannes kepler developed his laws of planetary motion