The hydrogen atom is the simplest one known, consisting of one proton and one electron. The helium atom, which scientist studied next has 2 protons and electrons, yet its mass is 4 times that of hydrogen, can you say why?

How many moles of magnesium is 3.01 x10^22 atoms of magnesium?

Which element has the lowest electronegativity? calcium(ca) gallium(ga) selenium(se) bromine(br)

Two metal blocks that have slightly different temperatures are placed next to one another. after five minutes, they both have lower but equal temperatures. according to the law of conservation of energy, what  most likelyhappened? energy was created inside the blocks.energy was destroyed inside the blocks.energy was absorbed into the blocks from outside the system.energy was transferred from the warmer block to the cooler block.