Which two elements in the periodic table have the same number of electrons in their outer orbitals?

what property of the noble gases most likely prevented the gases from being readily/easily discovered?

One difference between mixtures and pure substances is that A) mixtures can be physically separated. B) mixtures are made of one type of atom. C) pure substances have no chemical bonds. D) pure substances can be physically separated.

How did an early understanding of gases lead to a better understand of the atom

Which property of gases allows them to be stored at high concentrations in a bottle of air freshener?

If the ozone layer gets significantly thinner in your lifetime, what changes do you need to make in your lifestyle?

C₂H₂ + O2 - CO₂ + H₂ How many moles of oxygen are necessary to react completely with 4.0 moles of propane (CH) ?

What are the two main classifications of energy resources?

A liquid is heated and a solid forms at the bottom of the beaker. Is this a physical or chemical change?

How to predict the formula of an ionic compound based on the charges of the ions?

Which of the following kingdoms in one-celled organisms