How many elements are there

Magnesium has three naturally occurring isotopes. The most common, magnesium-24, accounts for nearly 80% of the magnesium found in nature. The atomic numbers and mass numbers for four different atoms are shown in the table below.

What is the definition of half-life?

How many degenerate orbitals are needed to contain six electrons with two of them unpaired?

A chemist weighed out 65.8 g of potassium. Calculate the number of moles of potassium she weighed out. Round your answer to 3 significant digits.

Which ozone-depleting chemical is not matched with its proper use?

What substance is not a compound

Consider the following exothermic reaction and predict how the change below will affect the concentration (increase, decrease, stay the same) of each component in the system as the equilibrium is reestablished.

How does the electron structure of atoms change when they form chemical bonds

What is the scientific notation for 1073

What is the force that opposes the sliding motion of two touching surfaces?