Tutor profile: Joe V.

Why is Oxygen diatomic?

All atoms are "happiest", or most stable, when their valence (or outermost) electron shell is complete. The valence shell of the Oxygen atom has room for 8 electrons, but a single atom of Oxygen has only 6 electrons in its valence shell. So, in order to be more stable, 2 Oxygen atoms will create a double bond in which they share four electrons. If both Oxygen atoms donates two electrons to this double bond, then each Oxygen will have a full valence shell of 8 electrons, four of which are contained in the double bond, and the other four in a set of two lone pairs on each Oxygen atom.

How do viruses make us sick?

Viruses "hijack" the parts of your cells which build the molecules that your body needs, and trick them into making more viruses instead. Sometimes your cells make so many viruses that they burst open, killing the cell. Your body has special cells called white blood cells which try to kill infected cells before they can be used to make more viruses. The chemicals they use to do this are very powerful, and can even give us a fever to try and cook the viruses alive!

Why can't you take the square root of a negative number?

When you take the square root of a number, for example X, you are essentially asking: "What number squared equals X?" Since we know that any number squared, either positive or negative, must equal a positive number, there is no real number that is the square root of a negative number.