Forming Molecules with Atoms

This tiny drop of water is really made of millions of tiny molecules And those millions of molecules are made up of tiny atoms, ah! Can you believe it? Amazing! It all starts with the atom! In their natural state, an electrically neutral atom has the same number of negatively charged electrons as it has positively charged protons The protons are found in the nucleus and the electrons are located around the nucleus The electrons are distributed in shells The first shell can hold two electrons, the second can hold eight And the third can hold eighteen The electrons in the most outer shell of a particular atom are called its valence electrons Atoms react chemically in bond with other atoms with these valence electrons Atoms are real control freaks They are always trying to fill their shells If an atom has one electron in its second shell It will try to lose one electron or gain seven But let me tell you, it is much easier to lose one With more than three valence electrons, it's easier to gain electrons by sharing them with other atoms Let's look at hydrogen It's in the first group of the periodic table It only has one electron in the outer shell Just like all the other elements in the same group Because elements in the same group have similar chemical and physical properties All of these elements bond very easily with other elements that like to gain one electron Hydrogen is a bit unusual since it only needs one electron not seven, to fill its shell Hydrogen is happy to share an electron with another atom to fill its shell Take our drop of water for example One water molecule is made up of two hydrogen atoms and one oxygen atom The oxygen atom has six electrons in its outer shell or a valence number of six It would love to gain two electrons Each hydrogen atom has a valence number of one And when the three of them get together They really bond!! Behold! the water molecule