Recap of The Octet Rule. Atoms tend to gain, lose, or share electrons until they have eight valence electrons. Hydrogen is an exception. It shares only one electron to reach an outer shell of two electrons.
Atoms tend to gain, lose, or share electrons until they have eight valence electrons.
Hydrogen is an exception. It shares only one electron to reach an outer shell of two electrons
This helpful picture will act as a visual way to remember this – in the exam this will help.
That means that they have an equal number of
protons and electrons.
During the course of most natural events,
protons are not gained or lost, but electrons may be.
Atoms with more or fewer electrons than protons are
electrically charged. They are called ions:
an atom that loses electrons takes on a positive charge (cation);
an atom that gains electrons takes on a negative charge (anion).
An ionic bond is formed usually when an electron is transferred from a metal to a non-metal and is the attraction between a +ve ion and –ve ion
Sodium gives up an electron to chlorine.
This makes chlorine very happy, as it now has eight valence electrons.
However – Sodium was being sneaky because he needed to get rid of that electron. Sodium is very happy, as it also now has eight valence electrons.
The animation above the process that takes place during the formation of an ionic bond. The individual atoms are sodium and chlorine with only their valence electrons shown. Note that chlorine has seven valence electrons (it wants a full shell of eight), and that sodium has one valence electron (it also wants a full shell of eight).
Ionic Bonds: One big greedy thief dog!
Ionic bonding can be best imagined as one big greedy dog steeling the other dog's bone. If the bone represents the electron that is up for grabs, then when the big dog gains an electron he becomes negatively charged and the little dog who lost the electron becomes positively charged. The two ions (that's where the name ionic comes from) are attracted very strongly to each other as a result of the opposite charges.
Mr . Hall would be very proud of that
Most minerals are held together by primarily ionic bonds.
INCASE : The ionic bond NaCl may not have sunk in yet so here it is againn.
WE LOVE NaCL
Atoms may form multiple covalent bonds - ie, share not just one pair of electrons, but two or more pairs. Atoms of different elements will form either one, two, three or four covalent bonds with other atoms.
The OCTET Rule
An easy example is Chlorine, Cl2
Chlorine atoms (unstable)
Chlorine molecules (stable)
Covalent bonds are strong and a lot of energy is needed to break them. Substances with covalent bonds often form molecules, such as hydrogen and water, with low melting and boiling points.