Atoms and Ions

To define atoms from ions, you need to know that atoms are electrically neutral and the number of protons equal the number of electrons. Whereas ions have different number of protons and electrons and they can either be positive (losing an electron) or negative (gaining an electron). Recall that a cation is a positive ion, and a anion is a negative ion.

Examples: Determine how many electrons each of the ions have. What type of ion are they? (cation or anion)?

F- gains 1 electron and is an anion
H+ loses 1 electron and is a cation
Ag+ loses 1 electron and is a cation
N3- gains 3 electrons and is an anion

Determine how many protons, neutrons and electrons the following substances have.

76As3- protons: 33 neutrons: 43 electrons: 36

Bohr Diagram for ions: Draw the Energy level Bohr diagram for the following ions.



Chemical Bonds:
A bond is an electrostatic attraction between particles that occur as elements try to achieve Noble gas electron configuration. Noble gases (usually) don't form compounds or bonds, and in Noble gases, the outermost energy level have stable octets. Recall that metals lose electrons (oxidize) and non metals gain electrons (reduced).

Lewis Dot structure:
Since atoms can be represented by dot diagrams, the dots are represent electrons, however, only valence electrons are shown. The first step is to write the atomic symbol for the atom, which represents the nucleus and filled inner electron levels. One dot is used to represent outer energy level electrons. Only one e- is placed in each orbital before any pairing occurs. Beginning with the 5th e-, pairing can occur, however, only up to a maximum of 8e-.

Ionic Bonds:
Electrons are transferred from metal to non metal, but no dots are shown on metals. Also, "charged" species are written in brackets.