Ions & Isotopes

Ions are charged atoms that have either gained or lost electrons.

Cations = positive chargeAnion = negative charge

Atoms prefer to have full outer orbitals, which is their most stable state. Atoms that have a nearly full or nearly empty valence shell are unstable and easily react to give/get e-’s.

Some *** Non-metals gain electrons and metals lose electrons.

Non-metals gain electrons while metals lose electrons.

Normal Stable

Be Cl

Be Cl

Create the stable ion form for the following atoms:

(must have full outer shell)

Na Mg

Br O

Isotopes are versions of an element with different #’s of neutrons. Some are stable while others are not.

Remember, that changing at atom’s protons changes what element it is.

Isotopes can be expressed in a couple of ways. For example, Carbon usually has 6 neutrons, but an isotope of C can have 8. This isotope can be written as:

• Carbon-14• .

How many e-, p+ and No does C-14 have?

14C

6

Carbon Isotopes

Carbon Isotopes

Fill in the following:

C-13P+:e-:No:

C-12P+:e-:No:

C-14P+:e-:No:

Average Atomic Mass

Different isotopes exist in different quantities. The atomic mass shown on the periodic table represents the AVERAGE mass of these isotopes.

How could the average mass be calculated?

Practice Q

1. If 2 atoms are isotopes that weigh 10amu and 15amu which are found in equal quantities, what is the average atomic mass?

2. Two isotopes of X-23 and X-30 have been found in nature. If the relative abundances of each are 75% and 25% respectively,

Calculate the average atomic mass of X.