# Ionization Energy?

1. Mar 28, 2005

### Twigs

How can you find the Ionization Energy if given the charge and electron level?

2. Mar 29, 2005

### dextercioby

In general,ionization energies are tabulated and are given only for the last shell electrons.By charge i think u might mean Z and electron level,the orbital containing the electron wich would get expelled.

So,there's no general formula,just experimental values.

Daniel.

3. Mar 29, 2005

### Galileo

It kinda depends on the state of the atom. The ionization energy would be the energy required to remove an electron from the atom and thus ionizing it.
For example, the ionization energy of Helium (in the groundstate) is the difference in energy between it's groundstate and the groundstate of He+.

4. Mar 29, 2005

### dextercioby

Tabulated values are for ground state electrons only.

Daniel.

5. Mar 29, 2005

### SpaceTiger

Staff Emeritus
It's certainly true that for atoms with many electrons, you're best off going to a table for these things, but there are formulae for simple atoms and approximations for states that aren't tabulated. For example, hydrogen-like ions (i.e. with one electron) follow:

$$E \simeq 13.6\frac{Z^2}{n^2}~eV$$

High-Z two-electron atoms can be approximated with a similar formula:

$$E \simeq 13.6\frac{(Z-1)^2}{n^2}~eV$$

There are many analytical/numerical approximations to the energy levels of more complicated atoms, so perhaps you can be more specific about what you're looking for.

Last edited: Mar 29, 2005
6. Jul 19, 2005

### Troy

$$Z^2_eff$$ tttttt