Ionization Energies increase going left to right across a period and increase going up a group. As you go up a group, the ionization energy increases, because there are less electron shielding the outer electrons from the pull of the nucleus. Therefore, it requires more energy to out power the nucleus and remove an electron.
The effective nuclear charge is the difference between the total charge in the nucleus the number of protons and the number of shielded electrons.
Notice how as the effective nuclear charge increases, so does the ionization energy. Overall the general trend for ionization energy is shown below. Sample Question What would be the effective nuclear charge for Cl? Would you predict the ionization energy to be higher or lower than fluorine?
Chlorine has the electronic configuration of [Ne]3s23p5 The effective nuclear charge is 7, the same as fluorine. Predicting the ionization energy would be difficult with this alone.
The atomic size, however, is larger for chlorine than for fluorine because now there are three energy levels chlorine is in Period 3. Now we can say that the ionization energy should be lower than that of fluorine because the electron would be easier to pull off the level further away from the nucleus.
Some Anomalies With the Trend in Ionization Energy[ edit ] There are a few anomalies that exist with respect to the ionization energy trends.
Going across a period there are two ways in which the ionization energy may be affected by the electron configuration. When we look at period 3, we can see that there is an anomaly observed as we move from the 3s sublevels to the 3p sublevel. The table below shows the electron configurations for the main group elements in period 3 along with the first ionization energy for these elements.Jul 19, · A short discussion of the trends that arise related to reactivity.
Aug 23, · The experiment we did was about Periodic Trends. We determined the trend of reactivity of nonmetals down a group, the trend of reactivity of metals along a period and the trend of acidic properties of elements along a period. The halogens used were Cl2, Br2 and I2. Metals used were Sodium, Magnesium (magnesium ribbon), Status: Resolved.
The ionization energy is equal to the negative of the orbital energy of an electron: () E + − E G = − ɛ 1 ⋅ To calculate the electron affinity energy we need to consider a determinant as large as 3 × 3, but this proves easy if the useful Slater–Condon rules (Appendix M) are applied.
This leads to smoothly varying trends in properties such as ionization energy, electronegativity, ionization energy, and atomic radius as one moves both down the groups and across the periods.
Thus, the organization of the periodic table is useful for making predictions about an element based on its position in the table.
The term ionization potential is an older name for ionization energy, because the oldest method of measuring ionization energies was based on ionizing a sample and accelerating the electron removed using an electrostatic potential.
What is reactivity? Reactivity refers to how likely or vigorously an atom is to react with other substances (atoms, molecules, etc).
This is usually determined by how easily electrons can be removed (we call it ionization energy!) and how badly they want to take other atom's electrons (we call it electronegativity).