<p>What is the periodic trend for "first" and "second" ionization energy going across a period? Give examples if necessary.</p>
<p>second ionization energy > first i.e.
generally the ionization energy should increase as you go across periods b/c the electronegativity increases. second ionization energy really depends on the suborbitals filled.</p>
<p>I'm guessing that second ionization energy is higher than first ionization energy because of the shielding effect. Is this right?</p>
<p>I am not quite sure about shielding, but... It's pretty much like this: closer you get to the nucleus, harder it gets to pull away the electron, as smaller distance increases the attraction effect.</p>
<p>second ionization energy is higher because the proton number remains the same while the electron number decreases. so less shielding effect, if you want to put it that way.</p>
<p>oh yea, that's another reason</p>
<p>Calcium has higher 2nd because doesn't it have to take away electrons at two different principal energy levels with 2nd ionization energy</p>