1. ENC Practice

2. If ENC increases, size _____ Size decreases ENC pulls the electrons in tighter, therefore the total size of the atom (created by the electron cloud) is smaller

3. What happens to Electron Affinity as ENC decreases Electron Affinity decreases as ENC decreases Electron Affinity is the change in energy as an atom gains an electron If an atom “wants” an electron more (higher ENC), it will release more energy when it gains the electron

4. Why do atoms get larger as you go down a family? There are the same number of valence electrons, so they all have approximately the same ENC As you go down a period, an extra layer of electrons are added (you increase energy levels) Extra energy levels need space, so the atom gets bigger

5. Which element has the highest ENC – Si, I, Mg, Al? ENC ~ # valence electrons I has 7 valence electrons – ENC ~ 7 Si has 4 valence electrons – ENC ~ 4 Al has 3 valence electrons – ENC ~ 3 Mg has 2 valence electrons – ENC ~ 2

6. Which element has the highest ionization energy – Se, Ba, Rb, Cl Higher ENC -> higher IE Se has 6 valence electrons – ENC ~ 6 Ba has 2valence electrons – ENC ~ 2 Rb has 1 valence electrons – ENC ~ 1 Cl has 7 valence electrons – ENC ~ 7

7. Which atom will become a negative ion easiest – O, Xe, Ca, Li O has 6 valence electrons, wants 2 more, has the best electron affinity Xe has a higher ENC, but has 8 valence electrons and wants no more