2.5 Periodic patterns of atomic and ionic radii Flashcards
Define atomic radius
The covalent atomic radius is half the distance between thenuclei of two covalently bonded atoms of the same type
What are stable metal ions and stable nonmetal ions?
These are ions with the electronic configuration of an ion
What is the pattern of atomic radius down the group?
The atomic radius increases down any group. This is because, going down any group, each successive ion has one or more shell of electrons which is further from the nucleus. Although there us also an increasing nuclear charge down the group, the increased effect of inner shell electrons shielding the outer shell electrons is more important
What is the pattern of atomic radius down the group?
The atomic radius decreases across any period. This is because the number of protons, and therefore the nuclear charge, increases by one with each successive element. The number of electrons also increase by one but the extra electron added goes into the same (outer) energy level. This means that the shielding does not change significantly. The greater the attractive forces of the increased nuclear charge on the on the outer shell electrons pulls them closer to the nucleus.
Describe the pattern of ionic radius down any group for ions with the same charge
The ionic radius increases down any group. Going down the group, each successive element has one more shell of electrons which is further from the nucleus. The increased effect of inner shell electrons shielding the outer shell electrons is more important than the effect of increased nuclear charge.
What is the pattern of ionic radius across the period from Group 1 to 14
The ionic radius decreases. This for similar reasons to those for decreasing atomic radii across a period. The increasing nuclear charge attracts the electrons in the outer electron shells closer to the nucleus with increasing atomic number. The shielding is approximately the same so it has less effect than the increase in nuclear charge. The charge is generally greater than their original atom because they have lost their outer shell electrons.
Positively charged ions are smaller than their original atoms because
they have lost their outer shell electrons
What is the pattern for the ionic radius across the period for group atoms in group 15 to 18
The ionic radius decreases. This is for similar reasons to those for decreasing atomic radii across a period and due to the normal charge on the ions decreasing.
Negatively charged ions in Group 15 to 18 are larger than their original atoms because
Each atom will have gained one or more extra electrons in their outer energy level.
Why does the first ionization energy decreases as you go down a group in the Periodic Table.
This is because the distance between the nucleus and the outer electron increases as well as the shielding by complete inner shells increases. These two factors outweigh the increased nuclear charge.
