In all of these cases, the initial relative stability of the electron configuration disrupts the trend in EA. We also might expect the atom at the top of each group to have the largest EA; their first ionization potentials suggest that these atoms have the largest effective nuclear charges.
However, as we move down a group, we see that the second element in the group most often has the greatest EA. The electron is attracted to the nucleus, but there is also significant repulsion from the other electrons already present in this small valence shell.
The entering electron does not experience as much repulsion and the chlorine atom accepts an additional electron more readily, resulting in a more negative EA. Figure 6. The properties discussed in this section size of atoms and ions, effective nuclear charge, ionization energies, and electron affinities are central to understanding chemical reactivity.
For example, because fluorine has an energetically favorable EA and a large energy barrier to ionization IE , it is much easier to form fluorine anions than cations. Metallic properties including conductivity and malleability the ability to be formed into sheets depend on having electrons that can be removed easily.
Thus, metallic character increases as we move down a group and decreases across a period in the same trend observed for atomic size because it is easier to remove an electron that is farther away from the nucleus.
Electron configurations allow us to understand many periodic trends. Covalent radius increases as we move down a group because the n level orbital size increases. Covalent radius mostly decreases as we move left to right across a period because the effective nuclear charge experienced by the electrons increases, and the electrons are pulled in tighter to the nucleus. Anionic radii are larger than the parent atom, while cationic radii are smaller, because the number of valence electrons has changed while the nuclear charge has remained constant.
Ionization energy the energy associated with forming a cation decreases down a group and mostly increases across a period because it is easier to remove an electron from a larger, higher energy orbital. Electron affinity the energy associated with forming an anion is more favorable exothermic when electrons are placed into lower energy orbitals, closer to the nucleus. Therefore, electron affinity becomes increasingly negative as we move left to right across the periodic table and decreases as we move down a group.
For both IE and electron affinity data, there are exceptions to the trends when dealing with completely filled or half-filled subshells. The associated number e. Skip to main content. Search for:. Periodic Variations in Element Properties Learning Outcomes Describe and explain the observed trends in atomic size, ionization energy, and electron affinity of the elements.
Explore visualizations of the periodic trends discussed in this section and many more trends on the Atomic Number of the Elements website. With just a few clicks, you can create three-dimensional versions of the periodic table showing atomic size or graphs of ionization energies from all measured elements. Show Solution Ne or He. Show Solution Ba.
Key Concepts and Summary Electron configurations allow us to understand many periodic trends. Based on their positions in the periodic table, predict which has the largest atomic radius: Li, Rb, N, F, I.
Based on their positions in the periodic table, predict which has the largest first ionization energy: Mg, Ba, B, O, Te. Based on their positions in the periodic table, predict which has the smallest first ionization energy: Li, Cs, N, F, I. Based on their positions in the periodic table, rank the following atoms in order of increasing first ionization energy: F, Li, N, Rb Based on their positions in the periodic table, rank the following atoms or compounds in order of increasing first ionization energy: Mg, O, S, Si Atoms of which group in the periodic table have a valence shell electron configuration of ns 2 np 3?
Atoms of which group in the periodic table have a valence shell electron configuration of ns 2? Based on their positions in the periodic table, list the following atoms in order of increasing radius: Mg, Ca, Rb, Cs. Based on their positions in the periodic table, list the following atoms in order of increasing radius: Sr, Ca, Si, Cl. E represents an atom. This of course means that the outermost electrons will be closer to the nucleus.
Related questions What happens to ionic size down a group? What happens to ionic size across a period? How does ionic size change?
How does ion size affect conductivity? The correct option is : d S2-Explanation:Since all of these ions contain 18 electrons each so these are isoelectronic. For isoelectronic ions smaller the positive nuclear charge greater is the size of the ion.
S2- is the largest in size. S2- and Cl- have an extra shell than the other two and thus the two largest ions of the four. S2- and Cl- are isoelectronic and contain 16 and 17 protons respectively. What happens to ionic size across a period?
How does ionic size change? How does ion size affect conductivity? Can I determine the ion size by charge?
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