Aim: What are the Properties of Groups and how does the atomic radius change across a period and down a group ? Do Now: 1. Take out your periodic tables. 2. Come to the front of the desk and pick out your colored pencils/crayons.
Periodic Trends Many trends of elements can be explained by electron configuration and position on the periodic table Trends to be examined Atomic radius Ionic radius Ionization energy electronegativity
Atomic Radius The distance from the center of the nucleus to the outermost shell. Table S has the atomic radii values.
Atomic Radius- Down a Group: A Closer Look at Lithium and Sodium As you move down a group or family the atomic radius increases due to more energy levels.
Atomic Radius – Across a Period Same number of energy levels, but Be has more protons pulling on the outer electrons, making Be smaller. As you move across a period, the atomic radius becomes smaller due to increasing # of protons.
Which has the largest atomic radius? Chlorine Fluorine Iodine Bromine
Ions An ion is an atom that has gained or lost electrons to have a full outer shell (8 electrons) like the noble gases.
Ions cont. Atoms that gain electron(s) are called an anions, and have an overall negative charge. ClCl - atomanion Atoms that lose electron(s) are called cations, and have an overall positive charge. NaNa + atom cation
Ionic Radius The distance from the nucleus to the outermost electron of an ion.
Ionic Radius Sodium – Atom Sodium - Ion
Ionic Radius The sodium ion loses the outer most electron to have a full outer shell. The ion is now smaller than the atom. It has one less electron making it have a +1 charge.
Ionic Radius Metals tend to lose electrons (form cations) while nonmetals tend to gain electrons (form anions). Metal ions are smaller than their atoms; nonmetal ions are larger than their atoms.
For each set of elements select the one with the smallest radius and give a reason for your choice. Set 1: C, N, O, F Set 2: F, CL, Br, I Set 3: Na, K, Na +, K + Set 4: Na +, K +, Mg 2+, Ca 2+ Set 5: F, F -, Na, Na +