Why is the Periodic Table organized the way it is? • Thanks to Dmitri Mendeleev!!! • He put the chemicals and their properties on cards. • He put them in order of their atomic weight.
Why is the Periodic Table organized the way it is? • He found that some of the properties repeated periodically. • He predicted some holes in the periodic table predict three new elements and a variety of their properties like their density. • They were later discovered having similar properties to what Mendeleev predicted. Germanium, Gallium, Scandium
Organization Now • Henry Moseley organized it by Atomic number • The noble gases were discovered and added later with out messing up the organization.
Valence Electrons • Valence Electrons: The outer most electrons in the s and p orbitals. • Write the noble gas notations for all of the alkali metals. • This works for all the groups!!
Valence Electrons • How many valence electrons in • The halogens? • The boron group? • The alkaline earth metals? • The noble gases? • Chemical reaction happen because of the valence electrons • This is why elements in the same group behave similarly
Periodic Trends!!! • Atomic Radii: half the distance between the nuclei of two atoms.
Atomic Radii The trend Why?
Ionization Energy • The energy required to remove an electron. • What do you think the trend is? • Why?
Electronegativity • The ability to attract an electron. • What do you think the trend is? • Why?