Aim: How are elements classified? Elements can be differentiated by their physical properties: density, conductivity, malleability, solubility, and hardness; and chemical properties: how an element behaves during a chemical reaction. The succession of elements within the same group or period demonstrates characteristic trends: differences in atomic radius, ionic radius, electronegativity, first ionization energy, and metallic/nonmetallic properties.

Aim: How are elements classified? Ionization Energy- The amount of energy required to remove the most loosely bound electron from a neutral atom. Essential questions: Why does ionization energy increase across a period? Why does ionization energy decrease down a group?

Aim: How are elements classified? Atomic radius- the size of the atom; half the distance between two adjacent atoms ( measured in picometers.) Essential questions : Why does atomic radius DECREASE across a period? Why does atomic radius increase down a group?

Aim: How are elements classified Ionic radius- distance from the radius to the outer energy level of the ion. Essential questions: Why is the radius of a metallic ion smaller than the radius of the atom? Why is the radius of a nonmetallic ion greater than the radius of the atom?

Aim: How are elements classified? Elecronegativity- measure of an atom’s attraction for electrons when bonded to another atom; a relative measure of how strongly the nucleus of an atom will attract electrons from another atom. Essential questions: Why does electronegativity increase across a period? Why does electronegativity decrease down a group? Periodic trends