K. Culbertson Chemistry 2011 Periodic Trends K. Culbertson Chemistry 2011

Representative Elements s & p blocks Why representative elements? They exhibit a wide range of physical and chemical properties

#1 Periodic Law Many of the physical and chemical properties of the elements tend to recur in a systematic manner with increasing atomic number Periodic Trends Trends that repeat at regular intervals (across periods or down groups)

#2a Atomic Radius The distance from the nucleus to the outer electrons The size of an atom

#2b Ionization Energy The amount of energy required to remove the outermost electron of an atom of an element Energy needed to remove an electron Na + energy  Na+ + e-

#2c Electronegativty The tendency for an atom to attract a pair of electrons when it is combined with another atom in a chemical bond Attraction for an electron of another atom

Why use straws? To make a 3-D model of the properties of elements.

Atomic Radius of Oxygen 73 pm x 1 cm = 2.43 cm 30 pm 2.4 cm (rounded to nearest tenth)

Ionization Energy of Neon 2081 kJ x 1 cm = 5.20 cm 400 kJ 5.2 cm (rounded to nearest tenth)

Electroneg. of Arsenic 2.2 (units) x 1 cm = 2.75 cm 0.8 (units) 2.8 cm (rounded to the nearest tenth)