Question #92235
1 Answer
Metallic properties decrease from left to right across a period and increase from top to bottom down a group or family.
Explanation:
Metallic properties are created by the loss of electrons, creating a sea of loose electrons and a positive charge.
Atoms like sodium with few electrons have a very low electron negativity. The low electron negativity and the ability to easily lose electrons create metallic properties.
Across a period atoms have more electrons, the electron negativity increases making it less likely that the atom will lose electrons. Group IV has four valance electrons. Atoms in this family can lose or gain four electrons. If the Group four gains electrons it act as a non metal if it gains four electrons it will act as a metal. Group VII has seven valance electrons. Group VII atoms will usually gain one electron to become stable making them non metals.
Going down a group the atoms become larger. The larger the distance the outer electrons are from the nucleus the easier it is for the atom to lose electrons. Losing electrons increases metallic properties.
This tendency can be seen in Group IV. Carbon the top member of this group is considered a non metal will some metallic properties in its graphite form. Silicon the next member going down is considered a metalloid. This makes it a valuable semi conductor in computer applications. Sometimes Silicon loses electrons and sometimes gains them. Lead the bottom member of the group is considered a metal. It always loses electrons.
Going across a period metallic properties decrease from left to right.
Going down a group metallic properties increase from top to bottom.
