Metals, Nonmetals, Metalloids and the Periodic Table

The First Periodic Table In the 19th century Dmitri Mendeleev designed the first periodic table of elements, in order of increasing atomic mass: the average mass of all the isotopes of a given element. Today our table is in order of increasing atomic number: number of protons in the nucleus. The atomic mass for most elements ends in a _______, because most elements are made up of a random mixture of isotopes. Atomic mass is found by calculating a weighted average of the percentages of all isotopes in a given element.

Organizing the Periodic Table The properties of an element can be predicted from its location in the periodic table. Periods: the __________ that contain a series of different elements. There are seven periods. Groups (families): are ___________ of elements that share certain properties. They are labeled group 1 to 18 and are named after the 1st element in that group.

Metal Groups A metal is a class of elements characterized by its physical and chemical properties. Physical Properties Luster: __________ Malleability: ability to be hammered/rolled flat Ductility: ability to be pulled/stretche into a long wire Conductivity: ability of an object to transfer _______ or __________ to another object Chemical Properties __________: the ease with which an element combines with another Most metals react by losing electrons to other atoms.

Metals by Group The reactivity of metals decreases from left to right across the periodic table, because elements have more valence electrons. Group 1: Alkali Metals React by losing one electron, and very reactive Group 2: Alkali Earth Metals React by losing two electrons Groups 3-12: Transition Metals More stable metals Groups 13-15: Metals in Mixed groups In these groups only SOME elements are metals

Synthetic Elements Elements above #92 are made artificially when nuclear particles are forced to crash into one another at high speeds, using a particle accelerator. When atoms move this fast their atomic nuclei can sometimes bombard other nuclei and combine into a single nucleus with extra protons. Example: plutonium is made by bombarding uranium nuclei in a reactor.

Nonmetals A nonmetal is an element that lacks the properties of metals. Poor conductors of electricity/heat but they are reactive with many metal elements. _______ or share electrons in chemical reactions. Group 14: Carbon Family Elements in this family gain, loses, or share four electrons. Group 15: Nitrogen Family React by gaining three electrons Group 16: Oxygen Family React by gaining _______ electrons Group 17: Halogen Family Highly reactive elements, gain one electrons Group 18: Noble Gases Highly stable and unreaactive

Metalloids Share characteristics with _______ and nonmetals. There are a total of ____ metalloids. Metalloids are solid, brittle, and hard. Most useful property is their varying ability to conduct electricity. They are used to make semiconductors: substances like computer chips that can conduct electricity under some conditions but not under other conditions. Silicon (Si)f is the most common metalloid. It is found in sand, glass, and computer chips.