February 29 and March 1 The Periodic Table

Periodic Table Organizes all elements by atomic number. Atomic number is how many protons the element has! Each element also shows the atomic mass. Atomic mass is the combined mass of protons and neutrons. The number of neutrons can vary in a given element so the atomic mass is an averaged value.

Columns The columns are called groups or families. The elements that go vertically have similar chemical properties. They share similar properties because they have the same number of valence electrons. There are exceptions in the center!

Rows The rows are called periods. The periods are organized by energy level. As we move down a period, we increase an energy level.

Q & A What is the name of the element with 26 protons? Iron How many electrons are in a neutral atom of sulfur? 16 If Oxygen gains two electrons, what element is it now? Oxygen…it is now just a -2 charge. What four elements have chemical properties most similar to fluorine? Chlorine, Bromine, Iodine, and Astatine

Organization We put the elements into 3 main groups Metals Nonmetals Metalloids Most elements are metals.

Metals Metals are found on the left side and the middle. Metals share a few properties… Conduct heat and electricity well Shiny Solid at room temperature (except mercury) Many in the middle are malleable (Cu and Au) Means they can be pounded into thin sheets Also are ductile which means they can be drawn into wire.

Nonmetals On the right side of the table. With the exception of Hydrogen (it is on the left because it reacts like a metal). Poor conductors of heat and electricity. Vary in appearance. At room temp. sulfur is a yellow crystal, nitrogen is a gas, and bromine is a red-brown liquid. Very far right is noble gases! These almost never form compounds with other elements.

Metalloids Found between metals and nonmetals. Have some properties of metals and some of nonmetals, but are neither one or the other. Silicon is a good example. It looks like a metal, but it is brittle. It also conducts heat and electricity better than a nonmetal, but not as well as a metal. Scientists call this a semiconductor.

Q & A Determine whether the following are metals, nonmetals, or metalloids… Ag Metal P Nonmetal Li Sb Metalloid I