Mendeleev's Periodic Table
The Modern Periodic Table
The periodic table is organized in periods and groups. Periods are horizontal columns and groups are vertical columns. To read an element you must first look at the name of the element. Then, you look at the chemical symbol. It is usually the first letters of the element. Next, you look at how many protons and electron are in the element. It is the number above the chemical symbol. Finally, you look at the atomic mass which is under the name of the element. For metals, if you go from left to fight the left is more reactive. For nonmetals it is the right side that is more reactive.
From lithium to francium are called alkali metals. Alkali metals react with other elements by losing one electron. These metal are highly reactive, and they are never found as uncombined elements in nature. Instead, they are found in compounds. As pure, uncombined elements, they are shiny and soft. The two most important alkali metals are sodium and potassium. Your diet includes sodium and potassium.
Group 2 contains the alkaline earth metals. They are hard, gray-white, and are a conductor of electricity. They react by losing two electrons. There not as reactive as the alkali metals, but still more reactive then the other metals. They are never found uncombined in nature. Magnesium and calcium are the most common alkaline earth metals.
Elements in group 3-12 are Transition metals. They are the most familiar metals. Most of them are hard and shiny. All of them are good conductors of electricity. These metals are less reactive then the ones in group 1 and 2. Some transition metals are important in your body. For example, iron in your blood stream.
Only some of the elements in groups 13-15 are metals. These metals are never found uncombined in nature. The most familiar of these metals are aluminum, tin, and lead.
The top row of the two lower rows under the periodic table are called lanthanides. Lanthanides are sometimes mixed with more common metals to make alloys. Different lanthanides are usually found in nature always combined with other elements.
The elements below the lanthanides are called the actinides. Only actinium, thorium, protactinium, and uranium occur naturally on Earth out of all the actinides. All of the elements after uranium were created in a laboratory.
Elements with an atomic number higher than 92 are called synthetic elements. These elements aren't found naturally on earth. Instead, scientist make them. They make them by forcing nucleus particles to crash into another. To make even heavier elements scientist use powerful machines called particle accelerators. Particle accelerators move atomis nuclei faster and faster until they reach high speeds. Curium was the first synthetic element.
Most nonmetals are poor conductors of electirc current and heat. Solid nonmetals are dull and brittle. Atoms of nonmetals usually gain or share electrons when they react with other atoms. Two examples are salt and rust.
In group only carbon is a nonmetal. Most fuels that burn have carbon. Coal is one example. Gasoline is another example.
The nitrogen family is in group 15. The nitrogen family contains only two nonmetals, nitrogen and phosphorus. Nitrogen is a diatomic molecule. In this form in isn't that reactive. Phosphorus is more reactive than nitrogen. Phosphorus in nature is always found in compounds.
The oxygen family is in group 16. The oxygen family contains three nonmetals, oxygen, sulfur, and selenium. Oxygen is a diatomic molecule. oxygen sometimes forms a triatomic molecule. oxygen is highly reactive. The smell of a rotten egg is sulfur. Sulfur is used in rubber for rubber bands and automobile tires.
In group 17 there is the halogen family. It contain fluorine, chlorine, bromine, iodine, and astatine. Halogen means salt forming. All halogens are very reactive, and the uncombined elements are dangerous to humans.
The elements in group 18 are inert gases. Inert gases are unreactive. inert gases are also known as noble gases. All inert gases exist in Earth's atmosphere, but only a small amount.
In the upper left corner of the periodic table is hydrogen. Most hydrogen atoms have one proton and one electron. Some also have neutrons. Since it is very different from other elements it can't be in a family.
Between the metals and the nonmetals in the periodic table lie the semimetals. They are listed in yellow squares. Semimetals have some properties of metals but also properties of nonmetals. The most common semimetal is silicon. Silicon combines with oxygen to form silicon dioxide. Sand is the main componet of the making of glass. The most useful property of a semimetal is their varying ability to conduct electric current. The electrical conductivity of a semimetal depends on temperature, exposure to light, or the presence of impurities. Semimetals are examples of semiconductors.
