The Elements Pratically

Hydrogen, helium and elements 7 to 10, 17, 18, 36, 54, and 86, are gas. Bromine and mercury are liquids. All others are solids. Elements 43, 84 to 88, 104 to 118, all lanthanides and all actinides, are radioactive. Elements 43, 104 to 118, 61, 93 to 103, are artificially made

One useful classification which springs out of the Mendeleiev table is the one between the alkali metals, alkaline earth metals, transition metals, halogens and noble gases, providing a good overview of the various chemical elements found on Earth, like described below. A other view is that, the lanthanides and actinides excluded, the table is having the alkali elements to the left, halogens to the right, elements basic to life to the upper right as all the rest in between are mere metals

• alkali metals are lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). Such 'metals' are highly reactive, hence never found in nature in elemental form. They have to be stored under the form of a mineral oil. Such elements are silver-colored, soft and have a low density
• alkaline earth metals are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra). Such metals are silvery colored, soft and have a low density. They react easily with halogens to form ionic salts
• transition metals are the 40 chemical elements 21 to 30, 39 to 48, 71 to 80, and 103 to 112. Mercury, copper, zinc, gold, cadmium are part of the category. Such elements are silvery-blue, solid. They have a high density and a high melting and boiling points
• halogens are fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At). Such elements, in union with a metal, produce salt. They are highly reactive and can be harmful or lethal to biological organisms (chlorine, for example, is used like a disinfectant for drinking water or swimming pools)
• noble gases are helium, neon, argon, krypton, xenon, and radon. They have an extremely low chemical reactivity as they are used in lighting, serving like an inert atmosphere for light bulbs

The lanthanides are the 15 elements with atomic numbers 57 through 71, from lanthanum to lutetium, along with scandium and yttrium. They are also called "rare earths". Such materials are mostly used in lasers or in the optical industry to manufacture sunglass lenses due to their ability to deflect UV and infrared rays. Actinoids, at last, are the 15 chemical elements lying between actinium and lawrencium, with atomic numbers 89 - 103. They are the famed 'radioactive' elements, like uranium or plutonium. Three of them only -actinium, thorium, and uranium- occur naturally on Earth. Other have been synthesized in the 20th century. As the previous categories sort from similarities along the vertical lines of the Mendeleiev table (such groupings are called a 'group'), lanthanids and actinids sort on the horizontal level of the table (which is called a 'period')