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Periodic table By Christian paredez Hydrogen • Hydrogen is the lightest element • Hydrogen as water (H2O) is absolutely essential to life and it is present in all organic compounds. • Hydrogen is the lightest gas. • Hydrogen was discovered by Henry Cavendish at 1766 in London. Helium • Helium is one of the so-called noble gases • Helium gas is an unreactive, colorless, and odorless monoatomic gas. • Helium is the second most abundant element in the universe. • Helium was discovered by Sir William Ramsay. Lithium • Lithium is a solid. • A freshly cut chunk of lithium is silvery • It is the first element within the second period. • Lithium was discovered by Johan August Arfvedson at 1817 in Stockholm, Sweden. Beryllium • • • • Beryllium is a Group 2 (IIA) element. Beryllium resists oxidation in air. Beryllium compounds are very toxic. Beryllium was discovered by Nicholas Louis Vauquelin. Boron • It is a semiconductor rather than a metallic conductor. • Chemically it is closer to silicon than to aluminum, gallium, indium, and thallium. • Crystalline boron is inert chemically and is resistant to attack by boiling HF or HCl. • Boron was discovered by Sir Humphrey Davy. Carbon • It is found in abundance in the sun, stars, comets, and atmospheres of most planets. • Carbon is found free in nature in three allotropic forms. • Graphite is one of the softest known materials while diamond is one of the hardest. • Carbon was discovered by Known since ancient times Nitrogen • Nitrogen is a Group 15 element. • Nitrogen makes up about 78% of the atmosphere. • However, its compounds are vital components of foods, fertilizers, and explosives. • Nitrogen was discovered by Daniel Rutherford in 1772. Oxygen • Oxygen is a Group 16 element. • Mars contains only about 0.15% oxygen. • Oxygen is the third most abundant element found in the sun. • Leonardo da Vinci suggested that air consists of at least two different gases. Fluorine • Fluorine is the most electronegative and reactive of all elements. • It is a pale yellow, corrosive gas, which reacts with practically all organic and inorganic substances. • Finely divided metals, glass, ceramics, carbon, and even water burn in fluorine with a bright flame. • Fluorine was discovered by Henri Moissan at 1886 in France. Neon • Neon is a very inert element. • Neon forms an unstable hydrate. • In a vacuum discharge tube, neon glows reddish orange. • Neon was discovered by Sir William Ramsay Sodium • Sodium is a Group 1 element. • The chemistry of sodium is dominated by the +1 ion Na+. • Sodium salts impart a characteristic orange/yellow color to flames and orange street lighting is orange because of the presence of sodium in the lamp. • Sodium was discovered by Sir Humphrey Davy at 1807 in England. Magnesium • Magnesium is a grayish-white, fairly tough metal. • Magnesium is the eighth most abundant element in the earth's crust. • Magnesium metal burns with a very bright light. • Black recognized magnesium as an element in 1755. Aluminum • Pure aluminum is a silvery-white metal with many desirable characteristics. • It is somewhat decorative. It is easily formed, machined, and cast. • Pure aluminum is soft and lacks strength. • The ancient Greeks and Romans used alum in medicine as an astringent Silicon • Silicon is present in the sun and stars and is a principal component of a class of meteorites known as aerolites. • Silicon makes up 25.7% of the earth's crust. • It is found largely as silicon oxides. • Jacob Berzelius is generally credited with the discovery of silicon in 1824. Phosphorus • It is an essential component of living systems. • Found in nervous tissue, bones and cell protoplasm. • Phosphorus exists in several allotropic forms including white. • Phosphorus was discovered in 1669 by Hennig Brand Sulfur • Sulfur is a pale yellow, odorless, brittle solid. • Which is insoluble in water. • It is a minor constituent of fats, body fluids, and skeletal minerals. Sulphur was known in ancient times and referred to in Genesis as brimstone Argon • Argon is a colorless and odorless gas • Argon is very inert (indeed it is referred to as one of the noble gases) and is not known to form true chemical compounds. • Argon was discovered by Lord Rayleigh and Sir William Ramsay in 1894. Potassium • Until the 18th century no distinction was made between potassium and sodium. • potassium carbonate was mixed with animal fat to make soap. • Potassium was discovered by Sir Humphrey Davy at 1807 in England. Calcium • Calcium as the element is a grey silvery metal. • The metal is rather hard. • Calcium was discovered by Sir Humphrey Davy at 1808 in England. scandium • develops a slightly yellowish or pinkish cast upon exposure to air. • Scandium is a silvery-white metal which • Scandium was discovered by Lars Fredrik Nilson at 1879 in Sweden. Titanium • Titanium s a lustrous, white metal when pure. • Titanium minerals are quite common. • Titanium was discovered by the Reverend William Gregory in 1791. Vanadium • Pure vanadium is a greyish silvery metal. • is soft and ductile. • Vanadium was discovered by Andres Manuel del Rio and Nils Sefström at 1801 in Mexico. Chromium • Chromium is steel-gray, lustrous, hard, metallic. • takes a high polish. • Chromium was discovered by Louis-Nicholas Vauquelin at 1797 in France. Manganese • Manganese metal is gray-white. • is harder and very brittle. • Manganese was discovered by Johann Gahn at 1774 in Sweden.