Periodic Table • Russian chemist Dmitri Mendeleev in 1869 and b • The Periodic Table of Elements is used to organize elements based on • physical properties such as • hardness (brittle or malleable) • conductivity (thermal and electrical) • chemical properties such as • reactivity • flammability
Periodic Properties of the Elements Periodic describes something that occurs in regular intervals. The elements properties repeat every seven elements
The rows are read left to right • The horizontal rows are called periods • Row # = # of energy levels in electron cloud • Lower rows = larger atoms (bigger diameter) • Atomic mass increases from left to right across a period.
Vertical columns are called groups or families • Column # (group #) = # of valence electrons • Elements in same group have similar chemical and physical properties
M E T a L L O I D S Non Me t a l S Metals, Non-Metals and Metalloids ME T A L S
Five Elements to Know: H C O Al Fe
Oxygen • Gas at room temp. • Highly reactiveelement! • Combines easily with other elements to form compounds called “oxides”: iron oxide (rust), copper oxide, carbon dioxide. • At high enough temp, many substances react violently with oxygen - combustion (burning) • Used by most organisms for cellular respiration. • Makes up 21 % of earths atmosphere.
Is a gas Simplest and most abundant element in universe Scientists estimate ¾ of universe is hydrogen! Stars made of mostly hydrogenUsed as rocket fuelHIGHLY FLAMMABLE and REACTIVE
The Hindenberg Disaster • May 6, 1937 in Lakehurst NJ. • German airship bursts into flames trying to land. • It was filled with hydrogen gas. • Completely incinerated in just over 30 seconds. • 62 out of 97 people survived.
Is a non metal • Mostly obtained from coaldeposits. • Black soot from burning wood is mostly carbon. • Graphite - form of carbon used in pencils. • Diamond– • Carbon +pressure+ heat + time = Diamond
Combines with other elements to make organic compounds like proteins, fats, and carbohydrates. • Most important element for living things!
One of most abundant of all metals. • Used to make steel (iron + carbon). • Helps to oxygenate the blood and makes it red. • Iron is a magnetic metal. • Good conductor. “Iron Age” approx. 1200 B.C. - 300 B.C.
Very conductive metal. • Lightweight (low density) but strong. • Used in cans, foil and kitchen utensils, parts of airplanes and cars.