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The Elements On Our Earth Elements in the Atmosphere • Our atmosphere contains many elements that we need in order to survive… – Nitrogen (N) gas in the atmosphere consists of N2 molecules (it is a diatomic molecule). – Oxygen (O) is found as O2 molecules. – Argon is found as a single, uncombined Ar atom. – Carbon Dioxide is released by us into the atmosphere as CO2. Elements on the Earth • Our hydrosphere consists of all the water that occurs at the earth’s surface. – The chemical formula for water is H2O. Elements in the earth’s Crust • The earth’s crust contains many elements such as Oxygen (O2), Silicon (Si), Aluminum (Al), Iron (Fe) and others! • Oxygen is the most abundant element. It is also very reactive. • Oxygen reacts with other elements for form solid mineral compounds (ie. sand) Reactivity • How strongly an elements reacts with other elements is an important chemical property called reactivity Other elements • Metals • • • • • • All metals have certain properties in common Metals conduct electricity and heat Malleable and ductile Solid state at room temperature (except mercury) Shiny in appearance Ex. Tin, Aluminium, Iron • Non Metals • Have very different properties than metals • Can be gases or solids (only 1 liquid – bromine) at room temperature • Not shiny • Poor conductors of heat and electricity • Brittle, Non-ductile • Ex. Hydrogen, Carbon, Sulfur • Metalloids • • • • • • • Have properties of both metals and non-metals Solids at room temperature Can be shiny or dull May or may not conduct electricity Poor conductors of heat Brittle and non-ductile Ex. Silicon, Boron, Arsenic Extraction of Metals • Most metals are reactive and have to be contained in other compounds. • These metals are mostly found in minerals • A mineral is a solid pure substance that occurs naturally in the earth’s crust • Mineral deposits are found in ores in the earth’s crust • The minerals have to be extracted from the earth Extraction of Metals • When the ore is collected, the mineral goes through a process of concentration (to collect as much mineral as possible) • Once in mineral form, a process called decomposition allows the metal to be extracted and the excess unwanted materials are discarded