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Bonding Unit

Bonding Unit. Atoms, Elements, Molecules, compounds and Mixtures notes. Elements. Pure substances that contain only one kind of atom. Examples: Hydrogen, Copper, Iron. Atoms –vs.- Molecules. Some elements exist as single atoms .

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Bonding Unit

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  1. Bonding Unit Atoms, Elements, Molecules, compounds and Mixturesnotes

  2. Elements • Pure substances that contain only one kind of atom. • Examples: Hydrogen, Copper, Iron

  3. Atoms –vs.- Molecules • Some elements exist as single atoms. • Smallest partricle of an element that retains the properties of the element. • Other elements exist as molecules. • Molecules consist of 2 or more atoms combined in a definite ratio.

  4. Compounds • A substance made up of atoms of two or more different elements joined by chemical bonds.

  5. What is the difference between a compound and a molecule? • A molecule is formed when two or more atoms join together chemically. • A compoundis a molecule that contains at least two different elements. • All compounds are molecules but not all molecules are compounds.

  6. Mixture: A sample of matter that contains two or more pure substances (elements and compounds) and has variable composition. • The substances retain their chemical properties. • They are not chemically bonded.

  7. Exhaust –a Mixture

  8. Mixtures and compounds differ in two ways… • Substances in a mixture keep their individual properties. • Parts of a mixture are not necessarily present in specific ratios.

  9. Solutions • Homogeneous mixture: is a substance in which two or more substances are uniformly spread out. • Example: salt water, stainless steel, maple syrup • Solution is another term for homogeneous mixture. • Heterogeneous Mixture: A mixture contains substances that are not evenly mixed. • Example: Orange juice, granite, sand

  10. The Properties of a compound differ from the properties of the elements that make them up.

  11. Salt= NaCl • Properties of Sodium: • Shiny, silvery-white, soft, solid element. • Metallic Element • Melting Point of 98 oC • Boiling Point of 883 oC • Most reactive of all the common elements. • Has to be stored under oil. • Never found as a free element in the environment. • Always found combined with other elements • Properties of Chlorine: • Pale green, poisonous gas with a choking odor. • Kills living cells. • Slightly soluble • Gas until -34 oC then turns into a liquid • Very Reactive • Properties of Salt: • White solid at room temperature. • The crystals are brittle. • Melting Point 800 oC • Conducts electricity when melted or in aqueous solutions. • Soluble in water. • Unreactive • Safe to store for long periods of time. • Used to season food. Safe to eat.

  12. Carbon Dioxide = CO2 • Properties of Carbon: • Nonmetal • Fairly unreactive at room temperature. • Reacts with many elements at higher temperatures. • Majority of compounds in living organisms have carbon in them. • Solid at room temperature. • Melting Point 3,527oC • Boiling Point 4,027oC • Properties of Oxygen: • Nonmetal • Colorless, odorless, and tasteless gas • Oxygen reacts during combustion reactions. • Turns into a liquid when cooled to -183 oC. • Properties of Carbon Dioxide: • Colorless, odorless, and tasteless gas. • Changes directly to a solid at -80 oC • Soluble in water • Relatively stable • Extinguishes Fire • Burning carbon compounds in air will make carbon dioxide.

  13. Water = H2O • Properties of Hydrogen: • Lightest most abundant element in the universe. • Nonmetal • Odorless, tasteless, and colorless gas • Very Reactive • Seldom found as a free element • Must be cooled to -253 oC to turn to a liquid. • Does not conduct electricity • Slightly soluble. • Properties of Oxygen: • Nonmetal • Colorless, odorless, and tasteless gas • Oxygen reacts during combustion reactions. • Turns into a liquid when cooled to -183 oC. • Properties of Water: • Occurs on earth in all 3 states of matter • Does not conduct electricity in any of the states • Universal Solvent • Stable Compound • Acts as a medium for chemical reactions

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