Transcript Slide 1
Elements Combine to Form Compounds Name the Super – Heroes Compound – “Pun” Compound - “Pun” Compounds ( 2nd type of Pure Substance) Compound: a pure substance made up of more than one kind of element in which the atoms of the elements are joined together. Compounds form through chemical bonds: these are links between two or more atoms that hold the atoms together Two types of Compounds (chemical bonds) Ionic Compounds Molecular (covalent) Compounds Compounds… Compounds are represented by a combination of element symbols known as a chemical formula: Chemical Formula (tells us): type of elements (atoms) proportion (number) of each atom involved CH4 Elements Present Carbon and Hydrogen NaCl Sodium and Chlorine Proportion: (# of each element) 1 carbon atom and 4 hydrogen atoms 1 sodium atom and 1 chlorine atom Two types of compounds Molecular (covalent) compounds: formed between non- metals only this type of bonding involves sharing of electrons Examples: (we need to know) 1) Carbon Dioxide (gas) - CO2 2) Water - H2O 3) Sucrose (table sugar) – C12H22O11 4) Methane (gas) – CH4 Ionic Compounds formed between metals and non-metals. this type of bonding involves atoms attracting to each other because of opposite charges (+) (-) the atoms involved either gain or loose electrons to form charged particles called Ions (positive or negative) Examples: (we need to know) 1) Sodium Chloride (salt) - NaCl 2) Calcium Carbonate (chalk) - CaCO3 3) Sodium Sulfate (salt) - Na2SO4 4) Sodium Hydroxide (drain cleaner) – NaOH Molecular (Covalent) “share” Ionic “give away and “charge” Ionic Compounds - “Ions” Counting Atoms Chemical Formula Elements Involved Number of Atoms CO2 Carbon (C) Oxygen (O) 3 atoms - 1 carbon (C) - 2 oxygen (O) MgCl Magnesium (Mg) Chlorine (Cl) 2 atoms Na2SO4 Sodium (Na) Sulphur (S) Oxygen (O) 7 atoms - 2 Sodium (Na) - 1 Sulphur (S) - 4 Oxygen (O) C12H22O11 Carbon (C) Hydrogen (H) Oxygen (O) ??? atoms – ___ carbon (C) ___ hydrogen (H) ___ oxygen (O) - 1 magnesium (Mg) - 1 chlorine (Cl) Chemical Formulas Chemical Names of Compounds When given a chemical formula, you can write the chemical name which indicates the elements present in the compound IUPAC (International Union of Pure and Applied Chemistry) a group that represent chemists around the world and is responsible for the rules when naming compounds. Ionic and Molecular compounds have their own set of rules to follow. Naming Compounds Set of rules that you have to follow when writing the names for Ionic and Molecular Compounds. Basic steps: determine the elements involved in the chemical formula (compound)…. Metals and Non- Metals determine the type of compound (Ionic or Molecular) follow the rules outline for Ionic or Molecular Naming Ionic Compounds formed between metals and non-metals. Rules: 1) Name the first element (atom) 2) Name second element by ending the name with the suffix “ide” 3) Put the two names together Example of a Ionic Compound Example : name for the compound NaCl Na (sodium) - metal Cl (chlorine) - non- metal Name: Sodium chloride Naming Molecular (covalent) Compounds formed between non-metals. numbers (subscripts) are important and have to be used at the beginning of each element in the naming of the compound. ……(see page 83) Rules: 1) Name the first element (atom) 2) Name second element by ending the name with the suffix “ide” 3) Add the “prefix” to the element names to show the number of atoms in the compound Example of a Molecular (covalent) Compound Example : name for the compound CO2 C (carbon) - non-metal O (oxygen) – non- metal CO2 [Have to use Prefix to show number of atoms in compound] Name : Carbon dioxide Prefixes (table 3.4, page 83) Number of atoms Prefix 1 Mono (used only for the second atom) 2 di 3 tri 4 tetra 5 penta 6 hexa 7 hepta 8 octa 9 nona 10 deca Name the following compounds Mg3P2 Mg (metal) Magnesium P (non –metal) ….. Ionic Phosphorus Numbers are NOT important … Name: Magnesium phosphide Name the following Compound N2O3 N (non-metal) O (non-metal) …..Molecular (Covalent) Nitrogen Oxygen Numbers are important Name : N2O3 Dinitrogen trioxide Try These ??? 1) Ag3N - 2) CCl4 - Physical Changes Physical Change a change in matter in which NO new substances are produced the appearance of a substance may be changed but the bonds between the particles (atoms) have not broken atoms either move closer together or farther apart Examples - change of state [freezing, melting …] - dissolving [sugar in water] - cutting paper Chemical Changes Chemical Change a change in matter in which NEW substances are produced with NEW properties. Clues that May Indicate a Chemical Change A new color appears Heat or light is given off during the change Bubbles or gas are formed Solid clumps (precipitate) forms in the liquid The change is difficult to reverse Examples: - Corrosion [metals rusting] - Combustion [burning] - Fruit Ripening Chemical Changes and Chemical Reactions Chemical Changes also referred to a Chemical Reaction In every chemical reaction there is something used up and something produced (made) Reactants Products Magnesium + Hydrochloric Acid → Hydrogen + Magnesium Chloride Sodium + Chlorine ------------------→ Sodium Chloride The END !!!!!